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Otambo WO, Omondi CJ, Ochwedo KO, Onyango PO, Atieli H, Lee MC, Wang C, Zhou G, Githeko AK, Githure J, Ouma C, Yan G, Kazura J. Risk associations of submicroscopic malaria infection in lakeshore, plateau and highland areas of Kisumu County in western Kenya. PLoS One 2022; 17:e0268463. [PMID: 35576208 PMCID: PMC9109926 DOI: 10.1371/journal.pone.0268463] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/29/2022] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Persons with submicroscopic malaria infection are a major reservoir of gametocytes that sustain malaria transmission in sub-Saharan Africa. Despite recent decreases in the national malaria burden in Kenya due to vector control interventions, malaria transmission continues to be high in western regions of the country bordering Lake Victoria. The objective of this study was to advance knowledge of the topographical, demographic and behavioral risk factors associated with submicroscopic malaria infection in the Lake Victoria basin in Kisumu County. METHODS Cross-sectional community surveys for malaria infection were undertaken in three eco-epidemiologically distinct zones in Nyakach sub-County, Kisumu. Adjacent regions were topologically characterized as lakeshore, hillside and highland plateau. Surveys were conducted during the 2019 and 2020 wet and dry seasons. Finger prick blood smears and dry blood spots (DBS) on filter paper were collected from 1,777 healthy volunteers for microscopic inspection and real time-PCR (RT-PCR) diagnosis of Plasmodium infection. Persons who were PCR positive but blood smear negative were considered to harbor submicroscopic infections. Topographical, demographic and behavioral risk factors were correlated with community prevalence of submicroscopic infections. RESULTS Out of a total of 1,777 blood samples collected, 14.2% (253/1,777) were diagnosed as submicroscopic infections. Blood smear microscopy and RT-PCR, respectively, detected 3.7% (66/1,777) and 18% (319/1,777) infections. Blood smears results were exclusively positive for P. falciparum, whereas RT-PCR also detected P. malariae and P. ovale mono- and co-infections. Submicroscopic infection prevalence was associated with topographical variation (χ2 = 39.344, df = 2, p<0.0001). The highest prevalence was observed in the lakeshore zone (20.6%, n = 622) followed by the hillside (13.6%, n = 595) and highland plateau zones (7.9%, n = 560). Infection prevalence varied significantly according to season (χ2 = 17.374, df = 3, p<0.0001). The highest prevalence was observed in residents of the lakeshore zone in the 2019 dry season (29.9%, n = 167) and 2020 and 2019 rainy seasons (21.5%, n = 144 and 18.1%, n = 155, respectively). In both the rainy and dry seasons the likelihood of submicroscopic infection was higher in the lakeshore (AOR: 2.71, 95% CI = 1.85-3.95; p<0.0001) and hillside (AOR: 1.74, 95% CI = 1.17-2.61, p = 0.007) than in the highland plateau zones. Residence in the lakeshore zone (p<0.0001), male sex (p = 0.025), school age (p = 0.002), and living in mud houses (p = 0.044) increased the risk of submicroscopic malaria infection. Bed net use (p = 0.112) and occupation (p = 0.116) were not associated with submicroscopic infection prevalence. CONCLUSION Topographic features of the local landscape and seasonality are major correlates of submicroscopic malaria infection in the Lake Victoria area of western Kenya. Diagnostic tests more sensitive than blood smear microscopy will allow for monitoring and targeting geographic sites where additional vector interventions are needed to reduce malaria transmission.
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Affiliation(s)
- Wilfred Ouma Otambo
- Department of Zoology, Maseno University, Kisumu, Kenya
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Collince J. Omondi
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Kevin O. Ochwedo
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | | | - Harrysone Atieli
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Ming-Chieh Lee
- Department of Population Health and Disease Prevention, University of California, Irvine, CA, United States of America
| | - Chloe Wang
- Department of Population Health and Disease Prevention, University of California, Irvine, CA, United States of America
| | - Guofa Zhou
- Department of Population Health and Disease Prevention, University of California, Irvine, CA, United States of America
| | - Andrew K. Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - John Githure
- International Centre of Excellence for Malaria Research, Tom Mboya University College of Maseno University, Homa Bay, Kenya
| | - Collins Ouma
- Department of Biomedical Sciences and Technology, Maseno University, Kisumu, Kenya
| | - Guiyun Yan
- Department of Population Health and Disease Prevention, University of California, Irvine, CA, United States of America
| | - James Kazura
- Centre for Global Health & Diseases, Case Western University Reserve, Cleveland, Ohio, United States of America
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Hamlet A, Dengela D, Tongren JE, Tadesse FG, Bousema T, Sinka M, Seyoum A, Irish SR, Armistead JS, Churcher T. The potential impact of Anopheles stephensi establishment on the transmission of Plasmodium falciparum in Ethiopia and prospective control measures. BMC Med 2022; 20:135. [PMID: 35440085 PMCID: PMC9020030 DOI: 10.1186/s12916-022-02324-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 03/07/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Sub-Saharan Africa has seen substantial reductions in cases and deaths due to malaria over the past two decades. While this reduction is primarily due to an increasing expansion of interventions, urbanisation has played its part as urban areas typically experience substantially less malaria transmission than rural areas. However, this may be partially lost with the invasion and establishment of Anopheles stephensi. A. stephensi, the primary urban malaria vector in Asia, was first detected in Africa in 2012 in Djibouti and was subsequently identified in Ethiopia in 2016, and later in Sudan and Somalia. In Djibouti, malaria cases have increased 30-fold from 2012 to 2019 though the impact in the wider region remains unclear. METHODS Here, we have adapted an existing model of mechanistic malaria transmission to estimate the increase in vector density required to explain the trends in malaria cases seen in Djibouti. To account for the observed plasticity in An. stephensi behaviour, and the unknowns of how it will establish in a novel environment, we sample behavioural parameters in order to account for a wide range of uncertainty. This quantification is then applied to Ethiopia, considering temperature-dependent extrinsic incubation periods, pre-existing vector-control interventions and Plasmodium falciparum prevalence in order to assess the potential impact of An. stephensi establishment on P. falciparum transmission. Following this, we estimate the potential impact of scaling up ITN (insecticide-treated nets)/IRS (indoor residual spraying) and implementing piperonyl butoxide (PBO) ITNs and larval source management, as well as their economic costs. RESULTS We estimate that annual P. falciparum malaria cases could increase by 50% (95% CI 14-90) if no additional interventions are implemented. The implementation of sufficient control measures to reduce malaria transmission to pre-stephensi levels will cost hundreds of millions of USD. CONCLUSIONS Substantial heterogeneity across the country is predicted and large increases in vector control interventions could be needed to prevent a major public health emergency.
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Affiliation(s)
- Arran Hamlet
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK.
