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Okiring J, Gonahasa S, Maiteki-Sebuguzi C, Katureebe A, Bagala I, Mutungi P, Kigozi SP, Namuganga JF, Nankabirwa JI, Kamya MR, Donnelly MJ, Churcher TS, Staedke SG, Sherrard-Smith E. LLIN Evaluation in Uganda Project (LLINEUP): modelling the impact of COVID-19-related disruptions on delivery of long-lasting insecticidal nets on malaria indicators in Uganda. Malar J 2024; 23:180. [PMID: 38844987 PMCID: PMC11157881 DOI: 10.1186/s12936-024-05008-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 06/04/2024] [Indexed: 06/09/2024] Open
Abstract
BACKGROUND Disruptions in malaria control due to COVID-19 mitigation measures were predicted to increase malaria morbidity and mortality in Africa substantially. In Uganda, long-lasting insecticidal nets (LLINs) are distributed nationwide every 3-4 years, but the 2020-2021 campaign was altered because of COVID-19 restrictions so that the timing of delivery of new nets was different from the original plans made by the National Malaria Control Programme. METHODS A transmission dynamics modelling exercise was conducted to explore how the altered delivery of LLINs in 2020-2021 impacted malaria burden in Uganda. Data were available on the planned LLIN distribution schedule for 2020-2021, and the actual delivery. The transmission model was used to simulate 100 health sub-districts, and parameterized to match understanding of local mosquito bionomics, net use estimates, and seasonal patterns based on data collected in 2017-2019 during a cluster-randomized trial (LLINEUP). Two scenarios were compared; simulated LLIN distributions matching the actual delivery schedule, and a comparable scenario simulating LLIN distributions as originally planned. Model parameters were otherwise matched between simulations. RESULTS Approximately 70% of the study population received LLINs later than scheduled in 2020-2021, although some areas received LLINs earlier than planned. The model indicates that malaria incidence in 2020 was substantially higher in areas that received LLINs late. In some areas, early distribution of LLINs appeared less effective than the original distribution schedule, possibly due to attrition of LLINs prior to transmission peaks, and waning LLIN efficacy after distribution. On average, the model simulations predicted broadly similar overall mean malaria incidence in 2021 and 2022. After accounting for differences in cluster population size and LLIN distribution dates, no substantial increase in malaria burden was detected. CONCLUSIONS The model results suggest that the disruptions in the 2020-2021 LLIN distribution campaign in Uganda did not substantially increase malaria burden in the study areas.
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Affiliation(s)
- Jaffer Okiring
- Clinical Epidemiology Unit, Makerere University College of Health Sciences, PO Box 7475, Kampala, Uganda.
- Infectious Diseases Research Collaboration, Kampala, Uganda.
| | | | | | | | - Irene Bagala
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Peter Mutungi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Simon P Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Joaniter I Nankabirwa
- Clinical Epidemiology Unit, Makerere University College of Health Sciences, PO Box 7475, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University, Kampala, Uganda
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Wellcome Sanger Institute, Hinxton, UK
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
| | - Sarah G Staedke
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, UK
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
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De Salazar PM, Kamau A, Cavelan A, Akech S, Mpimbaza A, Snow RW, Penny MA. Severe outcomes of malaria in children under time-varying exposure. Nat Commun 2024; 15:4069. [PMID: 38744878 PMCID: PMC11094066 DOI: 10.1038/s41467-024-48191-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 04/22/2024] [Indexed: 05/16/2024] Open
Abstract
In malaria epidemiology, interpolation frameworks based on available observations are critical for policy decisions and interpreting disease burden. Updating our understanding of the empirical evidence across different populations, settings, and timeframes is crucial to improving inference for supporting public health. Here, via individual-based modeling, we evaluate a large, multicountry, contemporary Plasmodium falciparum severe malaria dataset to better understand the relationship between prevalence and incidence of malaria pediatric hospitalizations - a proxy of malaria severe outcomes- in East-Africa. We find that life-long exposure dynamics, and subsequent protection patterns in children, substantially determine the likelihood of malaria hospitalizations relative to ongoing prevalence at the population level. Unsteady transmission patterns over a lifetime in children -increasing or decreasing- lead to an exponential relationship of hospitalization rates versus prevalence rather than the asymptotic pattern observed under steady transmission. Addressing this increase in the complexity of malaria epidemiology is crucial to update burden assessments via inference models that guide current and future policy decisions.
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Affiliation(s)
- Pablo M De Salazar
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Allschwil, Switzerland.
- University of Basel, Basel, Switzerland.
| | - Alice Kamau
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Aurelien Cavelan
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Samuel Akech
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Arthur Mpimbaza
- Child Health and Development Centre, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Robert W Snow
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Melissa A Penny
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Allschwil, Switzerland.
- University of Basel, Basel, Switzerland.
- Telethon Kids Institute, Nedlands, WA, Australia.
- Centre for Child Health Research, University of Western Australia, Crawley, WA, Australia.
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Balam S, Miura K, Ayadi I, Konaté D, Incandela NC, Agnolon V, Guindo MA, Diakité SA, Olugbile S, Nebie I, Herrera SM, Long C, Kajava AV, Diakité M, Corradin G, Herrera S, Herrera MA. Cross-reactivity of r Pvs48/45, a recombinant Plasmodium vivax protein, with sera from Plasmodium falciparum endemic areas of Africa. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.10.588966. [PMID: 38659832 PMCID: PMC11042229 DOI: 10.1101/2024.04.10.588966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Background Ps48/45, a Plasmodium gametocyte surface protein, is a promising candidate for malaria transmission-blocking (TB) vaccine. Due to its relevance for a multispecies vaccine, we explored the cross-reactivity and TB activity of a recombinant P. vivax Ps48/45 protein (rPvs48/45) with sera from P. falciparum-exposed African donors. Methods rPvs48/45 was produced in Chinese hamster ovary cell lines and tested by ELISA for its cross-reactivity with sera from Burkina Faso, Tanzania, Mali, and Nigeria - In addition, BALB/c mice were immunized with the rPvs48/45 protein formulated in Montanide ISA-51 and inoculated with a crude extract of P. falciparum NF-54 gametocytes to evaluate the parasite-boosting effect on rPvs48/45 antibody titers. Specific anti-rPvs48/45 IgG purified from African sera was used to evaluate the ex vivo TB activity on P. falciparum, using standard mosquito membrane feeding assays (SMFA). Results rPvs48/45 protein showed cross-reactivity with sera of individuals from all four African countries, in proportions ranging from 94% (Tanzania) to 40% (Nigeria). Also, the level of cross-reactive antibodies varied significantly between countries (p<0.0001), with a higher antibody level in Mali and the lowest in Nigeria. In addition, antibody levels were higher in adults (≥ 17 years) than young children (≤ 5 years) in both Mali and Tanzania, with a higher proportion of responders in adults (90%) than in children (61%) (p<0.0001) in Mali, where male (75%) and female (80%) displayed similar antibody responses. Furthermore, immunization of mice with P. falciparum gametocytes boosted anti-Pvs48/45 antibody responses, recognizing P. falciparum gametocytes in indirect immunofluorescence antibody test. Notably, rPvs48/45 affinity-purified African IgG exhibited a TB activity of 61% against P. falciparum in SMFA. Conclusion African sera (exposed only to P. falciparum) cross-recognized the rPvs48/45 protein. This, together with the functional activity of IgG, warrants further studies for the potential development of a P. vivax and P. falciparum cross-protective TB vaccine.
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Affiliation(s)
- Saidou Balam
- International Center for Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako (USTTB), Bamako, Mali
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Imen Ayadi
- Immunobiology Department, University of Lausanne, Lausanne, Switzerland
| | - Drissa Konaté
- International Center for Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako (USTTB), Bamako, Mali
| | | | - Valentina Agnolon
- Division of Immunology and Allergy, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland aaaa
| | - Merepen A Guindo
- International Center for Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako (USTTB), Bamako, Mali
| | - Seidina A.S. Diakité
- International Center for Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako (USTTB), Bamako, Mali
| | - Sope Olugbile
- Immunobiology Department, University of Lausanne, Lausanne, Switzerland
| | - Issa Nebie
- Groupe de Recherche Action Santé (GRAS), Burkina Faso, West Africa
| | | | - Carole Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
| | - Andrey V. Kajava
- Montpellier Cell Biology Research Center (CRBM), University of Montpellier, CNRS, France
| | - Mahamadou Diakité
- International Center for Excellence in Research (ICER-Mali), University of Sciences, Techniques and Technologies of Bamako (USTTB), Bamako, Mali
| | | | - Socrates Herrera
- Caucaseco Scientific Research Center, Cali, Colombia
- Malaria Vaccine and Drug Development Center, Cali, Colombia
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Walker IS, Rogerson SJ. Pathogenicity and virulence of malaria: Sticky problems and tricky solutions. Virulence 2023; 14:2150456. [PMID: 36419237 PMCID: PMC9815252 DOI: 10.1080/21505594.2022.2150456] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 11/25/2022] Open
Abstract
Infections with Plasmodium falciparum and Plasmodium vivax cause over 600,000 deaths each year, concentrated in Africa and in young children, but much of the world's population remain at risk of infection. In this article, we review the latest developments in the immunogenicity and pathogenesis of malaria, with a particular focus on P. falciparum, the leading malaria killer. Pathogenic factors include parasite-derived toxins and variant surface antigens on infected erythrocytes that mediate sequestration in the deep vasculature. Host response to parasite toxins and to variant antigens is an important determinant of disease severity. Understanding how parasites sequester, and how antibody to variant antigens could prevent sequestration, may lead to new approaches to treat and prevent disease. Difficulties in malaria diagnosis, drug resistance, and specific challenges of treating P. vivax pose challenges to malaria elimination, but vaccines and other preventive strategies may offer improved disease control.
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Affiliation(s)
- Isobel S Walker
- Department of Infectious Diseases, The University of Melbourne, The Doherty Institute, Melbourne, Australia
| | - Stephen J Rogerson
- Department of Infectious Diseases, The University of Melbourne, The Doherty Institute, Melbourne, Australia
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de Assis GMP, de Alvarenga DAM, Souza LBE, Sánchez-Arcila JC, Silva EFE, de Pina-Costa A, Gonçalves GHP, Souza JCDJ, Nunes AJD, Pissinatti A, Moreira SB, Torres LDM, Costa HL, Tinoco HDP, Pereira VDS, Soares IDS, de Sousa TN, Ntumngia FB, Adams JH, Kano FS, Hirano ZMB, Pratt-Riccio LR, Daniel-Ribeiro CT, Ferreira JO, Carvalho LH, Alves de Brito CF. IgM antibody responses against Plasmodium antigens in neotropical primates in the Brazilian Atlantic Forest. Front Cell Infect Microbiol 2023; 13:1169552. [PMID: 37829607 PMCID: PMC10565664 DOI: 10.3389/fcimb.2023.1169552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 08/11/2023] [Indexed: 10/14/2023] Open
Abstract
Introduction Zoonotic transmission is a challenge for the control and elimination of malaria. It has been recorded in the Atlantic Forest, outside the Amazon which is the endemic region in Brazil. However, only very few studies have assessed the antibody response, especially of IgM antibodies, in Neotropical primates (NP). Therefore, in order to contribute to a better understanding of the immune response in different hosts and facilitate the identification of potential reservoirs, in this study, naturally acquired IgM antibody responses against Plasmodium antigens were evaluated, for the first time, in NP from the Atlantic Forest. Methods The study was carried out using 154 NP samples from three different areas of the Atlantic Forest. IgM antibodies against peptides of the circumsporozoite protein (CSP) from different Plasmodium species and different erythrocytic stage antigens were detected by ELISA. Results Fifty-nine percent of NP had IgM antibodies against at least one CSP peptide and 87% against at least one Plasmodium vivax erythrocytic stage antigen. Levels of antibodies against PvAMA-1 were the highest compared to the other antigens. All families of NP showed IgM antibodies against CSP peptides, and, most strikingly, against erythrocytic stage antigens. Generalized linear models demonstrated that IgM positivity against PvCSP and PvAMA-1 was associated with PCR-detectable blood-stage malaria infection and the host being free-living. Interestingly, animals with IgM against both PvCSP and PvAMA-1 were 4.7 times more likely to be PCR positive than animals that did not have IgM for these two antigens simultaneously. Discussion IgM antibodies against different Plasmodium spp. antigens are present in NP from the Atlantic Forest. High seroprevalence and antibody levels against blood-stage antigens were observed, which had a significant association with molecular evidence of infection. IgM antibodies against CSP and AMA-1 may be used as a potential marker for the identification of NP infected with Plasmodium, which are reservoirs of malaria in the Brazilian Atlantic Forest.
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Affiliation(s)
- Gabriela Maíra Pereira de Assis
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | | | - Luisa Braga e Souza
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | - Juan Camilo Sánchez-Arcila
- School of Natural Sciences, Molecular and Cell Biology Department, University of California, Merced, Merced, CA, United States
| | | | - Anielle de Pina-Costa
- Laboratório de Doenças Febris Agudas, Instituto Nacional de Infectologia Evandro Chagas (INI), Fiocruz, Rio de Janeiro, Brazil
- Centro de Pesquisa, Diagnóstico e Treinamento em Malária (CPD-Mal), Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil
- Escola de Enfermagem Aurora de Afonso Costa, Departamento de Doenças infecciosas e Parasitárias, Universidade Federal Fluminense, Niterói, Brazil
| | | | | | - Ana Julia Dutra Nunes
- Fundação Universidade Regional de Blumenau (FURB), Blumenau, Brazil
- Centro de Pesquisas Biológicas de Indaial, Indaial, Brazil
- Programa de conservação do Bugio Ruivo, Perini Business Park, Joinville, Brazil
| | - Alcides Pissinatti
- Centro de Primatologia do Rio de Janeiro (CPRJ), Instituto Estadual do Ambiente (INEA), Guapimirim, Brazil
- Centro Universitário Serra dos Órgãos (Unifeso), Teresópolis, Brazil
| | - Silvia Bahadian Moreira
- Centro de Primatologia do Rio de Janeiro (CPRJ), Instituto Estadual do Ambiente (INEA), Guapimirim, Brazil
| | - Leticia de Menezes Torres
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | - Helena Lott Costa
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | | | | | - Irene da Silva Soares
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil
| | - Taís Nóbrega de Sousa
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | - Francis Babila Ntumngia
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, FL, United States
| | - John H. Adams
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, FL, United States
| | - Flora Satiko Kano
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | - Zelinda Maria Braga Hirano
- Fundação Universidade Regional de Blumenau (FURB), Blumenau, Brazil
- Centro de Pesquisas Biológicas de Indaial, Indaial, Brazil
- Programa de conservação do Bugio Ruivo, Perini Business Park, Joinville, Brazil
| | - Lilian Rose Pratt-Riccio
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil
| | - Cláudio Tadeu Daniel-Ribeiro
- Centro de Pesquisa, Diagnóstico e Treinamento em Malária (CPD-Mal), Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
- Laboratório de Pesquisa em Malária, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil
| | - Joseli Oliveira Ferreira
- Laboratório de Imunoparasitologia, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil
| | - Luzia Helena Carvalho
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
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6
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Biabi MFAB, Fogang B, Essangui E, Maloba F, Donkeu C, Keumoe R, Cheteug G, Magoudjou N, Slam C, Kemleu S, Efange N, Perraut R, Nsango SE, Eboumbou Moukoko CE, Assam JPA, Etoa FX, Lamb T, Ayong L. High Prevalence of Polyclonal Plasmodium falciparum Infections and Association with Poor IgG Antibody Responses in a Hyper-Endemic Area in Cameroon. Trop Med Infect Dis 2023; 8:390. [PMID: 37624328 PMCID: PMC10459087 DOI: 10.3390/tropicalmed8080390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 08/26/2023] Open
Abstract
Malaria remains a major public health problem worldwide, with eradication efforts thwarted by drug and insecticide resistance and the lack of a broadly effective malaria vaccine. In continuously exposed communities, polyclonal infections are thought to reduce the risk of severe disease and promote the establishment of asymptomatic infections. We sought to investigate the relationship between the complexity of P. falciparum infection and underlying host adaptive immune responses in an area with a high prevalence of asymptomatic parasitaemia in Cameroon. A cross-sectional study of 353 individuals aged 2 to 86 years (median age = 16 years) was conducted in five villages in the Centre Region of Cameroon. Plasmodium falciparum infection was detected by multiplex nested PCR in 316 samples, of which 278 were successfully genotyped. Of these, 60.1% (167/278) were polyclonal infections, the majority (80.2%) of which were from asymptomatic carriers. Host-parasite factors associated with polyclonal infection in the study population included peripheral blood parasite density, participant age and village of residence. The number of parasite clones per infected sample increased significantly with parasite density (r = 0.3912, p < 0.0001) but decreased with participant age (r = -0.4860, p < 0.0001). Parasitaemia and the number of clones per sample correlated negatively with total plasma levels of IgG antibodies to three highly reactive P. falciparum antigens (MSP-1p19, MSP-3 and EBA175) and two soluble antigen extracts (merozoite and mixed stage antigens). Surprisingly, we observed no association between the frequency of polyclonal infection and susceptibility to clinical disease as assessed by the recent occurrence of malarial symptoms or duration since the previous fever episode. Overall, the data indicate that in areas with the high perennial transmission of P. falciparum, parasite polyclonality is dependent on underlying host antibody responses, with the majority of polyclonal infections occurring in persons with low levels of protective anti-plasmodial antibodies.
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Affiliation(s)
- Marie Florence A Bite Biabi
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biochemistry, Faculty of Science, University of Douala, Douala BP 2701, Cameroon
| | - Balotin Fogang
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon
| | - Estelle Essangui
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala BP 2701, Cameroon
| | - Franklin Maloba
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
| | - Christiane Donkeu
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon
| | - Rodrigue Keumoe
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biochemistry, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon
| | - Glwadys Cheteug
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Medical Laboratory Sciences, Faculty of Science, University of Buea, Buea BP 63, Cameroon
| | - Nina Magoudjou
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biochemistry, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon
| | - Celine Slam
- Department of Pathology, School of Medicine, University of Utah, 15 N Medical Drive, Salt Lake City, UT 84112, USA;
| | - Sylvie Kemleu
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
| | - Noella Efange
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biochemistry, Faculty of Science, University of Buea, Buea BP 63, Cameroon
| | - Ronald Perraut
- Centre Pasteur du Cameroun Annex, Garoua BP 921, Cameroon;
| | - Sandrine Eveline Nsango
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala BP 2701, Cameroon
| | - Carole Else Eboumbou Moukoko
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala BP 2701, Cameroon
| | - Jean Paul Assam Assam
- Department of Microbiology, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon; (J.P.A.A.); (F.-X.E.)
| | - François-Xavier Etoa
- Department of Microbiology, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon; (J.P.A.A.); (F.-X.E.)
| | - Tracey Lamb
- Department of Pathology, School of Medicine, University of Utah, 15 N Medical Drive, Salt Lake City, UT 84112, USA;
| | - Lawrence Ayong
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
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7
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Burkitt lymphoma risk shows geographic and temporal associations with Plasmodium falciparum infections in Uganda, Tanzania, and Kenya. Proc Natl Acad Sci U S A 2023; 120:e2211055120. [PMID: 36595676 PMCID: PMC9926229 DOI: 10.1073/pnas.2211055120] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Endemic Burkitt lymphoma (eBL) is a pediatric cancer coendemic with malaria in sub-Saharan Africa, suggesting an etiological link between them. However, previous cross-sectional studies of limited geographic areas have not found a convincing association. We used spatially detailed data from the Epidemiology of Burkitt Lymphoma in East African Children and Minors (EMBLEM) study to assess this relationship. EMBLEM is a case-control study of eBL from 2010 through 2016 in six regions of Kenya, Uganda, and Tanzania. To measure the intensity of exposure to the malaria parasite, Plasmodium falciparum, among children in these regions, we used high-resolution spatial data from the Malaria Atlas Project to estimate the annual number of P. falciparum infections from 2000 through 2016 for each of 49 districts within the study region. Cumulative P. falciparum exposure, calculated as the sum of annual infections by birth cohort, varied widely, with a median of 47 estimated infections per child by age 10, ranging from 4 to 315 infections. eBL incidence increased 39% for each 100 additional lifetime P. falciparum infections (95% CI: 6.10 to 81.04%) with the risk peaking among children aged 5 to 11 and declining thereafter. Alternative models using estimated annual P. falciparum infections 0 to 10 y before eBL onset were inconclusive, suggesting that eBL risk is a function of cumulative rather than recent cross-sectional exposure. Our findings provide population-level evidence that eBL is a phenotype related to heavy lifetime exposure to P. falciparum malaria and support emphasizing the link between malaria and eBL.
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8
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Rahim MAFA, Munajat MB, Dian ND, Seri Rakna MIM, Wahid W, Ghazali N, Hassan NW, Abdul Manap SNA, Kasri MRM, Mohamed AI, Osman E, Chuangchaiya S, Lubis IND, Divis PCS, Kaneko A, Tetteh KKA, Idris ZM. Naturally acquired antibody response to Plasmodium falciparum and Plasmodium vivax among indigenous Orang Asli communities in Peninsular Malaysia. Front Cell Infect Microbiol 2023; 13:1165634. [PMID: 37153151 PMCID: PMC10157193 DOI: 10.3389/fcimb.2023.1165634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/03/2023] [Indexed: 05/09/2023] Open
Abstract
Malaria remains a public health problem in many parts of the world. In Malaysia, the significant progress towards the national elimination programme and effective disease notification on malaria has resulted in zero indigenous human malaria cases since 2018. However, the country still needs to determine the extent of malaria exposure and transmission patterns, particularly in high-risk populations. In this study, a serological method was used to measure transmission levels of Plasmodium falciparum and Plasmodium vivax among indigenous Orang Asli communities in Kelantan, Peninsular Malaysia. A community-based cross-sectional survey was conducted in three Orang Asli communities (i.e., Pos Bihai, Pos Gob, and Pos Kuala Betis) in Kelantan from June to July 2019. Antibody responses to malaria were assessed by enzyme-linked immunosorbent assay (ELISA) using two P. falciparum (PfAMA-1 and PfMSP-119) and two P. vivax (PvAMA-1 and PvMSP-119) antigens. Age-adjusted antibody responses were analysed using a reversible catalytic model to calculate seroconversion rates (SCRs). Multiple logistic regression was used to investigate factors associated with malaria exposure. The overall malaria seroprevalence was 38.8% for PfAMA-1, 36.4% for PfMSP-119, 2.2% for PvAMA-1, and 9.3% for PvMSP-119. Between study areas, the proportion of seropositivity for any P. falciparum and P. vivax antigens was significantly highest in Pos Kuala Betis with 34.7% (p < 0.001) and 13.6% (p < 0.001), respectively. For all parasite antigens except for PvAMA-1, the proportion of seropositive individuals significantly increased with age (all p < 0.001). Based on the SCR, there was a higher level of P. falciparum transmission than P. vivax in the study area. Multivariate regression analyses showed that living in Pos Kuala Betis was associated with both P. falciparum (adjusted odds ratio [aOR] 5.6, p < 0.001) and P. vivax (aOR 2.1, p < 0.001) seropositivities. Significant associations were also found between age and seropositivity to P. falciparum and P. vivax antigens. Analysis of community-based serological data helps describe the level of transmission, heterogeneity, and factors associated with malaria exposure among indigenous communities in Peninsular Malaysia. This approach could be an important adjunct tool for malaria monitoring and surveillance in low malaria transmission settings in the country.
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Affiliation(s)
- Mohd Amirul Fitri A. Rahim
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
| | - Mohd Bakhtiar Munajat
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
| | - Nor Diyana Dian
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
| | | | - Wathiqah Wahid
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
| | - Nuraffini Ghazali
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
| | - Noor Wanie Hassan
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
| | - Siti Nor Azreen Abdul Manap
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
| | | | | | - Emelia Osman
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
| | - Sriwipa Chuangchaiya
- Department of Community Health, Faculty of Public Health, Kasetsart University, Sakon Nakhon, Thailand
| | - Inke Nadia D. Lubis
- Department of Paediatric, Faculty of Medicine, Universitas Sumatera Utara, Medan, Indonesia
| | - Paul C. S. Divis
- Malaria Research Centre, Faculty of Medicine and Health Sciences, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia
| | - Akira Kaneko
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
- Department of Parasitology, Graduate School of Medicine, Osaka City University, Osaka, Japan
| | - Kevin K. A. Tetteh
- Department of Infection Biology, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Zulkarnain Md Idris
- Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur, Malaysia
- *Correspondence: Zulkarnain Md Idris,
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9
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The Impact of Submicroscopic Parasitemia on Malaria Rapid Diagnosis in Northeastern Tanzania, an Area with Diverse Transmission Patterns. Infect Dis Rep 2022; 14:798-809. [PMID: 36412740 PMCID: PMC9680434 DOI: 10.3390/idr14060082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 08/07/2022] [Accepted: 08/08/2022] [Indexed: 12/14/2022] Open
Abstract
Global malaria epidemiology has changed in the last decade with a substantial increase in cases and deaths being recorded. Tanzania accounts for about 4% of all cases and deaths reported in recent years. Several factors contribute to the resurgence of malaria, parasite resistance to antimalarials and mosquito resistance to insecticides being at the top of the list. The presence of sub-microscopic infections poses a significant challenge to malaria rapid diagnostic tests (mRDT). Our cross-sectional surveys in Handeni and Moshi, Tanzania assessed the effect of low parasite density on mRDT. Handeni had higher malaria prevalence by mRDT (39.6%), light microscopy (LM) (16.9%) and polymerase chain reaction (PCR) (18.5%), compared to Moshi with prevalence of 0.2%, 1.3% and 2.3%, respectively. A significant difference (p ˂ 0.001) in malaria prevalence by mRDT, LM and nested PCR was found among age groups. In comparison to all other groups, school-age children (5-15 years) had the highest prevalence of malaria. Our results show that mRDT may miss up to 6% of cases of malaria mainly due to low-density parasitemia when compared to LM and PCR. Routinely used mRDT will likely miss the sub-microscopic parasitemia which will ultimately contribute to the spread of malaria and hinder efforts of elimination.
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10
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Inferring the epidemiological benefit of indoor vector control interventions against malaria from mosquito data. Nat Commun 2022; 13:3862. [PMID: 35790746 PMCID: PMC9256631 DOI: 10.1038/s41467-022-30700-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 05/11/2022] [Indexed: 12/03/2022] Open
Abstract
The cause of malaria transmission has been known for over a century but it is still unclear whether entomological measures are sufficiently reliable to inform policy decisions in human health. Decision-making on the effectiveness of new insecticide-treated nets (ITNs) and the indoor residual spraying of insecticide (IRS) have been based on epidemiological data, typically collected in cluster-randomised control trials. The number of these trials that can be conducted is limited. Here we use a systematic review to highlight that efficacy estimates of the same intervention may vary substantially between trials. Analyses indicate that mosquito data collected in experimental hut trials can be used to parameterize mechanistic models for Plasmodium falciparum malaria and reliably predict the epidemiological efficacy of quick-acting, neuro-acting ITNs and IRS. Results suggest that for certain types of ITNs and IRS using this framework instead of clinical endpoints could support policy and expedite the widespread use of novel technologies. Estimating the effectiveness of malaria vector control interventions has typically relied on resource-intensive cluster randomised trials. Here, the authors estimate changes in malaria prevalence using entomological data from experimental hut trials, which may provide an alternative route to approval of interventions in some situations.
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11
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Arias CF, Acosta FJ, Fernandez-Arias C. Killing the competition: a theoretical framework for liver-stage malaria. Open Biol 2022; 12:210341. [PMID: 35350863 PMCID: PMC8965401 DOI: 10.1098/rsob.210341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The first stage of malaria infections takes place inside the host's hepatocytes. Remarkably, Plasmodium parasites do not infect hepatocytes immediately after reaching the liver. Instead, they migrate through several hepatocytes before infecting their definitive host cells, thus increasing their chances of immune destruction. Considering that malaria can proceed normally without cell traversal, this is indeed a puzzling behaviour. In fact, the role of hepatocyte traversal remains unknown to date, implying that the current understanding of malaria is incomplete. In this work, we hypothesize that the parasites traverse hepatocytes to actively trigger an immune response in the host. This behaviour would be part of a strategy of superinfection exclusion aimed to reduce intraspecific competition during the blood stage of the infection. Based on this hypothesis, we formulate a comprehensive theory of liver-stage malaria that integrates all the available knowledge about the infection. The interest of this new paradigm is not merely theoretical. It highlights major issues in the current empirical approach to the study of Plasmodium and suggests new strategies to fight malaria.
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Affiliation(s)
- Clemente F. Arias
- Centro de Investigaciones Biológicas (CSIC), Madrid, Spain,Grupo Interdisciplinar de Sistemas Complejos de Madrid, Spain
| | | | - Cristina Fernandez-Arias
- Departamento de Inmunología, Universidad Complutense de Madrid, Spain,Instituto de Medicina Molecular, Universidade de Lisboa, Portugal
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12
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O'Flaherty K, Roe M, Fowkes FJ. The role of naturally acquired antimalarial antibodies in subclinical
Plasmodium
spp. infection. J Leukoc Biol 2022; 111:1097-1105. [PMID: 35060185 PMCID: PMC9303632 DOI: 10.1002/jlb.5mr1021-537r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/09/2021] [Indexed: 12/17/2022] Open
Affiliation(s)
- Katherine O'Flaherty
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
| | - Merryn Roe
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
- School of Public Health and Preventive Medicine Monash University Melbourne Australia
| | - Freya J.I. Fowkes
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
- School of Public Health and Preventive Medicine Monash University Melbourne Australia
- Centre for Epidemiology and Biostatistics Melbourne School of Population and Global Health, The University of Melbourne Melbourne Australia
- Department of Infectious Disease Monash University Melbourne Australia
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13
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Coleman S, Yihdego Y, Sherrard-Smith E, Thomas CS, Dengela D, Oxborough RM, Dadzie SK, Boakye D, Gyamfi F, Obiri-Danso K, Johns B, Siems LV, Lucas B, Tongren JE, Zigirumugabe S, Dery D, Fornadel C, George K, Belemvire A, Carlson J, Irish SR, Armistead JS, Seyoum A. Partial indoor residual spraying with pirimiphos-methyl as an effective and cost-saving measure for the control of Anopheles gambiae s.l. in northern Ghana. Sci Rep 2021; 11:18055. [PMID: 34508114 PMCID: PMC8433436 DOI: 10.1038/s41598-021-97138-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 08/19/2021] [Indexed: 11/09/2022] Open
Abstract
The scale up of indoor residual spraying (IRS) and insecticide treated nets have contributed significantly to global reductions in malaria prevalence over the last two decades. However, widespread pyrethroid resistance has necessitated the use of new and more expensive insecticides for IRS. Partial IRS with pirimiphos-methyl in experimental huts and houses in a village-wide trial was evaluated against Anopheles gambiae s.l. in northern Ghana. Four different scenarios in which either only the top or bottom half of the walls of experimental huts were sprayed, with or without also spraying the ceiling were compared. Mortality of An. gambiae s.l. on partially sprayed walls was compared with the standard procedures in which all walls and ceiling surfaces are sprayed. A small-scale trial was then conducted to assess the effectiveness, feasibility, and cost of spraying only the upper walls and ceiling as compared to full IRS and no spraying in northern Ghana. Human landing catches were conducted to estimate entomological indices and determine the effectiveness of partial IRS. An established transmission dynamics model was parameterized by an analysis of the experimental hut data and used to predict the epidemiological impact and cost effectiveness of partial IRS for malaria control in northern Ghana. In the experimental huts, partial IRS of the top (IRR 0.89, p = 0.13) or bottom (IRR 0.90, p = 0.15) half of walls and the ceiling was not significantly less effective than full IRS in terms of mosquito mortality. In the village trial, the annual entomological inoculation rate was higher for the unsprayed control (217 infective bites/person/year (ib/p/yr)) compared with the fully and partially sprayed sites, with 28 and 38 ib/p/yr, respectively. The transmission model predicts that the efficacy of partial IRS against all-age prevalence of malaria after six months would be broadly equivalent to a full IRS campaign in which 40% reduction is expected relative to no spray campaign. At scale, partial IRS in northern Ghana would have resulted in a 33% cost savings ($496,426) that would enable spraying of 36,000 additional rooms. These findings suggest that partial IRS is an effective, feasible, and cost saving approach to IRS that could be adopted to sustain and expand implementation of this key malaria control intervention.