- The Abdul Latif Jameel Institute for Disease and Emergency Analytics, School of Public Health, Imperial College London, London, UK.
| | - Dereje Dengela
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - J Eric Tongren
- U.S. President's Malaria Initiative (PMI), Addis Ababa, Ethiopia
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Fitsum G Tadesse
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Marianne Sinka
- Department of Zoology, University of Oxford, Oxford, OX1 3SZ, UK
| | - Aklilu Seyoum
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Seth R Irish
- U.S. President's Malaria Initiative, Entomology Branch Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Jennifer S Armistead
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, D.C., USA
| | - Thomas Churcher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
- The Abdul Latif Jameel Institute for Disease and Emergency Analytics, School of Public Health, Imperial College London, London, UK
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Yaro JB, Tiono AB, Ouedraogo A, Lambert B, Ouedraogo ZA, Diarra A, Traore A, Lankouande M, Soulama I, Sanou A, Worrall E, Agboraw E, Sagnon N, Ranson H, Churcher TS, Lindsay SW, Wilson AL. Risk of Plasmodium falciparum infection in south-west Burkina Faso: potential impact of expanding eligibility for seasonal malaria chemoprevention. Sci Rep 2022; 12:1402. [PMID: 35082312 PMCID: PMC8791962 DOI: 10.1038/s41598-022-05056-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 12/10/2021] [Indexed: 11/10/2022] Open
Abstract
Burkina Faso has one of the highest malaria burdens in sub-Saharan Africa despite the mass deployment of insecticide-treated nets (ITNs) and use of seasonal malaria chemoprevention (SMC) in children aged up to 5 years. Identification of risk factors for Plasmodium falciparum infection in rural Burkina Faso could help to identify and target malaria control measures. A cross-sectional survey of 1,199 children and adults was conducted during the peak malaria transmission season in the Cascades Region of south-west Burkina Faso in 2017. Logistic regression was used to identify risk factors for microscopically confirmed P. falciparum infection. A malaria transmission dynamic model was used to determine the impact on malaria cases averted of administering SMC to children aged 5-15 year old. P. falciparum prevalence was 32.8% in the study population. Children aged 5 to < 10 years old were at 3.74 times the odds (95% CI = 2.68-5.22, P < 0.001) and children aged 10 to 15 years old at 3.14 times the odds (95% CI = 1.20-8.21, P = 0.02) of P. falciparum infection compared to children aged less than 5 years old. Administration of SMC to children aged up to 10 years is predicted to avert an additional 57 malaria cases per 1000 population per year (9.4% reduction) and administration to children aged up to 15 years would avert an additional 89 malaria cases per 1000 population per year (14.6% reduction) in the Cascades Region, assuming current coverage of pyrethroid-piperonyl butoxide ITNs. Malaria infections were high in all age strata, although highest in children aged 5 to 15 years, despite roll out of core malaria control interventions. Given the burden of infection in school-age children, extension of the eligibility criteria for SMC could help reduce the burden of malaria in Burkina Faso and other countries in the region.
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Affiliation(s)
- Jean Baptiste Yaro
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Department of Biosciences, Durham University, Durham, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Ben Lambert
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | - Z Amidou Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Amidou Diarra
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Adama Traore
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Malik Lankouande
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Institut de Recherche en Sciences de la Santé, Ouagadougou, Burkina Faso
| | - Antoine Sanou
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Institute of Biodiversity, Animal Health & Comparative Medicine, Glasgow University, Glasgow, UK
| | - Eve Worrall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Efundem Agboraw
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - N'Fale Sagnon
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
| | | | - Anne L Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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“Man Who Won the War”: Myth and Reality of Aldo Castellani’s Role in Preserving the Health of Troops During the Italo-Ethiopian War 1935–1936. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022. [DOI: 10.1007/5584_2022_737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Thomas A, Bakai TA, Atcha-Oubou T, Tchadjobo T, Bossard N, Rabilloud M, Voirin N. Seasonality of confirmed malaria cases from 2008 to 2017 in Togo: a time series analysis by health district and target group. BMC Infect Dis 2021; 21:1189. [PMID: 34836505 PMCID: PMC8620157 DOI: 10.1186/s12879-021-06893-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 11/17/2021] [Indexed: 11/10/2022] Open
Abstract
Background This study aimed to assess the seasonality of confirmed malaria cases in Togo and to provide new indicators of malaria seasonality to the National Malaria Control Programme (NMCP). Methods Aggregated data of confirmed malaria cases were collected monthly from 2008 to 2017 by the Togo’s NMCP and stratified by health district and according to three target groups: children < 5 years old, children ≥ 5 years old and adults, and pregnant women. Time series analysis was carried out for each target group and health district. Seasonal decomposition was used to assess the seasonality of confirmed malaria cases. Maximum and minimum seasonal indices, their corresponding months, and the ratio of maximum/minimum seasonal indices reflecting the importance of malaria transmission, were provided by health district and target group. Results From 2008 to 2017, 7,951,757 malaria cases were reported in Togo. Children < 5 years old, children ≥ 5 years old and adults, and pregnant women represented 37.1%, 57.7% and 5.2% of the confirmed malaria cases, respectively. The maximum seasonal indices were observed during or shortly after a rainy season and the minimum seasonal indices during the dry season between January and April in particular. In children < 5 years old, the ratio of maximum/minimum seasonal indices was higher in the north, suggesting a higher seasonal malaria transmission, than in the south of Togo. This is also observed in the other two groups but to a lesser extent. Conclusions This study contributes to a better understanding of malaria seasonality in Togo. The indicators of malaria seasonality could allow for more accurate forecasting in malaria interventions and supply planning throughout the year. Supplementary Information The online version contains supplementary material available at 10.1186/s12879-021-06893-z.
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Affiliation(s)
- Anne Thomas
- Université de Lyon, Lyon, France. .,Université Lyon 1, Villeurbanne, France. .,Service de Biostatistique et Bioinformatique, Pôle Santé Publique, Hospices Civils de Lyon, Lyon, France. .,Équipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Évolutive, CNRS, UMR 5558, Villeurbanne, France. .,Epidemiology and Modelling of Infectious Diseases (EPIMOD), Lent, France.
| | - Tchaa A Bakai
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,Service de Biostatistique et Bioinformatique, Pôle Santé Publique, Hospices Civils de Lyon, Lyon, France.,Équipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Évolutive, CNRS, UMR 5558, Villeurbanne, France.,Epidemiology and Modelling of Infectious Diseases (EPIMOD), Lent, France.,Programme National de Lutte contre le Paludisme (PNLP), Lomé, Togo
| | | | | | - Nadine Bossard
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,Service de Biostatistique et Bioinformatique, Pôle Santé Publique, Hospices Civils de Lyon, Lyon, France.,Équipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Évolutive, CNRS, UMR 5558, Villeurbanne, France
| | - Muriel Rabilloud
- Université de Lyon, Lyon, France.,Université Lyon 1, Villeurbanne, France.,Service de Biostatistique et Bioinformatique, Pôle Santé Publique, Hospices Civils de Lyon, Lyon, France.,Équipe Biostatistique-Santé, Laboratoire de Biométrie et Biologie Évolutive, CNRS, UMR 5558, Villeurbanne, France
| | - Nicolas Voirin
- Epidemiology and Modelling of Infectious Diseases (EPIMOD), Lent, France
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Runge M, Mapua S, Nambunga I, Smith TA, Chitnis N, Okumu F, Pothin E. Evaluation of different deployment strategies for larviciding to control malaria: a simulation study. Malar J 2021; 20:324. [PMID: 34315473 PMCID: PMC8314573 DOI: 10.1186/s12936-021-03854-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 07/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Larviciding against malaria vectors in Africa has been limited to indoor residual spraying and insecticide-treated nets, but is increasingly being considered by some countries as a complementary strategy. However, despite progress towards improved larvicides and new tools for mapping or treating mosquito-breeding sites, little is known about the optimal deployment strategies for larviciding in different transmission and seasonality settings. METHODS A malaria transmission model, OpenMalaria, was used to simulate varying larviciding strategies and their impact on host-seeking mosquito densities, entomological inoculation rate (EIR) and malaria prevalence. Variations in coverage, duration, frequency, and timing of larviciding were simulated for three transmission intensities and four transmission seasonality profiles. Malaria transmission was assumed to follow rainfall with a lag of one month. Theoretical sub-Saharan African settings with Anopheles gambiae as the dominant vector were chosen to explore impact. Relative reduction compared to no larviciding was predicted for each indicator during the simulated larviciding period. RESULTS Larviciding immediately reduced the predicted host-seeking mosquito densities and EIRs to a maximum that approached or exceeded the simulated coverage. Reduction in prevalence was delayed by approximately one month. The relative reduction in prevalence was up to four times higher at low than high transmission. Reducing larviciding frequency (i.e., from every 5 to 10 days) resulted in substantial loss in effectiveness (54, 45 and 53% loss of impact for host-seeking mosquito densities, EIR and prevalence, respectively). In seasonal settings the most effective timing of larviciding was during or at the beginning of the rainy season and least impactful during the dry season, assuming larviciding deployment for four months. CONCLUSION The results highlight the critical role of deployment strategies on the impact of larviciding. Overall, larviciding would be more effective in settings with low and seasonal transmission, and at the beginning and during the peak densities of the target species populations. For maximum impact, implementers should consider the practical ranges of coverage, duration, frequency, and timing of larviciding in their respective contexts. More operational data and improved calibration would enable models to become a practical tool to support malaria control programmes in developing larviciding strategies that account for the diversity of contexts.
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Affiliation(s)
- Manuela Runge
- Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Salum Mapua
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Ismail Nambunga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Thomas A Smith
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Fredros Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Emilie Pothin
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Clinton Health Access Initiative, Boston, USA
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Hamlet A, Ramos DG, Gaythorpe KAM, Romano APM, Garske T, Ferguson NM. Seasonality of agricultural exposure as an important predictor of seasonal yellow fever spillover in Brazil. Nat Commun 2021; 12:3647. [PMID: 34131128 PMCID: PMC8206143 DOI: 10.1038/s41467-021-23926-y] [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: 12/12/2019] [Accepted: 05/24/2021] [Indexed: 01/04/2023] Open
Abstract
Yellow fever virus (YFV) is a zoonotic arbovirus affecting both humans and non-human primates (NHP's) in Africa and South America. Previous descriptions of YF's seasonality have relied purely on climatic explanations, despite the high proportion of cases occurring in people involved in agriculture. We use a series of random forest classification models to predict the monthly occurrence of YF in humans and NHP's across Brazil, by fitting four classes of covariates related to the seasonality of climate and agriculture (planting and harvesting), crop output and host demography. We find that models captured seasonal YF reporting in humans and NHPs when they considered seasonality of agriculture rather than climate, particularly for monthly aggregated reports. These findings illustrate the seasonality of exposure, through agriculture, as a component of zoonotic spillover. Additionally, by highlighting crop types and anthropogenic seasonality, these results could directly identify areas at highest risk of zoonotic spillover.
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Affiliation(s)
- Arran Hamlet
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics, School of Public Health, Imperial College London, London, UK.
| | | | - Katy A M Gaythorpe
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics, School of Public Health, Imperial College London, London, UK
| | | | - Tini Garske
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics, School of Public Health, Imperial College London, London, UK
| | - Neil M Ferguson
- MRC Centre for Global Infectious Disease Analysis; and the Abdul Latif Jameel Institute for Disease and Emergency Analytics, School of Public Health, Imperial College London, London, UK
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8
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African genetic diversity and adaptation inform a precision medicine agenda. Nat Rev Genet 2021; 22:284-306. [PMID: 33432191 DOI: 10.1038/s41576-020-00306-8] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2020] [Indexed: 01/29/2023]
Abstract
The deep evolutionary history of African populations, since the emergence of modern humans more than 300,000 years ago, has resulted in high genetic diversity and considerable population structure. Selected genetic variants have increased in frequency due to environmental adaptation, but recent exposures to novel pathogens and changes in lifestyle render some of them with properties leading to present health liabilities. The unique discoverability potential from African genomic studies promises invaluable contributions to understanding the genomic and molecular basis of health and disease. Globally, African populations are understudied, and precision medicine approaches are largely based on data from European and Asian-ancestry populations, which limits the transferability of findings to the continent of Africa. Africa needs innovative precision medicine solutions based on African data that use knowledge and implementation strategies aligned to its climatic, cultural, economic and genomic diversity.
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Vekemans J, Schellenberg D, Benns S, O'Brien K, Alonso P. Meeting report: WHO consultation on malaria vaccine development, Geneva, 15-16 July 2019. Vaccine 2021; 39:2907-2916. [PMID: 33931251 DOI: 10.1016/j.vaccine.2021.03.093] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/26/2021] [Accepted: 03/29/2021] [Indexed: 01/25/2023]
Abstract
Considerable progress has been made in malaria control in the last two decades, but progress has stalled in the last few years. New tools are needed to achieve public health goals in malaria control and elimination. A first generation vaccine, RTS,S/AS01, is currently being evaluated as it undergoes pilot implementation through routine health systems in parts of three African countries. The development of this vaccine took over 30 years and has been full of uncertainties. Even now, important unknowns remain as to its future role in public health. Lessons need to be learnt for second generation and future vaccines, including how to facilitate early planning of investments, streamlining of development, regulatory and policy pathways. A number of candidate vaccines populate the current development pipeline, some of which have the potential to contribute to burden reduction if efficacy is confirmed in conditions of natural exposure, and if they are amenable to affordable supply and programmatic implementation. New, innovative technologies will be needed if future malaria vaccines are to overcome important scientific hurdles and induce durable, high level protection. WHO convened a stakeholder consultation on the status of malaria vaccine research and development to inform the recently reconstituted Malaria Vaccine Advisory Committee (MALVAC) which will assist WHO in updating its current guidance and recommendations about priorities and product preferences for malaria vaccines.