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Affiliation(s)
- Sylvester Coleman
- PMI VectorLink Project, Abt Associates, Plot 11 Waterson Road, Fuo, Tamale, Ghana.
| | - Yemane Yihdego
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Ellie Sherrard-Smith
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
| | - Churcher S Thomas
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
| | - Dereje Dengela
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Richard M Oxborough
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Samuel K Dadzie
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Daniel Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Frank Gyamfi
- PMI VectorLink Project, Abt Associates, Plot 11 Waterson Road, Fuo, Tamale, Ghana
| | - Kwasi Obiri-Danso
- Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Ben Johns
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Lilly V Siems
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Bradford Lucas
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Jon Eric Tongren
- US. President's Malaria Initiative, U.S. Agency for International Development, Accra, Ghana
| | - Sixte Zigirumugabe
- US. President's Malaria Initiative, U.S. Agency for International Development, Accra, Ghana
| | - Dominic Dery
- US. President's Malaria Initiative, U.S. Agency for International Development, Accra, Ghana
| | - Christen Fornadel
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Kristen George
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Allison Belemvire
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Jenny Carlson
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Seth R Irish
- U.S. President's Malaria Initiative, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jennifer S Armistead
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Aklilu Seyoum
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
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14
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Paton RS, Kamau A, Akech S, Agweyu A, Ogero M, Mwandawiro C, Mturi N, Mohammed S, Mpimbaza A, Kariuki S, Otieno NA, Nyawanda BO, Mohamed AF, Mtove G, Reyburn H, Gupta S, Bejon P, Lourenço J, Snow RW. Malaria infection and severe disease risks in Africa. Science 2021; 373:926-931. [PMID: 34413238 PMCID: PMC7611598 DOI: 10.1126/science.abj0089] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/29/2021] [Indexed: 12/18/2022]
Abstract
The relationship between community prevalence of Plasmodium falciparum and the burden of severe, life-threatening disease remains poorly defined. To examine the three most common severe malaria phenotypes from catchment populations across East Africa, we assembled a dataset of 6506 hospital admissions for malaria in children aged 3 months to 9 years from 2006 to 2020. Admissions were paired with data from community parasite infection surveys. A Bayesian procedure was used to calibrate uncertainties in exposure (parasite prevalence) and outcomes (severe malaria phenotypes). Each 25% increase in prevalence conferred a doubling of severe malaria admission rates. Severe malaria remains a burden predominantly among young children (3 to 59 months) across a wide range of community prevalence typical of East Africa. This study offers a quantitative framework for linking malaria parasite prevalence and severe disease outcomes in children.
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Affiliation(s)
- Robert S Paton
- Department of Zoology, University of Oxford, Oxford, UK.
| | - Alice Kamau
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Samuel Akech
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Ambrose Agweyu
- Kilimanjaro Christian Medical Centre/Joint Malaria Programme, Moshi, Tanzania
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Morris Ogero
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Charles Mwandawiro
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
| | - Neema Mturi
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Shebe Mohammed
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Arthur Mpimbaza
- Child Health and Development Centre, Makerere University, College of Health Sciences, Kampala, Uganda
| | - Simon Kariuki
- Kenya Medical Research Institute (KEMRI)-Centre for Global Health Research, Kisumu, Kenya
| | - Nancy A Otieno
- Kenya Medical Research Institute (KEMRI)-Centre for Global Health Research, Kisumu, Kenya
| | - Bryan O Nyawanda
- Kenya Medical Research Institute (KEMRI)-Centre for Global Health Research, Kisumu, Kenya
| | - Amina F Mohamed
- Kilimanjaro Christian Medical Centre/Joint Malaria Programme, Moshi, Tanzania
- London School of Hygiene and Tropical Medicine, London, UK
| | - George Mtove
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
| | - Hugh Reyburn
- London School of Hygiene and Tropical Medicine, London, UK
| | - Sunetra Gupta
- Department of Zoology, University of Oxford, Oxford, UK
| | - Philip Bejon
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Kilifi, Kenya
| | - José Lourenço
- Department of Zoology, University of Oxford, Oxford, UK
| | - Robert W Snow
- Kenya Medical Research Institute (KEMRI)-Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
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15
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de Assis GMP, de Alvarenga DAM, Costa Pereira MDO, Sánchez-Arcila JC, de Pina Costa A, de Souza Junior JC, Nunes AJD, Pissinatti A, Moreira SB, de Menezes Torres L, Costa HL, da Penha Tinoco H, Pereira VDS, Soares IDS, de Sousa TN, Ntumngia FB, Adams JH, Kano FS, Hirano ZMB, Daniel-Ribeiro CT, Oliveira Ferreira J, Carvalho LH, Alves de Brito CF. Profiling Humoral Immune Response Against Pre-Erythrocytic and Erythrocytic Antigens of Malaria Parasites Among Neotropical Primates in the Brazilian Atlantic Forest. Front Cell Infect Microbiol 2021; 11:678996. [PMID: 34055672 PMCID: PMC8155606 DOI: 10.3389/fcimb.2021.678996] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/22/2021] [Indexed: 12/22/2022] Open
Abstract
Human malaria due to zoonotic transmission has been recorded in the Atlantic Forest, an extra-Amazonian area in Brazil, which are a challenge for malaria control. Naturally acquired humoral immune response against pre-erythrocytic and erythrocytic antigens of Neotropical primates (NP) was evaluated here to improve the knowledge about the exposure of those animals to the malaria transmission and support the identification of the potential reservoirs of the disease in the Atlantic Forest. Blood samples of 154 monkeys from three areas of the Atlantic Forest were used to identify IgG antibodies against peptides of the repeat region of the major pre-erythrocytic antigen, the circumsporozoite protein (CSP), of Plasmodium vivax (PvCSP), Plasmodium brasilianum/Plasmodium malariae (Pb/PmCSP), and Plasmodium falciparum (PfCSP) by ELISA. Antibodies against erythrocytic recombinant antigens of P. vivax, Apical membrane antigen 1 (PvAMA-1), Erythrocyte binding protein 2 (PvEBP-2) and domain II of Duffy binding protein (PvDBPII) were also evaluated. Parameters, such as age, sex, PCR positivity, and captivity, potentially associated with humoral immune response were analyzed. Eighty-five percent of NP had antibodies against at least one CSP peptide, and 76% against at least one P. vivax erythrocytic antigen. A high percentage of adults compared to non-adults were seropositive and showed increased antibody levels. Neotropical primates with PCR positive for P. simium had a significantly higher frequency of positivity rate for immune response against PvEBP-2, PvDBPII and also higher antibody levels against PvDBPII, compared to PCR negative NPs for this species. Monkeys with PCR positive for P. brasilianum/P. malariae showed higher frequency of seropositivity and antibody levels against Pb/PmCSP. Levels of antibodies against Pb/PmCSP, PvEBP-2 and PvDBPII were higher in free-living than in captive monkeys from the same area. All Platyrrhine families showed antibodies against CSP peptides, however not all showed IgG against erythrocytic antigens. These findings showed a high prevalence of naturally acquired antibodies against CSP repeats in all studied areas, suggesting an intense exposure to infected-mosquitoes bites of NP from all families. However, mainly monkeys of Atelidae family showed antibodies against P. vivax erythrocytic antigens, suggesting blood infection, which might serve as potential reservoirs of malaria in the Atlantic Forest.
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Affiliation(s)
- Gabriela Maíra Pereira de Assis
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | | | | | | | - Anielle de Pina Costa
- Centro de Pesquisa, Diagnóstico e Treinamento em Malária (CPD-Mal), Fiocruz, Rio de Janeiro, Brazil
- Ambulatório de Doenças febris, Instituto Nacional de Infectologia (INI), Ambulatório de Doenças Febris Agudas Fiocruz, Rio de Janeiro, Brazil
- Centro Universitário Serra dos Órgãos (UNIFESO), Teresópolis, Brazil
| | - Júlio César de Souza Junior
- Centro de Pesquisas Biológicas de Indaial, Indaial, Brazil
- Fundação Universidade Regional de Blumenau (FURB), Blumenau, Brazil
| | - Ana Julia Dutra Nunes
- Centro de Pesquisas Biológicas de Indaial, Indaial, Brazil
- Programa de conservação do Bugio Ruivo, Joinville, Brazil
| | - Alcides Pissinatti
- Centro Universitário Serra dos Órgãos (UNIFESO), Teresópolis, Brazil
- Centro de Primatologia do Rio de Janeiro (CPRJ), Instituto Estadual do Ambiente (INEA), Guapimirim, Brazil
| | - Silvia Bahadian Moreira
- Centro de Primatologia do Rio de Janeiro (CPRJ), Instituto Estadual do Ambiente (INEA), Guapimirim, Brazil
| | - Leticia de Menezes Torres
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | - Helena Lott Costa
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | | | | | - Irene da Silva Soares
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil
| | - Taís Nóbrega de Sousa
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | - Francis Babila Ntumngia
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, FL, United States
| | - John H. Adams
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, Tampa, FL, United States
| | - Flora Satiko Kano
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
| | - Zelinda Maria Braga Hirano
- Centro de Pesquisas Biológicas de Indaial, Indaial, Brazil
- Fundação Universidade Regional de Blumenau (FURB), Blumenau, Brazil
| | - Cláudio Tadeu Daniel-Ribeiro
- Centro de Pesquisa, Diagnóstico e Treinamento em Malária (CPD-Mal), Fiocruz, Rio de Janeiro, Brazil
- Laboratório de Pesquisa em Malária, IOC/Fiocruz, Rio de Janeiro, Brazil
| | - Joseli Oliveira Ferreira
- Laboratório de Imunoparasitologia, Instituto Oswaldo Cruz (IOC), Fiocruz, Rio de Janeiro, Brazil
| | - Luzia Helena Carvalho
- Grupo de Pesquisa em Biologia Molecular e Imunologia da malária, Instituto René Rachou/Fiocruz Minas, Belo Horizonte, Brazil
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Boushab BM, Ould Ahmedou Salem MS, Ould Mohamed Salem Boukhary A, Parola P, Basco L. Clinical Features and Mortality Associated with Severe Malaria in Adults in Southern Mauritania. Trop Med Infect Dis 2020; 6:tropicalmed6010001. [PMID: 33375214 PMCID: PMC7838900 DOI: 10.3390/tropicalmed6010001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/15/2020] [Accepted: 12/15/2020] [Indexed: 11/16/2022] Open
Abstract
Severe malaria in adults is not well-studied in Sahelian Africa. Clinical features and mortality associated with severe Plasmodium falciparum malaria in adult patients hospitalized in Kiffa, southern Mauritania, were analysed. Patients over 15 years old admitted for severe malaria between August 2016 and December 2019 were included in the present retrospective study. The World Health Organization (WHO) criteria were used to define severe malaria. The presenting clinical characteristics and outcome were compared. Of 4266 patients hospitalized during the study period, 573 (13.4%) had a positive rapid diagnostic test for malaria, and 99 (17.3%; mean age, 37.5 years; range 15–79 years; sex-ratio M/F, 2.1) satisfied the criteria for severe malaria. On admission, the following signs and symptoms were observed in more than one-fourth of the patients: fever (98%), impairment of consciousness (81.8%), multiple convulsions (70.7%), cardiovascular collapse (61.6%), respiratory distress (43.4%), severe anaemia ≤ 80 g/L (36.4%), haemoglobinuria (27.3%), and renal failure (25.3%). Patients were treated with parenteral quinine or artemether. Fourteen (14.1%) patients died. Multiple convulsions, respiratory distress, severe anaemia, haemoglobinuria, acute renal failure, jaundice, and abnormal bleeding occurred more frequently (p < 0.05) in deceased patients. Mortality due to severe falciparum malaria is high among adults in southern Mauritania. An adoption of the WHO-recommended first-line treatment for severe malaria, such as parenteral artesunate, is required to lower the mortality rate associated with severe malaria.
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Affiliation(s)
- Boushab Mohamed Boushab
- Department of Internal Medicine and Infectious Diseases, Kiffa Regional Hospital, Assaba, Mauritania;
| | - Mohamed Salem Ould Ahmedou Salem
- Unité de Recherche Génomes et Milieux, Faculté des Sciences et Techniques, Université de Nouakchott Al-Aasriya, Nouveau Campus Universitaire, BP 5026, Nouakchott, Mauritania; (M.S.O.A.S.); (A.O.M.S.B.)
| | - Ali Ould Mohamed Salem Boukhary
- Unité de Recherche Génomes et Milieux, Faculté des Sciences et Techniques, Université de Nouakchott Al-Aasriya, Nouveau Campus Universitaire, BP 5026, Nouakchott, Mauritania; (M.S.O.A.S.); (A.O.M.S.B.)
- Institut de Recherche pour le Développement (IRD), Aix-Marseille Université, IRD, AP-HM, SSA, VITROME, 13005 Marseille, France;
- Institut Hospitalo-Universitaire (IHU)-Méditerranée Infection, 13005 Marseille, France
| | - Philippe Parola
- Institut de Recherche pour le Développement (IRD), Aix-Marseille Université, IRD, AP-HM, SSA, VITROME, 13005 Marseille, France;
- Institut Hospitalo-Universitaire (IHU)-Méditerranée Infection, 13005 Marseille, France
| | - Leonardo Basco
- Institut de Recherche pour le Développement (IRD), Aix-Marseille Université, IRD, AP-HM, SSA, VITROME, 13005 Marseille, France;
- Institut Hospitalo-Universitaire (IHU)-Méditerranée Infection, 13005 Marseille, France
- Correspondence:
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17
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The immunoglobulin G antibody response to malaria merozoite antigens in asymptomatic children co-infected with malaria and intestinal parasites. PLoS One 2020; 15:e0242012. [PMID: 33170876 PMCID: PMC7654760 DOI: 10.1371/journal.pone.0242012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 10/24/2020] [Indexed: 02/06/2023] Open
Abstract
Background Co-infection with malaria and intestinal parasites is common in children in Africa and may affect their immune response to a malaria parasite infection. Prior studies suggest that co-infections may lead to increased susceptibility to malaria infection and disease severity; however, other studies have shown the reverse. Knowledge on how co-morbidities specifically affect the immune response to malaria antigens is limited. Therefore, this study sought to determine the prevalence of co-infection of malaria and intestinal parasites and its association with antibody levels to malaria merozoite antigens. Methods A cross sectional study was carried out in two villages with high transmission of malaria in Cameroon (Ngali II and Mfou) where mass drug administration (MDA) had been administered at ~6-month intervals (generally with albendazole or mebendazole). Children aged 1–15 years were enrolled after obtaining parental consent. A malaria rapid diagnostic test was used on site. Four (4) ml of peripheral blood was collected from each participant to determine Plasmodium falciparum infections by microscopy, haemoglobin levels and serology. Fresh stool samples were collected and examined by wet mount, Kato-Katz method and modified Ritchie concentration techniques. A Multiplex Analyte Platform assay was used to measure antibody levels. Results A total of 320 children were enrolled. The prevalence of malaria by blood smear was 76.3% (244/320) and prevalence of malaria and intestinal parasites was 16.9% (54/320). Malaria prevalence was highest in young children; whereas, intestinal parasites (IP+) were not present until after 3 years of age. All children positive for malaria had antibodies to MSP142, MSP2, MSP3 and EBA175. No difference in antibody levels in children with malaria-co infections compared to malaria alone were found, except for antibody levels to EBA-175 were higher in children co-infected with intestinal protozoa (p = 0.018), especially those with Entamoeba histolytica infections (p = 0.0026). Conclusion Antibody levels to EBA175 were significantly higher in children co-infected with malaria and E. histolytica compared to children infected with malaria alone. It is important to further investigate why and how the presence of these protozoans might modulate the immune response to malaria antigens.