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Affiliation(s)
- Johan Vekemans
- World Health Organization, 20 Av Appia, 1211 Geneva 27, Switzerland
| | | | | | - Kate O'Brien
- World Health Organization, 20 Av Appia, 1211 Geneva 27, Switzerland
| | - Pedro Alonso
- World Health Organization, 20 Av Appia, 1211 Geneva 27, Switzerland
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10
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Diawara H, Walker P, Cairns M, Steinhardt LC, Diawara F, Kamate B, Duval L, Sicuri E, Sagara I, Sadou A, Mihigo J, Eckert E, Dicko A, Conteh L. Cost-effectiveness of district-wide seasonal malaria chemoprevention when implemented through routine malaria control programme in Kita, Mali using fixed point distribution. Malar J 2021; 20:128. [PMID: 33663488 PMCID: PMC7934250 DOI: 10.1186/s12936-021-03653-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 02/16/2021] [Indexed: 11/10/2022] Open
Abstract
Background Seasonal malaria chemoprevention (SMC) is a strategy for malaria control recommended by the World Health Organization (WHO) since 2012 for Sahelian countries. The Mali National Malaria Control Programme adopted a plan for pilot implementation and nationwide scale-up by 2016. Given that SMC is a relatively new approach, there is an urgent need to assess the costs and cost effectiveness of SMC when implemented through the routine health system to inform decisions on resource allocation. Methods Cost data were collected from pilot implementation of SMC in Kita district, which targeted 77,497 children aged 3–59 months. Starting in August 2014, SMC was delivered by fixed point distribution in villages with the first dose observed each month. Treatment consisted of sulfadoxine-pyrimethamine and amodiaquine once a month for four consecutive months, or rounds. Economic and financial costs were collected from the provider perspective using an ingredients approach. Effectiveness estimates were based upon a published mathematical transmission model calibrated to local epidemiology, rainfall patterns and scale-up of interventions. Incremental cost effectiveness ratios were calculated for the cost per malaria episode averted, cost per disability adjusted life years (DALYs) averted, and cost per death averted. Results The total economic cost of the intervention in the district of Kita was US $357,494. Drug costs and personnel costs accounted for 34% and 31%, respectively. Incentives (payment other than salary for efforts beyond routine activities) accounted for 25% of total implementation costs. Average financial and economic unit costs per child per round were US $0.73 and US $0.86, respectively; total annual financial and economic costs per child receiving SMC were US $2.92 and US $3.43, respectively. Accounting for coverage, the economic cost per child fully adherent (receiving all four rounds) was US $6.38 and US $4.69, if weighted highly adherent, (receiving 3 or 4 rounds of SMC). When costs were combined with modelled effects, the economic cost per malaria episode averted in children was US $4.26 (uncertainty bound 2.83–7.17), US $144 (135–153) per DALY averted and US $ 14,503 (13,604–15,402) per death averted. Conclusions When implemented at fixed point distribution through the routine health system in Mali, SMC was highly cost-effective. As in previous SMC implementation studies, financial incentives were a large cost component.
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Affiliation(s)
- Halimatou Diawara
- Malaria Research & Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, P.O Box 1805, Bamako, Mali.
| | - Patrick Walker
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Matt Cairns
- London School of Hygiene & Tropical Medicine, London, UK
| | - Laura C Steinhardt
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop H24-3, Atlanta, GA, 30329, USA
| | - Fatou Diawara
- Malaria Research & Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, P.O Box 1805, Bamako, Mali
| | - Beh Kamate
- Maternal and Child Survival Program, Save the Children, Bamako, Mali
| | - Laeticia Duval
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Elisa Sicuri
- Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Issaka Sagara
- Malaria Research & Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, P.O Box 1805, Bamako, Mali
| | - Aboubacar Sadou
- President's Malaria Initiative, US Agency for International Development, Kinshasa, Democratic Republic of the Congo
| | - Jules Mihigo
- President's Malaria Initiative, US Agency for International Development, Bamako, Mali
| | - Erin Eckert
- President's Malaria Initiative, USAID Bureau for Global Health, Office of Health, Infectious Diseases, and Nutrition, 2100 Crystal Drive, Arlington, VA, 22202, USA
| | - Alassane Dicko
- Malaria Research & Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, P.O Box 1805, Bamako, Mali
| | - Lesong Conteh
- Department of Health Policy, London School of Economics and Political Science, Houghton Street, London, WC2A 2AE, UK
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11
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Watson OJ, Okell LC, Hellewell J, Slater HC, Unwin HJT, Omedo I, Bejon P, Snow RW, Noor AM, Rockett K, Hubbart C, Nankabirwa JI, Greenhouse B, Chang HH, Ghani AC, Verity R. Evaluating the Performance of Malaria Genetics for Inferring Changes in Transmission Intensity Using Transmission Modeling. Mol Biol Evol 2021; 38:274-289. [PMID: 32898225 PMCID: PMC7783189 DOI: 10.1093/molbev/msaa225] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Substantial progress has been made globally to control malaria, however there is a growing need for innovative new tools to ensure continued progress. One approach is to harness genetic sequencing and accompanying methodological approaches as have been used in the control of other infectious diseases. However, to utilize these methodologies for malaria, we first need to extend the methods to capture the complex interactions between parasites, human and vector hosts, and environment, which all impact the level of genetic diversity and relatedness of malaria parasites. We develop an individual-based transmission model to simulate malaria parasite genetics parameterized using estimated relationships between complexity of infection and age from five regions in Uganda and Kenya. We predict that cotransmission and superinfection contribute equally to within-host parasite genetic diversity at 11.5% PCR prevalence, above which superinfections dominate. Finally, we characterize the predictive power of six metrics of parasite genetics for detecting changes in transmission intensity, before grouping them in an ensemble statistical model. The model predicted malaria prevalence with a mean absolute error of 0.055. Different assumptions about the availability of sample metadata were considered, with the most accurate predictions of malaria prevalence made when the clinical status and age of sampled individuals is known. Parasite genetics may provide a novel surveillance tool for estimating the prevalence of malaria in areas in which prevalence surveys are not feasible. However, the findings presented here reinforce the need for patient metadata to be recorded and made available within all future attempts to use parasite genetics for surveillance.
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Affiliation(s)
- Oliver J Watson
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Lucy C Okell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Joel Hellewell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Hannah C Slater
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - H Juliette T Unwin
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Irene Omedo
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Robert W Snow
- Population Health Unit, Kenya Medical Research Institute—Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Kirk Rockett
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Christina Hubbart
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Makerere University College of Health Sciences, Kampala, Uganda
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, CA
| | - Hsiao-Han Chang
- Center for Communicable Disease Dynamics, Harvard TH Chan School of Public Health, Boston, MA
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Robert Verity
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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12
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Addressing challenges in routine health data reporting in Burkina Faso through Bayesian spatiotemporal prediction of weekly clinical malaria incidence. Sci Rep 2020; 10:16568. [PMID: 33024162 PMCID: PMC7538437 DOI: 10.1038/s41598-020-73601-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 09/07/2020] [Indexed: 11/15/2022] Open
Abstract
Sub-Saharan African (SSA) countries’ health systems are often vulnerable to unplanned situations that can hinder their effectiveness in terms of data completeness and disease control. For instance, in Burkina Faso following a workers' strike, comprehensive data on several diseases were unavailable for a long period in 2019. Weather, seasonal-malaria-chemoprevention (SMC), free healthcare, and other contextual data, which are purported to influence malarial disease, provide opportunities to fit models to describe the clinical malaria data and predict the disease spread. Bayesian spatiotemporal modeling was applied to weekly malaria surveillance data from Burkina Faso (2011–2018) while considering the effects of weather, health programs and contextual factors. Then, a prediction was used to deal with weekly missing data for the entire year of 2019, and SMC and free healthcare effects were quantified. Our proposed model accurately predicted weekly clinical malaria incidence (correlation coefficient, r = 0.90). The distribution of clinical malaria incidence was heterogeneous across the country. Overall, national predicted clinical malaria incidence in 2019 (605 per 1000 [95% CrI: 360–990]) increased by 24.7% compared with the year 2015. SMC and the interaction between free healthcare and health facility attendance were associated with a reduction in clinical malaria incidence. Our modeling approach could be a useful tool for strengthening health systems’ resilience by addressing data completeness and could support SSA countries in developing appropriate targets and indicators to facilitate the subnational control effort.
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13
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Fowle K, Wells B, Day M, Kumar A, Bess C, Bingham B, Wayman A. The program and policy change framework: A new tool to measure research use in low- and middle-income countries. RESEARCH EVALUATION 2020. [DOI: 10.1093/reseval/rvaa017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Organizations that fund research to address global development challenges are increasingly interested in measuring the social and economic outcomes of research. However, traditional metrics for measuring research outputs are often insufficient for capturing the outcomes targeted by international assistance organizations. To address this, the Center for Development Research (CDR), part of the U.S. Global Development Lab at the United States Agency for International Development (USAID), has designed a new tool: the Program and Policy Change (PPC) framework for tracking and quantifying the influence of research on program and policy change in international development. The framework draws on existing conceptual frameworks of evidence uptake and the literature on policy change. This article describes the design of the PPC framework and presents the results of applying the framework to two USAID research programs. The benefits of the framework include applicability across research sectors, focus on evidence-informed policy at various levels of geographical influence, and inclusion of a numeric scoring system that enables quantification of outcomes.
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Affiliation(s)
- Karen Fowle
- The US Agency for International Development, 1300 Pennsylvania Ave NW, Washington, DC, 20004, USA
| | - Brent Wells
- The US Agency for International Development, 1300 Pennsylvania Ave NW, Washington, DC, 20004, USA
| | - Melissa Day
- The US Agency for International Development, 1300 Pennsylvania Ave NW, Washington, DC, 20004, USA
- Web of Science Group, Clarivate, 1900 Duke Street Ste 200, Alexandria, VA, 22314, USA
| | - Anjali Kumar
- The US Agency for International Development, 1300 Pennsylvania Ave NW, Washington, DC, 20004, USA
| | - Cameron Bess
- The US Agency for International Development, 1300 Pennsylvania Ave NW, Washington, DC, 20004, USA
| | - Brian Bingham
- The US Agency for International Development, 1300 Pennsylvania Ave NW, Washington, DC, 20004, USA
| | - Annica Wayman
- University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
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14
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Kigozi SP, Giorgi E, Mpimbaza A, Kigozi RN, Bousema T, Arinaitwe E, Nankabirwa JI, Sebuguzi CM, Kamya MR, Staedke SG, Dorsey G, Pullan RL. Practical Implications of a Relationship between Health Management Information System and Community Cohort-Based Malaria Incidence Rates. Am J Trop Med Hyg 2020; 103:404-414. [PMID: 32274990 DOI: 10.4269/ajtmh.19-0950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Global malaria burden is reducing with effective control interventions, and surveillance is vital to maintain progress. Health management information system (HMIS) data provide a powerful surveillance tool; however, its estimates of burden need to be better understood for effectiveness. We aimed to investigate the relationship between HMIS and cohort incidence rates and identify sources of bias in HMIS-based incidence. Malaria incidence was estimated using HMIS data from 15 health facilities in three subcounties in Uganda. This was compared with a gold standard of representative cohort studies conducted in children aged 0.5 to < 11 years, followed concurrently in these sites. Between October 2011 and September 2014, 153,079 children were captured through HMISs and 995 followed up through enhanced community cohorts in Walukuba, Kihihi, and Nagongera subcounties. Although HMISs substantially underestimated malaria incidence in all sites compared with data from the cohort studies, there was a strong linear relationship between these rates in the lower transmission settings (Walukuba and Kihihi), but not the lowest HMIS performance highest transmission site (Nagongera), with calendar year as a significant modifier. Although health facility accessibility, availability, and recording completeness were associated with HMIS incidence, they were not significantly associated with bias in estimates from any site. Health management information systems still require improvements; however, their strong predictive power of unbiased malaria burden when improved highlights the important role they could play as a cost-effective tool for monitoring trends and estimating impact of control interventions. This has important implications for malaria control in low-resource, high-burden countries.
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Affiliation(s)
- Simon P Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda.,Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Emanuele Giorgi
- CHICAS, Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Arthur Mpimbaza
- Child Health and Development Centre, Makerere University College of Health Sciences, Kampala, Uganda
| | - Ruth N Kigozi
- USAID's Malaria Action Program for Districts, Kampala, Uganda
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University, Nijmegen, Netherlands
| | | | - Joaniter I Nankabirwa
- School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Catherine M Sebuguzi
- National Malaria Control Division, Uganda Ministry of Health, Kampala, Uganda.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Moses R Kamya
- School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Sarah G Staedke
- Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, United Kingdom.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, San Francisco, California.,Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Rachel L Pullan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom
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15
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Ivermectin as a novel complementary malaria control tool to reduce incidence and prevalence: a modelling study. THE LANCET. INFECTIOUS DISEASES 2020; 20:498-508. [PMID: 31948767 DOI: 10.1016/s1473-3099(19)30633-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 09/30/2019] [Accepted: 10/21/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Ivermectin is a potential new vector control tool to reduce malaria transmission. Mosquitoes feeding on a bloodmeal containing ivermectin have a reduced lifespan, meaning they are less likely to live long enough to complete sporogony and become infectious. We aimed to estimate the effect of ivermectin on malaria transmission in various scenarios of use. METHODS We validated an existing population-level mathematical model of the effect of ivermectin mass drug administration (MDA) on the mosquito population and malaria transmission against two datasets: clinical data from a cluster- randomised trial done in Burkina Faso in 2015 wherein ivermectin was given to individuals taller than 90 cm and entomological data from a study of mosquito outcomes after ivermectin MDA for onchocerciasis or lymphatic filariasis in Burkina Faso, Senegal, and Liberia between 2008 and 2013. We extended the existing model to include a range of complementary malaria interventions (seasonal malaria chemoprevention and MDA with dihydroartemisinin-piperaquine) and to incorporate new data on higher doses of ivermectin with a longer mosquitocidal effect. We consider two ivermectin regimens: a single dose of 400 μg/kg (1 × 400 μg/kg) and three consecutive daily doses of 300 μg/kg per day (3 × 300 μg/kg). We simulated the effect of these two doses in a range of usage scenarios in different transmission settings (highly seasonal, seasonal, and perennial). We report percentage reductions in clinical incidence and slide prevalence. FINDINGS We estimate that MDA with ivermectin will reduce prevalence and incidence and is most effective in areas with highly seasonal transmission. In a highly seasonal moderate transmission setting, three rounds of ivermectin only MDA at 3 × 300 μg/kg (rounds spaced 1 month apart) and 70% coverage is predicted to reduce clinical incidence by 71% and prevalence by 34%. We predict that adding ivermectin MDA to seasonal malaria chemoprevention in this setting would reduce clinical incidence by an additional 77% in children younger than 5 years compared with seasonal malaria chemoprevention alone; adding ivermectin MDA to MDA with dihydroartemisinin-piperaquine in this setting would reduce incidence by an additional 75% and prevalence by an additional 64% (all ages) compared with MDA with dihydroartemisinin-piperaquine alone. INTERPRETATION Our modelling predictions suggest that ivermectin could be a valuable addition to the malaria control toolbox, both in areas with persistently high transmission where existing interventions are insufficient and in areas approaching elimination to prevent resurgence. FUNDING Imperial College Junior Research Fellowship.