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Mousa A, Al-Taiar A, Anstey NM, Badaut C, Barber BE, Bassat Q, Challenger JD, Cunnington AJ, Datta D, Drakeley C, Ghani AC, Gordeuk VR, Grigg MJ, Hugo P, John CC, Mayor A, Migot-Nabias F, Opoka RO, Pasvol G, Rees C, Reyburn H, Riley EM, Shah BN, Sitoe A, Sutherland CJ, Thuma PE, Unger SA, Viwami F, Walther M, Whitty CJM, William T, Okell LC. The impact of delayed treatment of uncomplicated P. falciparum malaria on progression to severe malaria: A systematic review and a pooled multicentre individual-patient meta-analysis. PLoS Med 2020; 17:e1003359. [PMID: 33075101 PMCID: PMC7571702 DOI: 10.1371/journal.pmed.1003359] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 08/26/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Delay in receiving treatment for uncomplicated malaria (UM) is often reported to increase the risk of developing severe malaria (SM), but access to treatment remains low in most high-burden areas. Understanding the contribution of treatment delay on progression to severe disease is critical to determine how quickly patients need to receive treatment and to quantify the impact of widely implemented treatment interventions, such as 'test-and-treat' policies administered by community health workers (CHWs). We conducted a pooled individual-participant meta-analysis to estimate the association between treatment delay and presenting with SM. METHODS AND FINDINGS A search using Ovid MEDLINE and Embase was initially conducted to identify studies on severe Plasmodium falciparum malaria that included information on treatment delay, such as fever duration (inception to 22nd September 2017). Studies identified included 5 case-control and 8 other observational clinical studies of SM and UM cases. Risk of bias was assessed using the Newcastle-Ottawa scale, and all studies were ranked as 'Good', scoring ≥7/10. Individual-patient data (IPD) were pooled from 13 studies of 3,989 (94.1% aged <15 years) SM patients and 5,780 (79.6% aged <15 years) UM cases in Benin, Malaysia, Mozambique, Tanzania, The Gambia, Uganda, Yemen, and Zambia. Definitions of SM were standardised across studies to compare treatment delay in patients with UM and different SM phenotypes using age-adjusted mixed-effects regression. The odds of any SM phenotype were significantly higher in children with longer delays between initial symptoms and arrival at the health facility (odds ratio [OR] = 1.33, 95% CI: 1.07-1.64 for a delay of >24 hours versus ≤24 hours; p = 0.009). Reported illness duration was a strong predictor of presenting with severe malarial anaemia (SMA) in children, with an OR of 2.79 (95% CI:1.92-4.06; p < 0.001) for a delay of 2-3 days and 5.46 (95% CI: 3.49-8.53; p < 0.001) for a delay of >7 days, compared with receiving treatment within 24 hours from symptom onset. We estimate that 42.8% of childhood SMA cases and 48.5% of adult SMA cases in the study areas would have been averted if all individuals were able to access treatment within the first day of symptom onset, if the association is fully causal. In studies specifically recording onset of nonsevere symptoms, long treatment delay was moderately associated with other SM phenotypes (OR [95% CI] >3 to ≤4 days versus ≤24 hours: cerebral malaria [CM] = 2.42 [1.24-4.72], p = 0.01; respiratory distress syndrome [RDS] = 4.09 [1.70-9.82], p = 0.002). In addition to unmeasured confounding, which is commonly present in observational studies, a key limitation is that many severe cases and deaths occur outside healthcare facilities in endemic countries, where the effect of delayed or no treatment is difficult to quantify. CONCLUSIONS Our results quantify the relationship between rapid access to treatment and reduced risk of severe disease, which was particularly strong for SMA. There was some evidence to suggest that progression to other severe phenotypes may also be prevented by prompt treatment, though the association was not as strong, which may be explained by potential selection bias, sample size issues, or a difference in underlying pathology. These findings may help assess the impact of interventions that improve access to treatment.
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Affiliation(s)
- Andria Mousa
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
- * E-mail:
| | - Abdullah Al-Taiar
- School of Community & Environmental Health, College of Health Sciences, Old Dominion University, Norfolk, Virginia, United States of America
| | - Nicholas M. Anstey
- Global Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Division of Medicine, Royal Darwin Hospital, Darwin, Northern Territory, Australia
| | - Cyril Badaut
- Unité de Biothérapie Infectieuse et Immunité, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
- Unité des Virus Emergents (UVE: Aix-Marseille Univ—IRD 190—Inserm 1207—IHU Méditerranée Infection), Marseille, France
| | - Bridget E. Barber
- Global Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Quique Bassat
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- ICREA, Barcelona, Spain
- Pediatric Infectious Diseases Unit, Pediatrics Department, Hospital Sant Joan de Déu (University of Barcelona), Barcelona, Spain
- Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Joseph D. Challenger
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Aubrey J. Cunnington
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, United Kingdom
| | - Dibyadyuti Datta
- Ryan White Center for Pediatric Infectious Disease and Global Health, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Azra C. Ghani
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Victor R. Gordeuk
- Sickle Cell Center, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Matthew J. Grigg
- Global Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Pierre Hugo
- Medicines for Malaria Venture, Geneva, Switzerland
| | - Chandy C. John
- Ryan White Center for Pediatric Infectious Disease and Global Health, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Alfredo Mayor
- ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | | | - Robert O. Opoka
- Department of Paediatrics and Child Health, Makerere University School of Medicine, Kampala, Uganda
| | - Geoffrey Pasvol
- Imperial College London, Department of Life Sciences, London, United Kingdom
| | - Claire Rees
- Centre for Global Public Health, Institute of Population Health Sciences, Barts & The London School of Medicine & Dentistry, London, United Kingdom
| | - Hugh Reyburn
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Eleanor M. Riley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Binal N. Shah
- Sickle Cell Center, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Antonio Sitoe
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Colin J. Sutherland
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | - Stefan A. Unger
- Department of Child Life and Health, University of Edinburgh, United Kingdom
- Department of Respiratory Medicine, Royal Hospital for Sick Children, Edinburgh, United Kingdom
| | - Firmine Viwami
- Institut de Recherche Clinique du Bénin (IRCB), Cotonou, Benin
| | - Michael Walther
- Medical Research Council Unit, Fajara, The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Christopher J. M. Whitty
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Timothy William
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
- Gleneagles Hospital, Kota Kinabalu, Sabah, Malaysia
| | - Lucy C. Okell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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Potential functions of atypical memory B cells in Plasmodium-exposed individuals. Int J Parasitol 2020; 50:1033-1042. [PMID: 32987039 PMCID: PMC7666103 DOI: 10.1016/j.ijpara.2020.08.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 07/28/2020] [Accepted: 08/01/2020] [Indexed: 02/08/2023]
Abstract
Naturally acquired iummunity against clinical malaria is slow to develop, taking years of repeated exposure to parasites to acquire sufficiently broad and potent antibody responses. Increasing evidence suggests that Plasmodium infection and the resulting immune stimulation contribute to changes in the B cell compartment. In particular, accumulation of atypical memory B cells (atMBCs) is common in Plasmodium-exposed individuals. Similarities to B cell subsets present in other acute and chronic disease settings have provided insight into the development and potential function of these cells; however, their contribution to protection against malaria is still poorly understood. Here, we discuss recent findings that have increased our understanding of atMBCs and outline outstanding questions related to their function and development in the protective immune response to malaria.
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20
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Mpimbaza A, Walemwa R, Kapisi J, Sserwanga A, Namuganga JF, Kisambira Y, Tagoola A, Nanteza JF, Rutazaana D, Staedke SG, Dorsey G, Opigo J, Kamau A, Snow RW. The age-specific incidence of hospitalized paediatric malaria in Uganda. BMC Infect Dis 2020; 20:503. [PMID: 32660434 PMCID: PMC7359223 DOI: 10.1186/s12879-020-05215-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/01/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Understanding the relationship between malaria infection risk and disease outcomes represents a fundamental component of morbidity and mortality burden estimations. Contemporary data on severe malaria risks among populations of different parasite exposures are scarce. Using surveillance data, we compared rates of paediatric malaria hospitalisation in areas of varying parasite exposure levels. METHODS Surveillance data at five public hospitals; Jinja, Mubende, Kabale, Tororo, and Apac were assembled among admissions aged 1 month to 14 years between 2017 and 2018. The address of each admission was used to define a local catchment population where national census data was used to define person-year-exposure to risk. Within each catchment, historical infection prevalence was assembled from previously published data and current infection prevalence defined using 33 population-based school surveys among 3400 children. Poisson regression was used to compute the overall and site-specific incidences with 95% confidence intervals. RESULTS Both current and historical Plasmodium falciparum prevalence varied across the five sites. Current prevalence ranged from < 1% in Kabale to 54% in Apac. Overall, the malaria admission incidence rate (IR) was 7.3 per 1000 person years among children aged 1 month to 14 years of age (95% CI: 7.0, 7.7). The lowest rate was described at Kabale (IR = 0.3; 95 CI: 0.1, 0.6) and highest at Apac (IR = 20.3; 95 CI: 18.9, 21.8). There was a correlation between IR across the five sites and the current parasite prevalence in school children, though findings were not statistically significant. Across all sites, except Kabale, malaria admissions were concentrated among young children, 74% were under 5 years. The median age of malaria admissions at Kabale hospital was 40 months (IQR 20, 72), and at Apac hospital was 36 months (IQR 18, 69). Overall, severe anaemia (7.6%) was the most common presentation and unconsciousness (1.8%) the least common. CONCLUSION Malaria hospitalisation rates remain high in Uganda particularly among young children. The incidence of hospitalized malaria in different locations in Uganda appears to be influenced by past parasite exposure, immune acquisition, and current risks of infection. Interruption of transmission through vector control could influence age-specific severe malaria risk.
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Affiliation(s)
- Arthur Mpimbaza
- Child Health and Development Centre, College of Health Sciences, Makerere University, Kampala, Uganda.
- Infectious Diseases Research Collaboration, Kampala, Uganda.
| | - Richard Walemwa
- Department of Prevention, Care and Treatment, Infectious Diseases Institute, Kampala, Uganda
| | - James Kapisi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | | | | | - Abner Tagoola
- Jinja Regional Referral, Hospital, Republic of Uganda Ministry of Health, Jinja, Uganda
| | - Jane Frances Nanteza
- Mubende Regional Referral, Hospital, Republic of Uganda Ministry of Health, Mubende, Uganda
| | - Damain Rutazaana
- National Malaria Control Program, Ministry of Health Uganda, Kampala, Uganda
| | | | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California San Francisco, San Francisco, USA
| | - Jimmy Opigo
- National Malaria Control Program, Ministry of Health Uganda, Kampala, Uganda
| | - Alice Kamau
- Population Health Unit, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
| | - Robert W Snow
- Population Health Unit, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
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Host and Parasite Transcriptomic Changes upon Successive Plasmodium falciparum Infections in Early Childhood. mSystems 2020; 5:5/4/e00116-20. [PMID: 32636334 PMCID: PMC7343306 DOI: 10.1128/msystems.00116-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We show that dual RNA-seq from patient blood samples allows characterization of host/parasite interactions during malaria infections and can provide a solid framework to study the acquisition of antimalarial immunity, as well as the adaptations of P. falciparum to malaria-experienced hosts. Children are highly susceptible to clinical malaria, and in regions where malaria is endemic, their immune systems must face successive encounters with Plasmodium falciparum parasites before they develop immunity, first against severe disease and later against uncomplicated malaria. Understanding cellular and molecular interactions between host and parasites during an infection could provide insights into the processes underlying this gradual acquisition of immunity, as well as to how parasites adapt to infect hosts that are successively more malaria experienced. Here, we describe methods to analyze the host and parasite gene expression profiles generated simultaneously from blood samples collected from five consecutive symptomatic P. falciparum infections in three Malian children. We show that the data generated enable statistical assessment of the proportions of (i) each white blood cell subset and (ii) the parasite developmental stages, as well as investigations of host-parasite gene coexpression. We also use the sequences generated to analyze allelic variations in transcribed regions and determine the complexity of each infection. While limited by the modest sample size, our analyses suggest that host gene expression profiles primarily clustered by individual, while the parasite gene expression profiles seemed to differentiate early from late infections. Overall, this study provides a solid framework to examine the mechanisms underlying acquisition of immunity to malaria infections using whole-blood transcriptome sequencing (RNA-seq). IMPORTANCE We show that dual RNA-seq from patient blood samples allows characterization of host/parasite interactions during malaria infections and can provide a solid framework to study the acquisition of antimalarial immunity, as well as the adaptations of P. falciparum to malaria-experienced hosts.
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22
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Kamau A, Mtanje G, Mataza C, Mwambingu G, Mturi N, Mohammed S, Ong'ayo G, Nyutu G, Nyaguara A, Bejon P, Snow RW. Malaria infection, disease and mortality among children and adults on the coast of Kenya. Malar J 2020; 19:210. [PMID: 32552891 PMCID: PMC7301992 DOI: 10.1186/s12936-020-03286-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Malaria transmission has recently fallen in many parts of Africa, but systematic descriptions of infection and disease across all age groups are rare. Here, an epidemiological investigation of parasite prevalence, the incidence of fevers associated with infection, severe hospitalized disease and mortality among children older than 6 months and adults on the Kenyan coast is presented. METHODS A prospective fever surveillance was undertaken at 6 out-patients (OPD) health-facilities between March 2018 and February 2019. Four community-based, cross sectional surveys of fever history and infection prevalence were completed among randomly selected homestead members from the same communities. Paediatric and adult malaria at Kilifi county hospital was obtained for the 12 months period. Rapid Diagnostic Tests (CareStart™ RDT) to detect HRP2-specific to Plasmodium falciparum was used in the community and the OPD, and microscopy in the hospital. Crude and age-specific incidence rates were computed using Poisson regression. RESULTS Parasite prevalence gradually increased from childhood, reaching 12% by 9 years of age then declining through adolescence into adulthood. The incidence rate of RDT positivity in the OPD followed a similar trend to that of infection prevalence in the community. The incidence of hospitalized malaria from the same community was concentrated among children aged 6 months to 4 years (i.e. 64% and 70% of all hospitalized and severe malaria during the 12 months of surveillance, respectively). Only 3.7% (12/316) of deaths were directly attributable to malaria. Malaria mortality was highest among children aged 6 months-4 years at 0.57 per 1000 person-years (95% CI 0.2, 1.2). Severe malaria and death from malaria was negligible above 15 years of age. CONCLUSION Under conditions of low transmission intensity, immunity to disease and the fatal consequences of infection appear to continue to be acquired in childhood and faster than anti-parasitic immunity. There was no evidence of an emerging significant burden of severe malaria or malaria mortality among adults. This is contrary to current modelled approaches to disease burden estimation in Africa and has important implications for the targeting of infection prevention strategies based on chemoprevention or vector control.
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Affiliation(s)
- Alice Kamau
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
| | - Grace Mtanje
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Christine Mataza
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Ministry of Health, Kilifi County Government, Kilifi, Kenya
| | | | - Neema Mturi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Gideon Nyutu
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Amek Nyaguara
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Robert W Snow
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
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Achan J, Reuling IJ, Yap XZ, Dabira E, Ahmad A, Cox M, Nwakanma D, Tetteh K, Wu L, Bastiaens GJH, Abebe Y, Manoj A, Kaur H, Miura K, Long C, Billingsley PF, Sim BKL, Hoffman SL, Drakeley C, Bousema T, D’Alessandro U. Serologic Markers of Previous Malaria Exposure and Functional Antibodies Inhibiting Parasite Growth Are Associated With Parasite Kinetics Following a Plasmodium falciparum Controlled Human Infection. Clin Infect Dis 2020; 70:2544-2552. [PMID: 31402382 PMCID: PMC7286377 DOI: 10.1093/cid/ciz740] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 08/01/2019] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND We assessed the impact of exposure to Plasmodium falciparum on parasite kinetics, clinical symptoms, and functional immunity after controlled human malaria infection (CHMI) in 2 cohorts with different levels of previous malarial exposure. METHODS Nine adult males with high (sero-high) and 10 with low (sero-low) previous exposure received 3200 P. falciparum sporozoites (PfSPZ) of PfSPZ Challenge by direct venous inoculation and were followed for 35 days for parasitemia by thick blood smear (TBS) and quantitative polymerase chain reaction. Endpoints were time to parasitemia, adverse events, and immune responses. RESULTS Ten of 10 (100%) volunteers in the sero-low and 7 of 9 (77.8%) in the sero-high group developed parasitemia detected by TBS in the first 28 days (P = .125). The median time to parasitemia was significantly shorter in the sero-low group than the sero-high group (9 days [interquartile range {IQR} 7.5-11.0] vs 11.0 days [IQR 7.5-18.0], respectively; log-rank test, P = .005). Antibody recognition of sporozoites was significantly higher in the sero-high (median, 17.93 [IQR 12.95-24] arbitrary units [AU]) than the sero-low volunteers (median, 10.54 [IQR, 8.36-12.12] AU) (P = .006). Growth inhibitory activity was significantly higher in the sero-high (median, 21.8% [IQR, 8.15%-29.65%]) than in the sero-low group (median, 8.3% [IQR, 5.6%-10.23%]) (P = .025). CONCLUSIONS CHMI was safe and well tolerated in this population. Individuals with serological evidence of higher malaria exposure were able to better control infection and had higher parasite growth inhibitory activity. CLINICAL TRIALS REGISTRATION NCT03496454.