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16
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Effect of Free Healthcare Policy for Children under Five Years Old on the Incidence of Reported Malaria Cases in Burkina Faso by Bayesian Modelling: "Not only the Ears but also the Head of the Hippopotamus". INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17020417. [PMID: 31936308 PMCID: PMC7014427 DOI: 10.3390/ijerph17020417] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 12/24/2019] [Accepted: 01/03/2020] [Indexed: 02/02/2023]
Abstract
Burkina Faso has recently implemented an additional strategy, the free healthcare policy, to further improve maternal and child health. This policy targets children under five who bear the brunt of the malaria scourge. The effects of the free-of-charge healthcare were previously assessed in women but not in children. The present study aims at filling this gap by assessing the effect of this policy in children under five with a focus on the induced spatial and temporal changes in malaria morbidity. We used a Bayesian spatiotemporal negative binomial model to investigate the space–time variation in malaria incidence in relation to the implementation of the policy. The analysis relied on malaria routine surveillance data extracted from the national health data repository and spanning the period from January 2013 to December 2018. The model was adjusted for meteorological and contextual confounders. We found that the number of presumed and confirmed malaria cases per 1000 children per month increased between 2013 and 2018. We further found that the implementation of the free healthcare policy was significantly associated with a two-fold increase in the number of tested and confirmed malaria cases compared with the period before the policy rollout. This effect was, however, heterogeneous across the health districts. We attributed the rise in malaria incidence following the policy rollout to an increased use of health services combined with an increased availability of rapid tests and a higher compliance to the “test and treat” policy. The observed heterogeneity in the policy effect was attributed to parallel control interventions, some of which were rolled out at different paces and scales. Our findings call for a sustained and reinforced effort to test all suspected cases so that, alongside an improved case treatment, the true picture of the malaria scourge in children under five emerges clearly (see the hippopotamus almost entirely).
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17
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Falade CO, Orimadegun AE, Michael OS, Dada-Adegbola HO, Ogunkunle OO, Badejo JA, Funwei RI, Ajayi IO, Jegede AS, Ojurongbe OD, Ssekitooleko J, Baba E, Hamade P, Webster J, Chandramohan D. Consequences of restricting antimalarial drugs to rapid diagnostic test-positive febrile children in south-west Nigeria. Trop Med Int Health 2019; 24:1291-1300. [PMID: 31465633 DOI: 10.1111/tmi.13304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To investigate the consequence of restricting antimalarial treatment to febrile children that test positive to a malaria rapid diagnostic test (MRDT) only in an area of intense malaria transmission. METHODS Febrile children aged 3-59 months were screened with an MRDT at health facilities in south-west Nigeria. MRDT-positive children received artesunate-amodiaquine (ASAQ), while MRDT-negative children were treated based on the clinical diagnosis of non-malaria febrile illness. The primary endpoint was the risk of developing microscopy-positive malaria within 28 days post-treatment. RESULTS 309 (60.5%) of 511 children were MRDT-positive while 202 (39.5%) were MRDT-negative at enrolment. 18.5% (50/275) of MRDT-positive children and 7.6% (14/184) of MRDT-negative children developed microscopy-positive malaria by day 28 post-treatment (ρ = 0.001). The risk of developing clinical malaria by day 28 post-treatment was higher among the MRDT-positive group than the MRDT-negative group (adjusted OR 2.74; 95% CI, 1.4, 5.4). A higher proportion of children who were MRDT-positive at enrolment were anaemic on day 28 compared with the MRDT-negative group (12.6% vs. 3.1%; ρ = 0.001). Children in the MRDT-negative group made more unscheduled visits because of febrile illness than those in MRDT-positive group (23.2% vs. 12.0%; ρ = 0.001). CONCLUSION Restricting ACT treatment to MRDT-positive febrile children only did not result in significant adverse outcomes. However, the risk of re-infection within 28 days was significantly higher among MRDT-positive children despite ASAQ treatment. A longer-acting ACT may be needed as the first-line drug of choice for treating uncomplicated malaria in high-transmission settings to prevent frequent re-infections.
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Affiliation(s)
- Catherine Olufunke Falade
- Department of Pharmacology & Therapeutics, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | | | - Obaro Stanley Michael
- Department of Pharmacology & Therapeutics, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | | | | | - Joseph Ayotunde Badejo
- Department of Pharmacology & Therapeutics, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Roland Ibenipere Funwei
- Department of Pharmacology & Therapeutics, College of Medicine, University of Ibadan, Ibadan, Nigeria.,Department of Pharmacy Technician Studies, Bayelsa State College of Health Technology, Otuogidi, Nigeria
| | - IkeOluwapo Oyeneye Ajayi
- Department of Epidemiology & Medical Statistics, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | - Ayodele Samuel Jegede
- Department of Sociology, Faculty of The Social Sciences, University of Ibadan, Ibadan, Nigeria
| | - Olusola Daniel Ojurongbe
- Department of Medical Microbiology and Parasitology, Ladoke Akintola University of Technology, Osogbo, Nigeria
| | | | - Ebenezer Baba
- Malaria Consortium Regional Office for Africa, Kampala, Uganda
| | | | - Jayne Webster
- London School of Tropical Medicine and Hygiene, London, UK
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18
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Watson OJ, Verity R, Ghani AC, Garske T, Cunningham J, Tshefu A, Mwandagalirwa MK, Meshnick SR, Parr JB, Slater HC. Impact of seasonal variations in Plasmodium falciparum malaria transmission on the surveillance of pfhrp2 gene deletions. eLife 2019; 8:40339. [PMID: 31045490 PMCID: PMC6533063 DOI: 10.7554/elife.40339] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 04/29/2019] [Indexed: 12/15/2022] Open
Abstract
Ten countries have reported pfhrp2/pfhrp3 gene deletions since the first observation of pfhrp2-deleted parasites in 2012. In a previous study (Watson et al., 2017), we characterised the drivers selecting for pfhrp2/3 deletions and mapped the regions in Africa with the greatest selection pressure. In February 2018, the World Health Organization issued guidance on investigating suspected false-negative rapid diagnostic tests (RDTs) due to pfhrp2/3 deletions. However, no guidance is provided regarding the timing of investigations. Failure to consider seasonal variation could cause premature decisions to switch to alternative RDTs. In response, we have extended our methods and predict that the prevalence of false-negative RDTs due to pfhrp2/3 deletions is highest when sampling from younger individuals during the beginning of the rainy season. We conclude by producing a map of the regions impacted by seasonal fluctuations in pfhrp2/3 deletions and a database identifying optimum sampling intervals to support malaria control programmes.
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Affiliation(s)
- Oliver John Watson
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Robert Verity
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Tini Garske
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Jane Cunningham
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Antoinette Tshefu
- School of Public Health, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Melchior K Mwandagalirwa
- School of Public Health, University of Kinshasa, Kinshasa, Democratic Republic of the Congo.,Department of Epidemiology, Gillings School for Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School for Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, United States.,Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Jonathan B Parr
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Hannah C Slater
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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19
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Abdullahi ST, Olagunju A, Soyinka JO, Bolarinwa RA, Olarewaju OJ, Bakare-Odunola MT, Owen A, Khoo S. Pharmacogenetics of artemether-lumefantrine influence on nevirapine disposition: Clinically significant drug-drug interaction? Br J Clin Pharmacol 2019; 85:540-550. [PMID: 30471138 DOI: 10.1111/bcp.13821] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 10/29/2018] [Accepted: 11/08/2018] [Indexed: 12/17/2022] Open
Abstract
AIMS In this study the influence of first-line antimalarial drug artemether-lumefantrine on the pharmacokinetics of the antiretroviral drug nevirapine was investigated in the context of selected single nucleotide polymorphisms (SNPs) in a cohort of adult HIV-infected Nigerian patients. METHODS This was a two-period, single sequence crossover study. In stage 1, 150 HIV-infected patients receiving nevirapine-based antiretroviral regimens were enrolled and genotyped for seven SNPs. Sparse pharmacokinetic sampling was conducted to identify SNPs independently associated with nevirapine plasma concentration. Patients were categorized as poor, intermediate and extensive metabolizers based on the numbers of alleles of significantly associated SNPs. Intensive sampling was conducted in selected patients from each group. In stage 2, patients received standard artemether-lumefantrine treatment with nevirapine, and intensive pharmacokinetic sampling was conducted on day 3. RESULTS No clinically significant changes were observed in key nevirapine pharmacokinetic parameters, the 90% confidence interval for the measured changes falling completely within the 0.80-1.25 no-effect boundaries. However, the number of patients with trough plasma nevirapine concentration below the 3400 ng ml-1 minimum effective concentration increased from 10% without artemether-lumefantrine (all extensive metabolizers) to 21% with artemether-lumefantrine (14% extensive, 4% intermediate, and 3% poor metabolizers). CONCLUSIONS This approach highlights additional increase in the already existing risk of suboptimal trough plasma concentration, especially in extensive metabolizers when nevirapine is co-administered with artemether-lumefantrine.