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Affiliation(s)
- Jane Achan
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Isaie J Reuling
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Xi Zen Yap
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Edgard Dabira
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Abdullahi Ahmad
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Momodou Cox
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Davis Nwakanma
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Kevin Tetteh
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Lindsey Wu
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Guido J H Bastiaens
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | - Harparkash Kaur
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
| | - Carole Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
| | | | | | | | - Chris Drakeley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Umberto D’Alessandro
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
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Suh E, Grossman MK, Waite JL, Dennington NL, Sherrard-Smith E, Churcher TS, Thomas MB. The influence of feeding behaviour and temperature on the capacity of mosquitoes to transmit malaria. Nat Ecol Evol 2020; 4:940-951. [PMID: 32367033 PMCID: PMC7334094 DOI: 10.1038/s41559-020-1182-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 03/20/2020] [Indexed: 12/23/2022]
Abstract
Insecticide-treated bed nets reduce malaria transmission by limiting contact between mosquito vectors and human hosts when mosquitoes feed during the night. However, malaria vectors can also feed in the early evening and in the morning when people are not protected. Here, we explored how the timing of blood feeding interacts with environmental temperature to influence the capacity of Anopheles mosquitoes to transmit the human malaria parasite Plasmodium falciparum. In laboratory experiments, we found no effect of biting time itself on the proportion of mosquitoes that became infectious (vector competence) at constant temperature. However, when mosquitoes were maintained under more realistic fluctuating temperatures, there was a significant increase in competence for mosquitoes feeding in the evening (18:00), and a significant reduction in competence for those feeding in the morning (06:00), relative to those feeding at midnight (00:00). These effects appear to be due to thermal sensitivity of malaria parasites during the initial stages of parasite development within the mosquito, and the fact that mosquitoes feeding in the evening experience cooling temperatures during the night, whereas mosquitoes feeding in the morning quickly experience warming temperatures that are inhibitory to parasite establishment. A transmission dynamics model illustrates that such differences in competence could have important implications for malaria prevalence, the extent of transmission that persists in the presence of bed nets, and the epidemiological impact of behavioural resistance. These results indicate that the interaction of temperature and feeding behaviour could be a major ecological determinant of the vectorial capacity of malaria mosquitoes.
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Affiliation(s)
- Eunho Suh
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA.
| | - Marissa K Grossman
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA
| | - Jessica L Waite
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA.,Green Mountain Antibodies, Burlington, VT, USA
| | - Nina L Dennington
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Matthew B Thomas
- Center for Infectious Disease Dynamics, Department of Entomology, Penn State University, University Park, PA, USA
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Anyona SB, Hengartner NW, Raballah E, Ong'echa JM, Lauve N, Cheng Q, Fenimore PW, Ouma C, Lambert CG, McMahon BH, Perkins DJ. Cyclooxygenase-2 haplotypes influence the longitudinal risk of malaria and severe malarial anemia in Kenyan children from a holoendemic transmission region. J Hum Genet 2020; 65:99-113. [PMID: 31664161 PMCID: PMC7255056 DOI: 10.1038/s10038-019-0692-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 09/16/2019] [Accepted: 10/09/2019] [Indexed: 02/08/2023]
Abstract
Cyclooxygenase-2 [(COX-2) or prostaglandin endoperoxide H2 synthase-2 (PTGS-2)] induces the production of prostaglandins as part of the host-immune response to infections. Although a number of studies have demonstrated the effects of COX-2 promoter variants on autoimmune and inflammatory diseases, their role in malaria remains undefined. As such, we investigated the relationship between four COX-2 promoter variants (COX-2 -512 C > T, -608 T > C, -765 G > C, and -1195 A > G) and susceptibility to malaria and severe malarial anemia (SMA) upon enrollment and longitudinally over a 36-month follow-up period. All-cause mortality was also explored. The investigation was carried out in children (n = 1081, age; 2-70 months) residing in a holoendemic Plasmodium falciparum transmission region of western Kenya. At enrollment, genotypes/haplotypes (controlling for anemia-promoting covariates) did not reveal any strong effects on susceptibility to either malaria or SMA. Longitudinal analyses showed decreased malaria episodes in children who inherited the -608 CC mutant allele (RR = 0.746, P = 1.811 × 10-4) and -512C/-608T/-765G/-1195G (CTGG) haplotype (RR = 0.856, P = 0.011), and increased risk in TTCA haplotype carriers (RR = 1.115, P = 0.026). Over the follow-up period, inheritance of the rare TTCG haplotype was associated with enhanced susceptibility to both malaria (RR = 1.608, P = 0.016) and SMA (RR = 5.714, P = 0.004), while carriage of the rare TTGG haplotype increased the risk of malaria (RR = 1.755, P = 0.007), SMA (RR = 8.706, P = 3.97 × 10-4), and all-cause mortality (HR = 110.000, P = 0.001). Collectively, these results show that SNP variations in the COX-2 promoter, and their inherited combinations, are associated with the longitudinal risk of malaria, SMA, and all-cause mortality among children living in a high transmission area for P. falciparum.
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Affiliation(s)
- Samuel B Anyona
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya
- Department of Medical Biochemistry, School of Medicine, Maseno University, Maseno, Kenya
| | - Nicolas W Hengartner
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Evans Raballah
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya
- Department of Medical Laboratory Sciences, School of Public Health Biomedical Sciences and Technology, Masinde Muliro University of Science and Technology, Kakamega, Kenya
| | | | - Nick Lauve
- Center for Global Health, University of New Mexico, Albuquerque, NM, USA
| | - Qiuying Cheng
- Center for Global Health, University of New Mexico, Albuquerque, NM, USA
| | - Paul W Fenimore
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Collins Ouma
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya
- Department of Biomedical Sciences and Technology, School of Public Health and Community Development, Maseno University, Maseno, Kenya
| | | | - Benjamin H McMahon
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Douglas J Perkins
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya.
- Center for Global Health, University of New Mexico, Albuquerque, NM, USA.
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Kale S, Yadav CP, Rao PN, Shalini S, Eapen A, Srivasatava HC, Sharma SK, Pande V, Carlton JM, Singh OP, Mallick PK. Antibody responses within two leading Plasmodium vivax vaccine candidate antigens in three geographically diverse malaria-endemic regions of India. Malar J 2019; 18:425. [PMID: 31842894 PMCID: PMC6916228 DOI: 10.1186/s12936-019-3066-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 12/08/2019] [Indexed: 01/28/2023] Open
Abstract
Background Identifying highly immunogenic blood stage antigens which can work as target for naturally acquired antibodies in different eco-epidemiological settings is an important step for designing malaria vaccine. Blood stage proteins of Plasmodium vivax, apical membrane antigen-1 (PvAMA-1) and 19 kDa fragment of merozoite surface protein (PvMSP-119) are such promising vaccine candidate antigens. This study determined the naturally-acquired antibody response to PvAMA-1 and PvMSP-119 antigens in individuals living in three geographically diverse malaria endemic regions of India. Methods A total of 234 blood samples were collected from individuals living in three different eco-epidemiological settings, Chennai, Nadiad, and Rourkela of India. Indirect ELISA was performed to measure human IgG antibodies against recombinant PvAMA-1 and PvMSP-119 antigens. The difference in seroprevalence and factors associated with antibody responses at each site was statistically analysed. Results The overall seroprevalence was 40.6% for PvAMA-1 and 62.4% for PvMSP-119. Seroprevalence to PvAMA-1 was higher in Chennai (47%) followed by Nadiad (46.7%) and Rourkela (27.6%). For PvMSP-119, seroprevalence was higher in Chennai (80.3%) as compared to Nadiad (53.3%) and Rourkela (57.9%). Seroprevalence for both the antigens were found to be higher in Chennai where P. vivax is the dominant malaria species. In addition, heterogeneous antibody response was observed for PvAMA-1 and PvMSP-119 antigens at each of the study sites. Two factors, age and malaria positivity were significantly associated with seropositivity for both the antigens PvAMA-1 and PvMSP-119. Conclusion These data suggest that natural acquired antibody response is higher for PvMSP-119 antigen as compared to PvAMA-1 antigen in individuals living in three geographically diverse malaria endemic regions in India. PvMSP-119 appears to be highly immunogenic in Indian population and has great potential as a malaria vaccine candidate. The differences in immune response against vaccine candidate antigens in different endemic settings should be taken into account for development of asexual stage based P. vivax malaria vaccine, which in turn can enhance malaria control efforts.
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Affiliation(s)
- Sonal Kale
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India.,Department of Biotechnology, Kumaun University, Nainital, Uttarakhand, India
| | - Chander P Yadav
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India
| | - Pavitra N Rao
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, USA
| | - Sneh Shalini
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India
| | - Alex Eapen
- National Institute of Malaria Research Field Unit, Indian Council of Medical Research, National Institute of Epidemiology Campus, Ayapakkam, Chennai, Tamil Nadu, India
| | - Harish C Srivasatava
- National Institute of Malaria Research Field Unit, Civil Hospital, Nadiad, Gujarat, India
| | - Surya K Sharma
- Jigyansha, International Center of Excellence for Malaria Research, Sector 1, Rourkela, Odisha, India
| | - Veena Pande
- Department of Biotechnology, Kumaun University, Nainital, Uttarakhand, India
| | - Jane M Carlton
- Department of Biology, Center for Genomics and Systems Biology, New York University, New York, USA
| | - Om P Singh
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India.
| | - Prashant K Mallick
- ICMR-National Institute of Malaria Research, Sector 8, Dwarka, New Delhi, India.
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Barrier bednets target malaria vectors and expand the range of usable insecticides. Nat Microbiol 2019; 5:40-47. [PMID: 31792426 DOI: 10.1038/s41564-019-0607-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 10/11/2019] [Indexed: 11/08/2022]
Abstract
Transmission of Plasmodium falciparum malaria parasites occurs when nocturnal Anopheles mosquito vectors feed on human blood. In Africa, where malaria burden is highest, bednets treated with pyrethroid insecticide were highly effective in preventing mosquito bites and reducing transmission, and essential to achieving unprecedented reductions in malaria until 2015 (ref. 1). Since then, progress has stalled2, and with insecticidal bednets losing efficacy against pyrethroid-resistant Anopheles vectors3,4, methods that restore performance are urgently needed to eliminate any risk of malaria returning to the levels seen before their widespread use throughout sub-Saharan Africa5. Here, we show that the primary malaria vector Anopheles gambiae is targeted and killed by small insecticidal net barriers positioned above a standard bednet in a spatial region of high mosquito activity but zero contact with sleepers, opening the way for deploying many more insecticides on bednets than is currently possible. Tested against wild pyrethroid-resistant A. gambiae in Burkina Faso, pyrethroid bednets with organophosphate barriers achieved significantly higher killing rates than bednets alone. Treated barriers on untreated bednets were equally effective, without significant loss of personal protection. Mathematical modelling of transmission dynamics predicted reductions in clinical malaria incidence with barrier bednets that matched those of 'next-generation' nets recommended by the World Health Organization against resistant vectors. Mathematical models of mosquito-barrier interactions identified alternative barrier designs to increase performance. Barrier bednets that overcome insecticide resistance are feasible using existing insecticides and production technology, and early implementation of affordable vector control tools is a realistic prospect.
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28
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Achieng AO, Hengartner NW, Raballah E, Cheng Q, Anyona SB, Lauve N, Guyah B, Foo-Hurwitz I, Ong'echa JM, McMahon BH, Ouma C, Lambert CG, Perkins DJ. Integrated OMICS platforms identify LAIR1 genetic variants as novel predictors of cross-sectional and longitudinal susceptibility to severe malaria and all-cause mortality in Kenyan children. EBioMedicine 2019; 45:290-302. [PMID: 31278068 PMCID: PMC6642287 DOI: 10.1016/j.ebiom.2019.06.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 06/19/2019] [Accepted: 06/20/2019] [Indexed: 01/05/2023] Open
Abstract
Background Severe malarial anaemia (SMA) is a leading cause of childhood mortality in holoendemic Plasmodium falciparum regions. Methods To gain an improved understanding of SMA pathogenesis, whole genome and transcriptome profiling was performed in Kenyan children (n = 144, 3–36 months) with discrete non-SMA and SMA phenotypes. Leukocyte associated immunoglobulin like receptor 1 (LAIR1) emerged as a predictor of susceptibility to SMA (P < 1 × 10−2, OR: 0.44–1.37), and was suppressed in severe disease (−1.69-fold, P = 0.004). To extend these findings, the relationship between LAIR1 polymorphisms [rs6509867 (16231C>A); rs2287827 (18835G>A)] and clinical outcomes were investigated in individuals (n = 1512, <5 years) at enrolment and during a 36-month longitudinal follow-up. Findings Inheritance of the 16,231 recessive genotype (AA) increased susceptibility to SMA at enrolment (OR = 1.903, 95%CI: 1.252–2.891, P = 0.003), and longitudinally (RR = 1.527, 95%CI: 1.119–2.083, P = 0.008). Carriage of the 18,835 GA genotype protected against SMA cross-sectionally (OR = 0.672, 95%CI: 0.480–0.9439, P = 0.020). Haplotype carriage (C16231A/G18835A) also altered cross-sectional susceptibility to SMA: CG (OR = 0.717, 95%CI: 0.527–0.9675, P = 0.034), CA (OR = 0.745, 95%CI: 0.536–1.036, P = 0.080), and AG (OR = 1.641, 95%CI: 1.160–2.321, P = 0.005). Longitudinally, CA carriage was protective against SMA (RR = 0.715, 95%CI: 0.554–0.923, P = 0.010), while AG carriage had an additive effect on enhanced SMA risk (RR = 1.283, 95%CI: 1.057–1.557, P = 0.011). Variants that protected against SMA had elevated LAIR1 transcripts, while those with enhanced risk had lower expression (P < 0.05). Inheritance of 18,835 GA reduced all-cause mortality by 44.8% (HR = 0.552, 95%CI: 0.329–0.925, P = 0.024), while AG haplotype carriage increased susceptibility by 68% (HR = 1.680, 95%CI: 1.020–2.770, P = 0.040). Interpretation These findings suggest LAIR1 is important for modulating susceptibility to SMA and all-cause childhood mortality.
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Affiliation(s)
- Angela O Achieng
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya; Department of Biomedical Sciences and Technology, School of Public Health and Community Development, Maseno University, Maseno, Kenya
| | - Nicolas W Hengartner
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Evans Raballah
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya; Department of Medical Laboratory Sciences, School of Public Health Biomedical Sciences and Technology, Masinde Muliro University of Science and Technology, Kakamega, Kenya
| | - Qiuying Cheng
- University of New Mexico, Center for Global Health, Department of Internal Medicine, NM, USA
| | - Samuel B Anyona
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya; Department of Medical Biochemistry, School of Medicine, Maseno University, Maseno, Kenya
| | - Nick Lauve
- University of New Mexico, Center for Global Health, Department of Internal Medicine, NM, USA
| | - Bernard Guyah
- Department of Biomedical Sciences and Technology, School of Public Health and Community Development, Maseno University, Maseno, Kenya
| | - Ivy Foo-Hurwitz
- University of New Mexico, Center for Global Health, Department of Internal Medicine, NM, USA
| | - John M Ong'echa
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Benjamin H McMahon
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Collins Ouma
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya; Department of Biomedical Sciences and Technology, School of Public Health and Community Development, Maseno University, Maseno, Kenya
| | - Christophe G Lambert
- University of New Mexico, Center for Global Health, Department of Internal Medicine, NM, USA
| | - Douglas J Perkins
- University of New Mexico-Kenya Global Health Programs, Kisumu and Siaya, Kenya; University of New Mexico, Center for Global Health, Department of Internal Medicine, NM, USA.
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Patel H, Althubaiti N, Parmar R, Yadav N, Joshi U, Tyagi RK, Krzych U, Dalai SK. Parasite load stemming from immunization route determines the duration of liver-stage immunity. Parasite Immunol 2019; 41:e12622. [PMID: 30854655 PMCID: PMC6584043 DOI: 10.1111/pim.12622] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 12/28/2018] [Accepted: 02/22/2019] [Indexed: 02/05/2023]
Abstract
Immunization with radiation-attenuated Plasmodium sporozoites (RAS) induces sterile and long-lasting protective immunity. Although intravenous (IV) route of RAS immunization is reported to induce superior immunity compared to intradermal (ID) injection, its role in the maintenance of sterile immunity is yet to be understood. We investigated whether the route of homologous sporozoite challenge of Plasmodium berghei (Pb) RAS-immunized mice would influence the longevity of protection. C57BL/6 mice immunized with Pb-RAS by IV were 100% protected upon primary IV/ID sporozoite challenge. In contrast, ID immunization resulted in 80% protection, regardless of primary challenge route. Interestingly, the route of primary challenge was found to bring difference in the maintenance of sterile protection. While IV Pb RAS-immunized mice remained protected at all challenges regardless of the route of primary challenge, ID Pb-RAS-immunized mice receiving ID primary challenge became parasitaemic upon secondary IV challenge. Significantly, primary IV challenge of Pb RAS ID-immunized mice resulted in 80% and 50% survival at secondary and tertiary challenges, respectively. According to phenotypically diverse liver CD8+ T cells, the percentages and the numbers of both CD8+ T effector memory and resident memory cells were significantly higher in IV than in ID Pb RAS-immunized mice. IFN-γ-producing CD8+ T cells specific to Pb TRAP130 and MIP-4-Kb-17 were also found significantly higher in IV mice than in ID mice. The enhanced T-cell generation and the longevity of protection appear to be dependent on the parasite load during challenge when infection is tolerated under suboptimal CD8+ T-cell response.
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Affiliation(s)
- Hardik Patel
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India
| | - Nouf Althubaiti
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Rajesh Parmar
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India
| | - Naveen Yadav
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India
| | - Urja Joshi
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India
| | - Rajeev K Tyagi
- Institute of Science, Nirma University, Ahmedabad, Gujarat, India
| | - Urszula Krzych
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - Sarat K Dalai
- Department of Cellular Immunology, Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, MD, USA
- Correspondence: Sarat Kumar Dalai, Institute of Science, Nirma University, Sarkhej-Gandhinagar Highway, Ahmedabad 382 481, Gujarat, India,
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Maurizio PL, Fuseini H, Tegha G, Hosseinipour M, De Paris K. Signatures of divergent anti-malarial treatment responses in peripheral blood from adults and young children in Malawi. Malar J 2019; 18:205. [PMID: 31234875 PMCID: PMC6591936 DOI: 10.1186/s12936-019-2842-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 06/17/2019] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Heterogeneity in the immune response to parasite infection is mediated in part by differences in host genetics, gender, and age group. In infants and young children, ongoing immunological maturation often results in increased susceptibility to infection and variable responses to drug treatment, increasing the risk of complications. Even though significant age-associated effects on host cytokine responses to Plasmodium falciparum infection have been identified, age-associated effects on uncomplicated malaria infection and anti-malarial treatment remain poorly understood. METHODS In samples of whole blood from a cohort of naturally infected malaria-positive individuals with non-severe falciparum malaria in Malawi (n = 63 total; 34 infants and young children < 2 years old, 29 adults > 18 years old), blood cytokine levels and monocyte and dendritic cell frequencies were assessed at two timepoints: acute infection, and 4 weeks post anti-malarial treatment. The effects of age group, gender, and timepoint were modeled, and the role of these factors on infection and treatment outcomes was evaluated. RESULTS Regardless of treatment timepoint, in this population age was significantly associated with overall blood haemoglobin, which was higher in adults, and plasma nitric oxide metabolites, IL-10, and TNF levels, which were higher in young children. There was a significant effect of age on the haemoglobin treatment response, whereby after treatment, levels increased in young children and decreased in adults. Furthermore, there were significant age-associated effects on treatment response for overall parasite load, IFN-γ, and IL-12(p40), and these effects were gender-dependent. Significant age effects on the overall levels and treatment response of myeloid dendritic cell frequencies were observed. In addition, within each age group, results showed continuous age effects on gametocyte levels (Pfs16), TNF, and nitric oxide metabolites. CONCLUSIONS In a clinical study of young children and adults experiencing natural falciparum malaria infection and receiving anti-malarial treatment, age-associated signatures of infection and treatment responses in peripheral blood were identified. This study describes host markers that may indicate, and potentially contribute to, differential post-treatment outcomes for malaria in young children versus adults.
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Affiliation(s)
- Paul L Maurizio
- Department of Medicine, Section of Genetic Medicine, The University of Chicago, Chicago, IL, 60637, USA.
- Department of Genetics, University of North Carolina-Chapel Hill, Chapel Hill, NC, 27599, USA.
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina-Chapel Hill, Chapel Hill, NC, 27599, USA.
| | - Hubaida Fuseini
- Department of Pathology, Microbiology & Immunology, Vanderbilt University, Nashville, TN, USA
| | - Gerald Tegha
- Division of Infectious Diseases, Department of Medicine, University of North Carolina, 130 Mason Farm Rd, Bioinformatics Bldg, Chapel Hill, NC, 27599, USA
| | - Mina Hosseinipour
- Division of Infectious Diseases, Department of Medicine, University of North Carolina, 130 Mason Farm Rd, Bioinformatics Bldg, Chapel Hill, NC, 27599, USA
- University of North Carolina Project-Malawi, Lilongwe, Malawi
| | - Kristina De Paris
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, 27599, USA
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Modelling pathogen load dynamics to elucidate mechanistic determinants of host-Plasmodium falciparum interactions. Nat Microbiol 2019; 4:1592-1602. [PMID: 31209307 PMCID: PMC6708439 DOI: 10.1038/s41564-019-0474-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 04/30/2019] [Indexed: 12/21/2022]
Abstract
During infection, increasing pathogen load stimulates both protective and
harmful aspects of the host response. The dynamics of this interaction are hard
to quantify in humans, but doing so could improve understanding of mechanisms of
disease and protection. We sought to model the contributions of parasite
multiplication rate and host response to observed parasite load in individual
subjects with Plasmodium falciparum malaria, using only data
obtained at the time of clinical presentation, and then to identify their
mechanistic correlates. We predicted higher parasite multiplication rates and
lower host responsiveness in severe malaria cases, with severe anemia being more
insidious than cerebral malaria. We predicted that parasite growth-inhibition
was associated with platelet consumption, lower expression of
CXCL10 and type-1 interferon-associated genes, but
increased cathepsin G and matrix metallopeptidase 9 expression. We found that
cathepsin G and matrix metallopeptidase 9 directly inhibit parasite invasion
into erythrocytes. Parasite multiplication rate was associated with host iron
availability and higher complement factor H levels, lower expression of
gametocyte-associated genes but higher expression of translation-associated
genes in the parasite. Our findings demonstrate the potential of using explicit
modelling of pathogen load dynamics to deepen understanding of host-pathogen
interactions and identify mechanistic correlates of protection.
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Winskill P, Walker PG, Cibulskis RE, Ghani AC. Prioritizing the scale-up of interventions for malaria control and elimination. Malar J 2019; 18:122. [PMID: 30961603 PMCID: PMC6454681 DOI: 10.1186/s12936-019-2755-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 03/29/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A core set of intervention and treatment options are recommended by the World Health Organization for use against falciparum malaria. These are treatment, long-lasting insecticide-treated bed nets, indoor residual spraying, and chemoprevention options. Both domestic and foreign aid funding for these tools is limited. When faced with budget restrictions, the introduction and scale-up of intervention and treatment options must be prioritized. METHODS Estimates of the cost and impact of different interventions were combined with a mathematical model of malaria transmission to estimate the most cost-effective prioritization of interventions. The incremental cost effectiveness ratio was used to select between scaling coverage of current interventions or the introduction of an additional intervention tool. RESULTS Prevention, in the form of vector control, is highly cost effective and scale-up is prioritized in all scenarios. Prevention reduces malaria burden and therefore allows treatment to be implemented in a more cost-effective manner by reducing the strain on the health system. The chemoprevention measures (seasonal malaria chemoprevention and intermittent preventive treatment in infants) are additional tools that, provided sufficient funding, are implemented alongside treatment scale-up. Future tools, such as RTS,S vaccine, have impact in areas of higher transmission but were introduced later than core interventions. CONCLUSIONS In a programme that is budget restricted, it is essential that investment in available tools be effectively prioritized to maximize impact for a given investment. The cornerstones of malaria control: vector control and treatment, remain vital, but questions of when to scale and when to introduce other interventions must be rigorously assessed. This quantitative analysis considers the scale-up or core interventions to inform decision making in this area.
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Affiliation(s)
- Peter Winskill
- MRC Centre of Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, London, W2 1PG, UK.
| | - Patrick G Walker
- MRC Centre of Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, London, W2 1PG, UK
| | | | - Azra C Ghani
- MRC Centre of Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, London, W2 1PG, UK
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Abstract
A single exposure to many viral and bacterial pathogens typically induces life-long immunity, however, the development of the protective immunity to Plasmodium parasites is strikingly less efficient and achieves only partial protection, with adults residing in endemic areas often experiencing asymptomatic infections. Although naturally acquired immunity to malaria requires both cell-mediated and humoral immune responses, antibodies govern the control of malarial disease caused by the blood-stage form of the parasites. A large body of epidemiological evidence described that antibodies to Plasmodium antigens are inefficiently generated and rapidly lost without continued parasite exposure, suggesting that malaria is accompanied by defects in the development of immunological B cell memory. This topic has been of focus of recent studies of malaria infection in humans and mice. This review examines the main findings to date on the processes that modulate the acquisition of memory B cell responses to malaria, and highlights the importance of closing outstanding gaps of knowledge in the field for the rational design of next generation therapeutics against malaria.
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Affiliation(s)
- Ann Ly
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Diana S Hansen
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
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Shaw TN, Inkson CA, Villegas-Mendez A, Pattinson DJ, Strangward P, Else KJ, Draper SJ, Zeef LAH, Couper KN. Infection-Induced Resistance to Experimental Cerebral Malaria Is Dependent Upon Secreted Antibody-Mediated Inhibition of Pathogenic CD8 + T Cell Responses. Front Immunol 2019; 10:248. [PMID: 30846985 PMCID: PMC6394254 DOI: 10.3389/fimmu.2019.00248] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 01/29/2019] [Indexed: 12/27/2022] Open
Abstract
Cerebral malaria (CM) is one of the most severe complications of Plasmodium falciparum infection. There is evidence that repeated parasite exposure promotes resistance against CM. However, the immunological basis of this infection-induced resistance remains poorly understood. Here, utilizing the Plasmodium berghei ANKA (PbA) model of experimental cerebral malaria (ECM), we show that three rounds of infection and drug-cure protects against the development of ECM during a subsequent fourth (4X) infection. Exposure-induced resistance was associated with specific suppression of CD8+ T cell activation and CTL-related pathways, which corresponded with the development of heterogeneous atypical B cell populations as well as the gradual infection-induced generation and maintenance of high levels of anti-parasite IgG. Mechanistically, transfer of high-titer anti-parasite IgG did not protect 1X infected mice against ECM and depletion of atypical and regulatory B cells during 4X infection failed to abrogate infection-induced resistance to ECM. However, IgMi mice that were unable to produce secreted antibody, or undergo class switching, during the repeated rounds of infection failed to develop resistance against ECM. The failure of infection-induced protection in IgMi mice was associated with impaired development of atypical B cell populations and the inability to suppress pathogenic CD8+ T cell responses. Our results, therefore, suggest the importance of anti-parasite antibody responses, gradually acquired, and maintained through repeated Plasmodium infections, for modulating the B cell compartment and eventually suppressing memory CD8+ T cell reactivation to establish infection-induced resistance to ECM.
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Affiliation(s)
- Tovah N. Shaw
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
- Manchester Collaborative Centre for Inflammation Research, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Colette A. Inkson
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Ana Villegas-Mendez
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | | | - Patrick Strangward
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Kathryn J. Else
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
| | - Simon J. Draper
- The Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Leo A. H. Zeef
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Kevin N. Couper
- Faculty of Biology, Medicine and Health, The Lydia Becker Institute of Immunology and Inflammation, University of Manchester, Manchester, United Kingdom
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35
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Chan JA, Boyle MJ, Moore KA, Reiling L, Lin Z, Hasang W, Avril M, Manning L, Mueller I, Laman M, Davis T, Smith JD, Rogerson SJ, Simpson JA, Fowkes FJI, Beeson JG. Antibody Targets on the Surface of Plasmodium falciparum-Infected Erythrocytes That Are Associated With Immunity to Severe Malaria in Young Children. J Infect Dis 2019; 219:819-828. [PMID: 30365004 PMCID: PMC6376912 DOI: 10.1093/infdis/jiy580] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/15/2018] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Sequestration of Plasmodium falciparum-infected erythrocytes (IEs) in the microvasculature contributes to pathogenesis of severe malaria in children. This mechanism is mediated by antigens expressed on the IE surface. However, knowledge of specific targets and functions of antibodies to IE surface antigens that protect against severe malaria is limited. METHODS Antibodies to IE surface antigens were examined in a case-control study of young children in Papua New Guinea presenting with severe or uncomplicated malaria (n = 448), using isolates with a virulent phenotype associated with severe malaria, and functional opsonic phagocytosis assays. We used genetically modified isolates and recombinant P. falciparum erythrocyte membrane protein 1 (PfEMP1) domains to quantify PfEMP1 as a target of antibodies associated with disease severity. RESULTS Antibodies to the IE surface and recombinant PfEMP1 domains were significantly higher in uncomplicated vs severe malaria and were boosted following infection. The use of genetically modified P. falciparum revealed that PfEMP1 was a major target of antibodies and that PfEMP1-specific antibodies were associated with reduced odds of severe malaria. Furthermore, antibodies promoting the opsonic phagocytosis of IEs by monocytes were lower in those with severe malaria. CONCLUSIONS Findings suggest that PfEMP1 is a dominant target of antibodies associated with reduced risk of severe malaria, and function in part by promoting opsonic phagocytosis.