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Affiliation(s)
- Sa'ad T Abdullahi
- Department of Pharmaceutical Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.,Department of Pharmaceutical and Medicinal Chemistry, University of Ilorin, Ilorin, Nigeria
| | - Adeniyi Olagunju
- Department of Pharmaceutical Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria.,Department of Molecular and Clinical Pharmacology, University of Liverpool, 70 Pembroke Place, Liverpool, L69 3GF, UK
| | - Julius O Soyinka
- Department of Pharmaceutical Chemistry, Obafemi Awolowo University, Ile-Ife, Nigeria
| | - Rahman A Bolarinwa
- Department of Haematology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria
| | - Olusola J Olarewaju
- Department of Haematology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria
| | - Moji T Bakare-Odunola
- Department of Pharmaceutical and Medicinal Chemistry, University of Ilorin, Ilorin, Nigeria
| | - Andrew Owen
- Department of Molecular and Clinical Pharmacology, University of Liverpool, 70 Pembroke Place, Liverpool, L69 3GF, UK
| | - Saye Khoo
- Department of Molecular and Clinical Pharmacology, University of Liverpool, 70 Pembroke Place, Liverpool, L69 3GF, UK
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20
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Kang SY, Battle KE, Gibson HS, Cooper LV, Maxwell K, Kamya M, Lindsay SW, Dorsey G, Greenhouse B, Rodriguez-Barraquer I, Reiner RCJ, Smith DL, Bisanzio D. Heterogeneous exposure and hotspots for malaria vectors at three study sites in Uganda. Gates Open Res 2018; 2:32. [PMID: 30706054 PMCID: PMC6350504 DOI: 10.12688/gatesopenres.12838.2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2018] [Indexed: 11/30/2022] Open
Abstract
Background: Heterogeneity in malaria transmission has household, temporal, and spatial components. These factors are relevant for improving the efficiency of malaria control by targeting heterogeneity. To quantify variation, we analyzed mosquito counts from entomological surveillance conducted at three study sites in Uganda that varied in malaria transmission intensity. Mosquito biting or exposure is a risk factor for malaria transmission. Methods: Using a Bayesian zero-inflated negative binomial model, validated via a comprehensive simulation study, we quantified household differences in malaria vector density and examined its spatial distribution. We introduced a novel approach for identifying changes in vector abundance hotspots over time by computing the Getis-Ord statistic on ratios of household biting propensities for different scenarios. We also explored the association of household biting propensities with housing and environmental covariates. Results: In each site, there was evidence for hot and cold spots of vector abundance, and spatial patterns associated with urbanicity, elevation, or other environmental covariates. We found some differences in the hotspots in rainy vs. dry seasons or before vs. after the application of control interventions. Housing quality explained a portion of the variation among households in mosquito counts. Conclusion: This work provided an improved understanding of heterogeneity in malaria vector density at the three study sites in Uganda and offered a valuable opportunity for assessing whether interventions could be spatially targeted to be aimed at abundance hotspots which may increase malaria risk. Indoor residual spraying was shown to be a successful measure of vector control interventions in Tororo, Uganda. Cement walls, brick floors, closed eaves, screened airbricks, and tiled roofs were features of a house that had shown reduction of household biting propensity. Improvements in house quality should be recommended as a supplementary measure for malaria control reducing risk of infection.
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Affiliation(s)
- Su Yun Kang
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Katherine E Battle
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Harry S Gibson
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Laura V Cooper
- Department of Veterinary Medicine, Cambridge University, Cambridge, UK
| | - Kilama Maxwell
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Moses Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | | | - Robert C Jr Reiner
- Institute for Health Metrics & Evaluation, University of Washington, Seattle, WA, USA
| | - David L Smith
- Institute for Health Metrics & Evaluation, University of Washington, Seattle, WA, USA
| | - Donal Bisanzio
- RTI International, Washington DC, USA.,Centre for Tropical Diseases, Sacro Cuore-Don Calabria Hospital, Negrar, Italy
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21
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Hellewell J, Walker P, Ghani A, Rao B, Churcher TS. Using ante-natal clinic prevalence data to monitor temporal changes in malaria incidence in a humanitarian setting in the Democratic Republic of Congo. Malar J 2018; 17:312. [PMID: 30157850 PMCID: PMC6114784 DOI: 10.1186/s12936-018-2460-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 08/17/2018] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND The number of clinical cases of malaria is often recorded in resource constrained or conflict settings as a proxy for disease burden. Interpreting case count data in areas of humanitarian need is challenging due to uncertainties in population size caused by security concerns, resource constraints and population movement. Malaria prevalence in women visiting ante-natal care (ANC) clinics has the potential to be an easier and more accurate metric for malaria surveillance that is unbiased by population size if malaria testing is routinely conducted irrespective of symptoms. METHODS A suite of distributed lag non-linear models was fitted to clinical incidence time-series data in children under 5 years and ANC prevalence data from health centres run by Médecins Sans Frontières in the Democratic Republic of Congo, which implement routine intermittent screening and treatment alongside intermittent preventative treatment in pregnancy. These statistical models enable the temporal relationship between the two metrics to be disentangled. RESULTS There was a strong relationship between the ANC prevalence and clinical incidence suggesting that both can be used to describe current malaria endemicity. There was no evidence that ANC prevalence could predict future clinical incidence, though a change in clinical incidence was shown to influence ANC prevalence up to 3 months into the future. CONCLUSIONS The results indicate that ANC prevalence may be a suitable metric for retrospective evaluations of the impact of malaria interventions and is a useful method for evaluating long-term malaria trends in resource constrained settings.