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Affiliation(s)
- Jo-Anne Chan
- Burnet Institute for Medical Research and Public Health, Melbourne
| | - Michelle J Boyle
- Burnet Institute for Medical Research and Public Health, Melbourne
| | - Kerryn A Moore
- Burnet Institute for Medical Research and Public Health, Melbourne
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Parkville
- Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne
| | - Linda Reiling
- Burnet Institute for Medical Research and Public Health, Melbourne
| | - Zaw Lin
- Burnet Institute for Medical Research and Public Health, Melbourne
| | - Wina Hasang
- Department of Medicine, Melbourne School of Population and Global Health, University of Melbourne, Parkville, Australia
| | - Marion Avril
- Center for Infectious Diseases Research, Seattle, Washington
| | - Laurens Manning
- Papua New Guinea Institute of Medical Research, Madang
- University of Western Australia, Perth
| | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research, Parkville
| | - Moses Laman
- Papua New Guinea Institute of Medical Research, Madang
| | | | - Joseph D Smith
- Center for Infectious Diseases Research, Seattle, Washington
| | - Stephen J Rogerson
- Department of Medicine, Melbourne School of Population and Global Health, University of Melbourne, Parkville, Australia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Parkville
| | - Freya J I Fowkes
- Burnet Institute for Medical Research and Public Health, Melbourne
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Parkville
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia
- Department of Infectious Diseases, Monash University, Melbourne, Victoria, Australia
| | - James G Beeson
- Burnet Institute for Medical Research and Public Health, Melbourne
- Department of Medicine, Melbourne School of Population and Global Health, University of Melbourne, Parkville, Australia
- Department of Microbiology, Monash University, Melbourne, Victoria, Australia
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Systematic review of indoor residual spray efficacy and effectiveness against Plasmodium falciparum in Africa. Nat Commun 2018; 9:4982. [PMID: 30478327 PMCID: PMC6255894 DOI: 10.1038/s41467-018-07357-w] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/25/2018] [Indexed: 11/08/2022] Open
Abstract
Indoor residual spraying (IRS) is an important part of malaria control. There is a growing list of insecticide classes; pyrethroids remain the principal insecticide used in bednets but recently, novel non-pyrethroid IRS products, with contrasting impacts, have been introduced. There is an urgent need to better assess product efficacy to help decision makers choose effective and relevant tools for mosquito control. Here we use experimental hut trial data to characterise the entomological efficacy of widely-used, novel IRS insecticides. We quantify their impact against pyrethroid-resistant mosquitoes and use a Plasmodium falciparum transmission model to predict the public health impact of different IRS insecticides. We report that long-lasting IRS formulations substantially reduce malaria, though their benefit over cheaper, shorter-lived formulations depends on local factors including bednet use, seasonality, endemicity and pyrethroid resistance status of local mosquito populations. We provide a framework to help decision makers evaluate IRS product effectiveness.
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Smith NR, Trauer JM, Gambhir M, Richards JS, Maude RJ, Keith JM, Flegg JA. Agent-based models of malaria transmission: a systematic review. Malar J 2018; 17:299. [PMID: 30119664 PMCID: PMC6098619 DOI: 10.1186/s12936-018-2442-y] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 08/04/2018] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Much of the extensive research regarding transmission of malaria is underpinned by mathematical modelling. Compartmental models, which focus on interactions and transitions between population strata, have been a mainstay of such modelling for more than a century. However, modellers are increasingly adopting agent-based approaches, which model hosts, vectors and/or their interactions on an individual level. One reason for the increasing popularity of such models is their potential to provide enhanced realism by allowing system-level behaviours to emerge as a consequence of accumulated individual-level interactions, as occurs in real populations. METHODS A systematic review of 90 articles published between 1998 and May 2018 was performed, characterizing agent-based models (ABMs) relevant to malaria transmission. The review provides an overview of approaches used to date, determines the advantages of these approaches, and proposes ideas for progressing the field. RESULTS The rationale for ABM use over other modelling approaches centres around three points: the need to accurately represent increased stochasticity in low-transmission settings; the benefits of high-resolution spatial simulations; and heterogeneities in drug and vaccine efficacies due to individual patient characteristics. The success of these approaches provides avenues for further exploration of agent-based techniques for modelling malaria transmission. Potential extensions include varying elimination strategies across spatial landscapes, extending the size of spatial models, incorporating human movement dynamics, and developing increasingly comprehensive parameter estimation and optimization techniques. CONCLUSION Collectively, the literature covers an extensive array of topics, including the full spectrum of transmission and intervention regimes. Bringing these elements together under a common framework may enhance knowledge of, and guide policies towards, malaria elimination. However, because of the diversity of available models, endorsing a standardized approach to ABM implementation may not be possible. Instead it is recommended that model frameworks be contextually appropriate and sufficiently described. One key recommendation is to develop enhanced parameter estimation and optimization techniques. Extensions of current techniques will provide the robust results required to enhance current elimination efforts.
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Affiliation(s)
- Neal R Smith
- School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia.
| | - James M Trauer
- School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
| | - Manoj Gambhir
- School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia
- IBM Research Australia, Melbourne, Australia
| | - Jack S Richards
- Life Sciences, Burnet Institute, Melbourne, Australia
- Department of Medicine, University of Melbourne, Parkville, Australia
- Department of Infectious Diseases, Monash University, Melbourne, Australia
| | - Richard J Maude
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Harvard TH Chan School of Public Health, Harvard University, Boston, USA
| | - Jonathan M Keith
- School of Mathematical Sciences, Monash University, Clayton, Australia
| | - Jennifer A Flegg
- School of Mathematics and Statistics, University of Melbourne, Parkville, Australia
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38
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Rodriguez-Barraquer I, Arinaitwe E, Jagannathan P, Kamya MR, Rosenthal PJ, Rek J, Dorsey G, Nankabirwa J, Staedke SG, Kilama M, Drakeley C, Ssewanyana I, Smith DL, Greenhouse B. Quantification of anti-parasite and anti-disease immunity to malaria as a function of age and exposure. eLife 2018; 7:35832. [PMID: 30044224 PMCID: PMC6103767 DOI: 10.7554/elife.35832] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 07/15/2018] [Indexed: 01/13/2023] Open
Abstract
Fundamental gaps remain in our understanding of how immunity to malaria develops. We used detailed clinical and entomological data from parallel cohort studies conducted across the malaria transmission spectrum in Uganda to quantify the development of immunity against symptomatic P. falciparum as a function of age and transmission intensity. We focus on: anti-parasite immunity (i.e. ability to control parasite densities) and anti-disease immunity (i.e. ability to tolerate higher parasite densities without fever). Our findings suggest a strong effect of age on both types of immunity, not explained by cumulative-exposure. They also show an independent effect of exposure, where children living in moderate/high transmission settings develop immunity faster as transmission increases. Surprisingly, children in the lowest transmission setting appear to develop immunity more efficiently than those living in moderate transmission settings. Anti-parasite and anti-disease immunity develop in parallel, reducing the probability of experiencing symptomatic malaria upon each subsequent P. falciparum infection.
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Affiliation(s)
- Isabel Rodriguez-Barraquer
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, United States
| | | | | | - Moses R Kamya
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Phillip J Rosenthal
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, United States
| | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, United States
| | | | - Sarah G Staedke
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Maxwell Kilama
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - David L Smith
- Institute of Health Metrics and Evaluation, University of Washington, Seattle, United States
| | - Bryan Greenhouse
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, San Francisco, United States
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39
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Challenges and opportunities in controlling mosquito-borne infections. Nature 2018; 559:490-497. [PMID: 30046071 DOI: 10.1038/s41586-018-0318-5] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 05/24/2018] [Indexed: 11/08/2022]
Abstract
Mosquito-borne diseases remain a major cause of morbidity and mortality across the tropical regions. Despite much progress in the control of malaria, malaria-associated morbidity remains high, whereas arboviruses-most notably dengue-are responsible for a rising burden of disease, even in middle-income countries that have almost completely eliminated malaria. Here I discuss how new interventions offer the promise of considerable future reductions in disease burden. However, I emphasize that intervention programmes need to be underpinned by rigorous trials and quantitative epidemiological analyses. Such analyses suggest that the long-term goal of elimination is more feasible for dengue than for malaria, even if malaria elimination would offer greater overall health benefit to the public.
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40
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Hogan AB, Winskill P, Verity R, Griffin JT, Ghani AC. Modelling population-level impact to inform target product profiles for childhood malaria vaccines. BMC Med 2018; 16:109. [PMID: 30001708 PMCID: PMC6044028 DOI: 10.1186/s12916-018-1095-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 06/05/2018] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND The RTS,S/AS01 vaccine for Plasmodium falciparum malaria demonstrated moderate efficacy in 5-17-month-old children in phase 3 trials, and from 2018, the vaccine will be evaluated through a large-scale pilot implementation program. Work is ongoing to optimise this vaccine, with higher efficacy for a different schedule demonstrated in a phase 2a challenge study. The objective of our study was to investigate the population-level impact of a modified RTS,S/AS01 schedule and dose amount in order to inform the target product profile for a second-generation malaria vaccine. METHODS We used a mathematical modelling approach as the basis for our study. We simulated the changing anti-circumsporozoite antibody titre following vaccination and related the titre to vaccine efficacy. We then implemented this efficacy profile within an individual-based model of malaria transmission. We compared initial efficacy, duration and dose timing, and evaluated the potential public health impact of a modified vaccine in children aged 5-17 months, measuring clinical cases averted in children younger than 5 years. RESULTS In the first decade of delivery, initial efficacy was associated with a higher reduction in childhood clinical cases compared to vaccine duration. This effect was more pronounced in high transmission settings and was due to the efficacy benefit occurring in younger ages where disease burden is highest. However, the low initial efficacy and long duration schedule averted more cases across all age cohorts if a longer time horizon was considered. We observed an age-shifting effect due to the changing immunological profile in higher transmission settings, in scenarios where initial efficacy was higher, and the fourth dose administered earlier. CONCLUSIONS Our findings indicate that, for an imperfect childhood malaria vaccine with suboptimal efficacy, it may be advantageous to prioritise initial efficacy over duration. We predict that a modified vaccine could outperform the current RTS,S/AS01, although fourth dose timing will affect the age group that derives the greatest benefit. Further, the outcome measure and timeframe over which a vaccine is assessed are important when prioritising vaccine elements. This study provides insight into the most important characteristics of a malaria vaccine for at-risk groups and shows how distinct vaccine properties translate to public health outcomes. These findings may be used to prioritise target product profile elements for second-generation childhood malaria vaccines.
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Affiliation(s)
- Alexandra B. Hogan
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Imperial College London, School of Public Health, St Mary’s Campus, Norfolk Place, London, W2 1PG UK
| | - Peter Winskill
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Imperial College London, School of Public Health, St Mary’s Campus, Norfolk Place, London, W2 1PG UK
| | - Robert Verity
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Imperial College London, School of Public Health, St Mary’s Campus, Norfolk Place, London, W2 1PG UK
| | - Jamie T. Griffin
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Imperial College London, School of Public Health, St Mary’s Campus, Norfolk Place, London, W2 1PG UK
- School of Mathematical Sciences, Queen Mary University London, Mile End Road, London, E1 4NS UK
| | - Azra C. Ghani
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis, Imperial College London, School of Public Health, St Mary’s Campus, Norfolk Place, London, W2 1PG UK
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41
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Gallay J, Mosha D, Lutahakana E, Mazuguni F, Zuakulu M, Decosterd LA, Genton B, Pothin E. Appropriateness of malaria diagnosis and treatment for fever episodes according to patient history and anti-malarial blood measurement: a cross-sectional survey from Tanzania. Malar J 2018; 17:209. [PMID: 29784001 PMCID: PMC5963060 DOI: 10.1186/s12936-018-2357-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 05/14/2018] [Indexed: 12/28/2022] Open
Abstract
Background Monitoring the impact of case management strategies at large scale is essential to evaluate the public health benefit they confer. The use of methodologies relying on objective and standardized endpoints, such as drug levels in the blood, should be encouraged. Population drug use, diagnosis and treatment appropriateness in case of fever according to patient history and anti-malarials blood concentration was evaluated. Methods A cross-sectional survey took place between May and August 2015 in three regions of Tanzania with different levels of malaria endemicity. Interviews were conducted and blood samples were collected by dried blood spots through household surveys for further anti-malarial measurements. Appropriate testing when individuals attended care was defined as a patient with history of fever being tested for malaria and appropriate treatment as (i) having anti-malarial in the blood if the test result was positive (ii) having anti-malarial in the blood if the person was not tested, and (iii) no anti-malarial in the blood when the test result was negative. Results Amongst 6391 participants included in the anti-malarial analysis, 20.8% (1330/6391) had anti-malarial drug detected in the blood. Only 28.0% (372/1330) of the individuals with anti-malarials in their blood reported the use of anti-malarials within the previous month. Amongst all participants, 16.0% (1021/6391) reported having had a fever in the previous 2 weeks and 37.5% of them (383/1021) had detectable levels of anti-malarials in the blood. Of the individuals who sought care in health facilities, 69.4% (172/248) were tested and 52.0% (129/248) appropriately treated. When other providers were sought, 6% (23/382) of the persons were appropriately tested and 44.2% (169/382) appropriately treated. Overall, the proportion of individuals treated was larger than that being tested [47.3% (298/630) treated, 31.0% (195/630) tested]. Conclusion This study showed high prevalence of circulating anti-malarial drug in the sampled population. Efforts should be made to increase rapid diagnostic tests use at all levels of health care and improve compliance to test result in order to target febrile patients that are sick with malaria and reduce drug pressure. Objective drug measurements collected at community level represent a reliable tool to evaluate overall impact of case management strategies on population drug pressure.
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Affiliation(s)
- Joanna Gallay
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box 4002, Basel, Switzerland. .,University of Basel, Basel, Switzerland. .,Service and Laboratory of Clinical Pharmacology, University Hospital, Lausanne, Switzerland.
| | | | | | | | | | | | - Blaise Genton
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box 4002, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Division of Infectious Diseases and Department of Community Health, University Hospital, Lausanne, Switzerland
| | - Emilie Pothin
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, P.O. Box 4002, Basel, Switzerland.,University of Basel, Basel, Switzerland
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Eikenberry SE, Gumel AB. Mathematical modeling of climate change and malaria transmission dynamics: a historical review. J Math Biol 2018; 77:857-933. [PMID: 29691632 DOI: 10.1007/s00285-018-1229-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 03/16/2018] [Indexed: 12/24/2022]
Abstract
Malaria, one of the greatest historical killers of mankind, continues to claim around half a million lives annually, with almost all deaths occurring in children under the age of five living in tropical Africa. The range of this disease is limited by climate to the warmer regions of the globe, and so anthropogenic global warming (and climate change more broadly) now threatens to alter the geographic area for potential malaria transmission, as both the Plasmodium malaria parasite and Anopheles mosquito vector have highly temperature-dependent lifecycles, while the aquatic immature Anopheles habitats are also strongly dependent upon rainfall and local hydrodynamics. A wide variety of process-based (or mechanistic) mathematical models have thus been proposed for the complex, highly nonlinear weather-driven Anopheles lifecycle and malaria transmission dynamics, but have reached somewhat disparate conclusions as to optimum temperatures for transmission, and the possible effect of increasing temperatures upon (potential) malaria distribution, with some projecting a large increase in the area at risk for malaria, but others predicting primarily a shift in the disease's geographic range. More generally, both global and local environmental changes drove the initial emergence of P. falciparum as a major human pathogen in tropical Africa some 10,000 years ago, and the disease has a long and deep history through the present. It is the goal of this paper to review major aspects of malaria biology, methods for formalizing these into mathematical forms, uncertainties and controversies in proper modeling methodology, and to provide a timeline of some major modeling efforts from the classical works of Sir Ronald Ross and George Macdonald through recent climate-focused modeling studies. Finally, we attempt to place such mathematical work within a broader historical context for the "million-murdering Death" of malaria.
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Affiliation(s)
- Steffen E Eikenberry
- Global Security Initiative, Arizona State University, Tempe, AZ, USA. .,School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, USA.
| | - Abba B Gumel
- School of Mathematical and Statistical Sciences, Arizona State University, Tempe, AZ, USA
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43
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Children with cerebral malaria or severe malarial anaemia lack immunity to distinct variant surface antigen subsets. Sci Rep 2018; 8:6281. [PMID: 29674705 PMCID: PMC5908851 DOI: 10.1038/s41598-018-24462-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/28/2018] [Indexed: 01/08/2023] Open
Abstract
Variant surface antigens (VSAs) play a critical role in severe malaria pathogenesis. Defining gaps, or “lacunae”, in immunity to these Plasmodium falciparum antigens in children with severe malaria would improve our understanding of vulnerability to severe malaria and how protective immunity develops. Using a protein microarray with 179 antigen variants from three VSA families as well as more than 300 variants of three other blood stage P. falciparum antigens, reactivity was measured in sera from Malian children with cerebral malaria or severe malarial anaemia and age-matched controls. Sera from children with severe malaria recognized fewer extracellular PfEMP1 fragments and were less reactive to specific fragments compared to controls. Following recovery from severe malaria, convalescent sera had increased reactivity to certain non-CD36 binding PfEMP1s, but not other malaria antigens. Sera from children with severe malarial anaemia reacted to fewer VSAs than did sera from children with cerebral malaria, and both of these groups had lacunae in their seroreactivity profiles in common with children who had both cerebral malaria and severe malarial anaemia. This microarray-based approach may identify a subset of VSAs that could inform the development of a vaccine to prevent severe disease or a diagnostic test to predict at-risk children.
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Parmar R, Patel H, Yadav N, Parikh R, Patel K, Mohankrishnan A, Bhurani V, Joshi U, Dalai SK. Infectious Sporozoites of Plasmodium berghei Effectively Activate Liver CD8α + Dendritic Cells. Front Immunol 2018; 9:192. [PMID: 29472929 PMCID: PMC5809440 DOI: 10.3389/fimmu.2018.00192] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 01/23/2018] [Indexed: 11/13/2022] Open
Abstract
Immunization with radiation-attenuated sporozoites (RAS) shown to confer complete sterile protection against Plasmodia liver-stage (LS) infection that lasts about 6 to 9 months in mice. We have found that the intermittent infectious sporozoite challenge to immune mice following RAS vaccination extends the longevity of sterile protection by maintaining CD8+ T cell memory responses to LS infection. It is reported that CD8α+ dendritic cells (DCs) are involved in the induction of LS-specific CD8+ T cells following RAS or genetically attenuated parasite (GAP) vaccination. In this study, we demonstrate that CD8α+ DCs respond differently to infectious sporozoite or RAS inoculation. The higher accumulation and activation of CD8α+ DCs was seen in the liver in response to infectious sporozoite 72 h postinoculation and found to be associated with higher expression of chemokines (CCL-20 and CCL-21) and type I interferon response via toll-like receptor signaling in liver. Moreover, the infectious sporozoites were found to induce qualitative changes in terms of the increased MHCII expression as well as costimulatory molecules including CD40 on the CD8α+ DCs compared to RAS inoculation. We have also found that infectious sporozoite challenge increased CD40L-expressing CD4+ T cells, which could help CD8+ T cells in the liver through "licensing" of the antigen-presenting cells. Our results suggest that infectious sporozoite challenge to prior RAS immunized mice modulates the CD8α+ DCs, which might be shaping the fate of memory CD8+ T cells against Plasmodium LS infection.
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Affiliation(s)
- Rajesh Parmar
- Institute of Science, Nirma University, Ahmedabad, India
| | - Hardik Patel
- Institute of Science, Nirma University, Ahmedabad, India
| | - Naveen Yadav
- Institute of Science, Nirma University, Ahmedabad, India
| | - Ritika Parikh
- Institute of Science, Nirma University, Ahmedabad, India
| | - Khyati Patel
- Institute of Science, Nirma University, Ahmedabad, India
| | | | | | - Urja Joshi
- Institute of Science, Nirma University, Ahmedabad, India
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Abstract
The incidence of malaria in sub-Saharan Africa is falling and in many countries on the continent the pattern of malaria infection within the country is becoming more heterogeneous. National malaria control programmes need to take this into account and the 'one size fits all' approach to malaria control may no longer be appropriate, with individual approaches being needed in different parts of a country. This applies particularly to decisions on the introduction of new control tools. Recent experience with Seasonal Malaria Chemoprevention and with the RTS,S/AS01 malaria vaccine provides examples of interventions which need to be deployed on a restricted rather than a national basis, taking account of differences in climate and the intensity of malaria infection between regions within a country. Designing, implementing and monitoring more complex national malaria control programmes will require staff skilled in many disciplines, and substantial funding will be needed to sustain these more complex control programmes, even though the burden of the disease is falling.
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Amoah LE, Acquah FK, Ayanful-Torgby R, Oppong A, Abankwa J, Obboh EK, Singh SK, Theisen M. Dynamics of anti-MSP3 and Pfs230 antibody responses and multiplicity of infection in asymptomatic children from southern Ghana. Parasit Vectors 2018; 11:13. [PMID: 29304870 PMCID: PMC5755320 DOI: 10.1186/s13071-017-2607-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 12/25/2017] [Indexed: 11/25/2022] Open
Abstract
Background During a Plasmodium infection, exposure of human host immune cells to both the asexual and the sexual stages of the parasite elicit immune responses. These responses may be protective and prevent the development of high parasitaemia and its associated clinical symptoms, or block the transmission of malaria to an uninfected person. This study aimed at examining the dynamics of naturally acquired immune responses against the asexual and sexual forms of Plasmodium falciparum as well as assessing differences in the multiplicity of infection (MOI) in asymptomatic Ghanaian children living in two communities with varying malaria transmission intensities. Methods School children aged between 6 and 12 years were recruited from Obom, a high malaria prevalence setting and Abura, a low malaria prevalence setting and enrolled in monthly multiple cross sectional surveys between February and May 2015. Filter paper blood blots (DBS) as well as thick and thin blood smears were made from finger-pricked blood at each visit. Plasmodium falciparum parasite prevalence was determined by microscopy and PCR. Serum eluted from the DBS were used to assess anti-Pfs230 (sexual stage) and anti-MSP3 (asexual stage) antibody levels using indirect ELISA and DNA extracted from the DBS used to assess MOI. Results Malaria parasite point prevalence and MOI throughout the study was higher in Obom than Abura. The trend of parasite prevalence estimated by microscopy was similar to that determined by PCR in Obom but not in Abura. The trend of MSP3 antibody seroprevalence followed that of PCR-estimated parasite prevalence in Obom, while in Abura the trend of Pfs230 antibody seroprevalence followed that of PCR-estimated parasite prevalence. Conclusions Microscopy can more accurately predict changes in parasite prevalence in high transmission settings than low transmission settings. In high transmission settings, P. falciparum parasite prevalence can predict antibody seroprevalence to MSP3, whilst in low transmission settings, seroprevalence against Pfs230 may be a useful predictor of parasite prevalence. Electronic supplementary material The online version of this article (10.1186/s13071-017-2607-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Linda E Amoah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
| | - Festus K Acquah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Ruth Ayanful-Torgby
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Akua Oppong
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Joana Abankwa
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Evans K Obboh
- School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Susheel K Singh
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Michael Theisen
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
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Abstract
This paper summarises key advances and priorities since the 2011 presentation of the Malaria Eradication Research Agenda (malERA), with a focus on the combinations of intervention tools and strategies for elimination and their evaluation using modelling approaches. With an increasing number of countries embarking on malaria elimination programmes, national and local decisions to select combinations of tools and deployment strategies directed at malaria elimination must address rapidly changing transmission patterns across diverse geographic areas. However, not all of these approaches can be systematically evaluated in the field. Thus, there is potential for modelling to investigate appropriate 'packages' of combined interventions that include various forms of vector control, case management, surveillance, and population-based approaches for different settings, particularly at lower transmission levels. Modelling can help prioritise which intervention packages should be tested in field studies, suggest which intervention package should be used at a particular level or stratum of transmission intensity, estimate the risk of resurgence when scaling down specific interventions after local transmission is interrupted, and evaluate the risk and impact of parasite drug resistance and vector insecticide resistance. However, modelling intervention package deployment against a heterogeneous transmission background is a challenge. Further validation of malaria models should be pursued through an iterative process, whereby field data collected with the deployment of intervention packages is used to refine models and make them progressively more relevant for assessing and predicting elimination outcomes.
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Winskill P, Slater HC, Griffin JT, Ghani AC, Walker PGT. The US President's Malaria Initiative, Plasmodium falciparum transmission and mortality: A modelling study. PLoS Med 2017; 14:e1002448. [PMID: 29161259 PMCID: PMC5697814 DOI: 10.1371/journal.pmed.1002448] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 10/18/2017] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Although significant progress has been made in reducing malaria transmission globally in recent years, a large number of people remain at risk and hence the gains made are fragile. Funding lags well behind amounts needed to protect all those at risk and ongoing contributions from major donors, such as the President's Malaria Initiative (PMI), are vital to maintain progress and pursue further reductions in burden. We use a mathematical modelling approach to estimate the impact of PMI investments to date in reducing malaria burden and to explore the potential negative impact on malaria burden should a proposed 44% reduction in PMI funding occur. METHODS AND FINDINGS We combined an established mathematical model of Plasmodium falciparum transmission dynamics with epidemiological, intervention, and PMI-financing data to estimate the contribution PMI has made to malaria control via funding for long-lasting insecticide treated nets (LLINs), indoor residual spraying (IRS), and artemisinin combination therapies (ACTs). We estimate that PMI has prevented 185 million (95% CrI: 138 million, 230 million) malaria cases and saved 940,049 (95% CrI: 545,228, 1.4 million) lives since 2005. If funding is maintained, PMI-funded interventions are estimated to avert a further 162 million (95% CrI: 116 million, 194 million) cases, saving a further 692,589 (95% CrI: 392,694, 955,653) lives between 2017 and 2020. With an estimate of US$94 (95% CrI: US$51, US$166) per Disability Adjusted Life Year (DALY) averted, PMI-funded interventions are highly cost-effective. We also demonstrate the further impact of this investment by reducing caseloads on health systems. If a 44% reduction in PMI funding were to occur, we predict that this loss of direct aid could result in an additional 67 million (95% CrI: 49 million, 82 million) cases and 290,649 (95% CrI: 167,208, 395,263) deaths between 2017 and 2020. We have not modelled indirect impacts of PMI funding (such as health systems strengthening) in this analysis. CONCLUSIONS Our model estimates that PMI has played a significant role in reducing malaria cases and deaths since its inception. Reductions in funding to PMI could lead to large increases in the number of malaria cases and deaths, damaging global goals of malaria control and elimination.
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Affiliation(s)
- Peter Winskill
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Hannah C Slater
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Jamie T Griffin
- School of Mathematical Sciences, Queen Mary University of London, London, United Kingdom
| | - Azra C Ghani
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Patrick G T Walker
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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Tuikue Ndam N, Moussiliou A, Lavstsen T, Kamaliddin C, Jensen ATR, Mama A, Tahar R, Wang CW, Jespersen JS, Alao JM, Gamain B, Theander TG, Deloron P. Parasites Causing Cerebral Falciparum Malaria Bind Multiple Endothelial Receptors and Express EPCR and ICAM-1-Binding PfEMP1. J Infect Dis 2017; 215:1918-1925. [PMID: 28863469 DOI: 10.1093/infdis/jix230] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 05/10/2017] [Indexed: 11/12/2022] Open
Abstract
Background Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) mediates the binding and accumulation of infected erythrocytes (IE) to blood vessels and tissues. Specific interactions have been described between PfEMP1 and human endothelial proteins CD36, intercellular adhesion molecule-1 (ICAM-1), and endothelial protein C receptor (EPCR); however, cytoadhesion patterns typical for pediatric malaria syndromes and the associated PfEMP1 members are still undefined. Methods In a cohort of 94 hospitalized children with malaria, we characterized the binding properties of IE collected on admission, and var gene transcription using quantitative polymerase chain reaction. Results IE from patients with cerebral malaria were more likely to bind EPCR and ICAM-1 than IE from children with uncomplicated malaria (P = .007). The level of transcripts encoding CIDRα1.4 and CIDRα1.5 domain subclasses was higher in patients with severe disease (P < .05). IE populations exhibiting binding to all 3 receptors had higher levels of transcripts encoding PfEMP1 with CIDRα1.4 and Duffy binding-like (DBL)-β3 domains than parasites, which only bound CD36. Conclusions These results underpin the significance of EPCR binding in pediatric malaria patients that require hospital admission, and support the notion that complementary receptor interactions of EPCR binding PfEMP1with ICAM-1 amplifies development of severe malaria symptoms.
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Affiliation(s)
- Nicaise Tuikue Ndam
- UMR 216, Mère et enfant face aux infections tropicales, Institut de Recherche pour le développement, COMUE Sorbonne Paris Cité, Faculté de pharmacie, Laboratoire d'Excellence GR-Ex, DHU Risques et Grossesse, France
| | - Azizath Moussiliou
- UMR 216, Mère et enfant face aux infections tropicales, Institut de Recherche pour le développement, COMUE Sorbonne Paris Cité, Faculté de pharmacie, Laboratoire d'Excellence GR-Ex, DHU Risques et Grossesse, France
| | - Thomas Lavstsen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Denmark
| | - Claire Kamaliddin
- UMR 216, Mère et enfant face aux infections tropicales, Institut de Recherche pour le développement, COMUE Sorbonne Paris Cité, Faculté de pharmacie, Laboratoire d'Excellence GR-Ex, DHU Risques et Grossesse, France
| | - Anja T R Jensen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Denmark
| | - Atikatou Mama
- Centre d'Etude et de Recherche sur le paludisme associé à la Grossesse et à l'Enfance, Université d'Abomey-Calavi
| | - Rachida Tahar
- UMR 216, Mère et enfant face aux infections tropicales, Institut de Recherche pour le développement, COMUE Sorbonne Paris Cité, Faculté de pharmacie, Laboratoire d'Excellence GR-Ex, DHU Risques et Grossesse, France
| | - Christian W Wang
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Denmark
| | - Jakob S Jespersen
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Denmark
| | - Jules M Alao
- Département de pédiatrie, Hôpital Mère-enfant de la lagune, Cotonou, Bénin
| | - Benoit Gamain
- Université Sorbonne Paris Cité, Université Paris Diderot, Inserm, INTS, Unité Biologie Intégrée du Globule Rouge, Laboratoire d'Excellence GR-Ex, France
| | - Thor G Theander
- Centre for Medical Parasitology, Department of Immunology and Microbiology, Faculty of Health and Medical Sciences, University of Copenhagen and Department of Infectious Diseases, Copenhagen University Hospital, Denmark
| | - Philippe Deloron
- UMR 216, Mère et enfant face aux infections tropicales, Institut de Recherche pour le développement, COMUE Sorbonne Paris Cité, Faculté de pharmacie, Laboratoire d'Excellence GR-Ex, DHU Risques et Grossesse, France
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50
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Watson OJ, Slater HC, Verity R, Parr JB, Mwandagalirwa MK, Tshefu A, Meshnick SR, Ghani AC. Modelling the drivers of the spread of Plasmodium falciparum hrp2 gene deletions in sub-Saharan Africa. eLife 2017; 6:25008. [PMID: 28837020 PMCID: PMC5602420 DOI: 10.7554/elife.25008] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 08/21/2017] [Indexed: 11/13/2022] Open
Abstract
Rapid diagnostic tests (RDTs) have transformed malaria diagnosis. The most prevalent P. falciparum RDTs detect histidine-rich protein 2 (PfHRP2). However, pfhrp2 gene deletions yielding false-negative RDTs, first reported in South America in 2010, have been confirmed in Africa and Asia. We developed a mathematical model to explore the potential for RDT-led diagnosis to drive selection of pfhrp2-deleted parasites. Low malaria prevalence and high frequencies of people seeking treatment resulted in the greatest selection pressure. Calibrating our model against confirmed pfhrp2-deletions in the Democratic Republic of Congo, we estimate a starting frequency of 6% pfhrp2-deletion prior to RDT introduction. Furthermore, the patterns observed necessitate a degree of selection driven by the introduction of PfHRP2-based RDT-guided treatment. Combining this with parasite prevalence and treatment coverage estimates, we map the model-predicted spread of pfhrp2-deletion, and identify the geographic regions in which surveillance for pfhrp2-deletion should be prioritised.
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Affiliation(s)
- Oliver J Watson
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Hannah C Slater
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Robert Verity
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Jonathan B Parr
- Division of Infectious Diseases, University of North Carolina, Chapel Hill, United States
| | - Melchior K Mwandagalirwa
- Division of Infectious Diseases, University of North Carolina, Chapel Hill, United States.,Ecole de Santé Publique, Faculté de Medecine, Université de Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Antoinette Tshefu
- Ecole de Santé Publique, Faculté de Medecine, Université de Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Steven R Meshnick
- Division of Infectious Diseases, University of North Carolina, Chapel Hill, United States
| | - Azra C Ghani
- Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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