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Affiliation(s)
- Joel Hellewell
- MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK.
| | - Patrick Walker
- MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK
| | - Azra Ghani
- MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK
| | - Bhargavi Rao
- Manson Unit, Médecins Sans Frontières (Operational Centre Amsterdam), London, UK
| | - Thomas S Churcher
- MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, UK
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22
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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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23
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Kang SY, Battle KE, Gibson HS, Cooper LV, Maxwell K, Kamya M, Lindsay SW, Dorsey G, Greenhouse B, Rodriguez-Barraquer I, Reiner RCJ, Smith DL, Bisanzio D. Heterogeneous exposure and hotspots for malaria vectors at three study sites in Uganda. Gates Open Res 2018. [DOI: 10.12688/gatesopenres.12838.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background: Heterogeneity in malaria transmission has household, temporal, and spatial components. These factors are relevant for improving the efficiency of malaria control by targeting heterogeneity. To quantify variation, we analyzed mosquito counts from entomological surveillance conducted at three study sites in Uganda that varied in malaria transmission intensity. Methods: Using a Bayesian zero-inflated negative binomial model, validated via a comprehensive simulation study, we quantified household differences in malaria vector density and examined its spatial distribution. We introduced a novel approach for identifying changes in malaria hotspots over time by computing the Getis-Ord statistic on ratios of household biting propensities for different scenarios. We also explored the association of household biting propensities with housing and environmental covariates. Results: In each site, there was evidence for hot and cold spots, spatial patterns associated with urbanicity, elevation, or other environmental covariates. We found some differences in the hotspots in rainy vs. dry seasons or before vs. after the application of control interventions. Housing quality explained a portion of the variation among households in mosquito counts. Conclusion: This work provided an improved understanding of heterogeneity in malaria vector density at the three study sites in Uganda and offered a valuable opportunity for assessing whether interventions could be spatially targeted to be aimed at hotspots of malaria risk. Indoor residual spraying was shown to be a successful measure of vector control interventions in Tororo, Uganda. Cement walls, brick floors, closed eaves, screened airbricks, and tiled roofs were features of a house that had shown protective effects towards malaria risk. Improvements in house quality should be recommended as a supplementary measure for malaria control.
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24
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Berry I, Walker P, Tagbor H, Bojang K, Coulibaly SO, Kayentao K, Williams J, Oduro A, Milligan P, Chandramohan D, Greenwood B, Cairns M. Seasonal Dynamics of Malaria in Pregnancy in West Africa: Evidence for Carriage of Infections Acquired Before Pregnancy Until First Contact with Antenatal Care. Am J Trop Med Hyg 2017; 98:534-542. [PMID: 29210351 PMCID: PMC5929207 DOI: 10.4269/ajtmh.17-0620] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In malaria-endemic areas, Plasmodium falciparum prevalence is often high in young women because of 1) low use of insecticide-treated nets before their first pregnancy and 2) acquired immunity, meaning infections are asymptomatic and thus untreated. Consequently, a common source of malaria in pregnancy (MiP) may be infected women becoming pregnant, rather than pregnant women becoming infected. In this study, prevalence of infection was determined by microscopy at first antenatal care (ANC) visit in primigravidae and secundigravidae in Ghana, Burkina Faso, Mali, and The Gambia, four countries with strong seasonal variations in transmission. Duration of pregnancy spent in the rainy season and other risk factors for infection were evaluated using multivariable Poisson regression. We found that the overall prevalence of malaria at first ANC was generally high and increased with time spent pregnant during the rainy season: prevalence among those with the longest exposure was 59.7% in Ghana, 56.7% in Burkina Faso, 42.2% in Mali, and 16.8% in Gambia. However, the prevalence was substantial even among women whose entire pregnancy before first ANC had occurred in the dry season: 41.3%, 34.4%, 11.5%, and 7.8%, respectively, in the four countries. In multivariable analysis, risk of infection was also higher among primigravidae, younger women, and those of lower socioeconomic status, independent of seasonality. High prevalence among women without exposure to high transmission during their pregnancy suggests that part of the MiP burden results from long-duration infections, including those acquired preconception. Prevention of malaria before pregnancy is needed to reduce the MiP burden.
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Affiliation(s)
- Isha Berry
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Harry Tagbor
- University of Health and Allied Sciences, Ho, Ghana
| | | | | | - Kassoum Kayentao
- Malaria Research and Training Center, Faculty of Medicine and Odontostomatology, University of Sciences, Techniques and Technologies, Bamako, Mali
| | | | | | - Paul Milligan
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Brian Greenwood
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Matthew Cairns
- London School of Hygiene and Tropical Medicine, London, United Kingdom
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25
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Mfueni Bikundi E, Coppieters Y. Importance of risk factors associated with malaria for Sub-Saharan African children. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2017; 27:394-408. [PMID: 28786293 DOI: 10.1080/09603123.2017.1359241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 07/16/2017] [Indexed: 06/07/2023]
Abstract
To assess the importance of malaria risk factors for children in sub-Saharan African countries. 61,292 children of 16 countries from DHS and MIS surveys were included in analysis. A regression model with analyse of variance and plots of mean decrease accuracy and mean decrease Gini indices were performed. The most important risk factor was the country and it contributed 52.33 % to the variance of the model. Wealth status of the child's family was the first socio-economic factor which contributed more to the difference of malaria risk among African children. There was no geographic factor among the five most important variables. Quantity of precipitation was the sixth most important factor. Our study has the potential for driving control effort in the fight against malaria in the continent which represent the majority of global malaria cases. The study indicates that, when implementing health policies, community characteristics must be taken into account.
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Affiliation(s)
- Elvire Mfueni Bikundi
- a Epidemiology, Biostatistics and Clinical Research Center, School of Public Health , Université Libre de Bruxelles (ULB) , Brussels , Belgium
| | - Yves Coppieters
- a Epidemiology, Biostatistics and Clinical Research Center, School of Public Health , Université Libre de Bruxelles (ULB) , Brussels , Belgium
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26
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Bretscher MT, Griffin JT, Ghani AC, Okell LC. Modelling the benefits of long-acting or transmission-blocking drugs for reducing Plasmodium falciparum transmission by case management or by mass treatment. Malar J 2017; 16:341. [PMID: 28814310 PMCID: PMC5559805 DOI: 10.1186/s12936-017-1988-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 08/09/2017] [Indexed: 11/16/2022] Open
Abstract
Background Anti-malarial drugs are an important tool for malaria control and elimination. Alongside their direct benefit in the treatment of disease, drug use has a community-level effect, clearing the reservoir of infection and reducing onward transmission of the parasite. Different compounds potentially have different impacts on transmission—with some providing periods of prolonged chemoprophylaxis whilst others have greater transmission-blocking potential. The aim was to quantify the relative benefit of such properties for transmission reduction to inform target product profiles in the drug development process and choice of first-line anti-malarial treatment in different endemic settings. Methods A mathematical model of Plasmodium falciparum epidemiology was used to estimate the transmission reduction that can be achieved by using drugs of varying chemoprophylactic (protection for 3, 30 or 60 days) or transmission-blocking activity (blocking 79, 92 or 100% of total onward transmission). Simulations were conducted at low, medium or high transmission intensity (slide-prevalence in 2–10 year olds being 1, 10 or 40%, respectively), with drugs administered either via case management or mass drug administration (MDA). Results Transmission reductions depend strongly on deployment strategy, treatment coverage and endemicity level. Transmission-blocking was most effective at low endemicity, whereas chemoprophylaxis was most useful at high endemicity levels. Increasing the duration of protection as much as possible was beneficial. Increasing transmission-blocking activity from the level of ACT to a 100% transmission-blocking drug (close to the effect estimated for ACT combined with primaquine) produced moderate impact but was not as effective as increasing the duration of protection in medium-to-high transmission settings (slide prevalence 10–40%). Combining both good transmission-blocking activity (e.g. as achieved by ACT or ACT + primaquine) and a long duration of protection (30 days or more, such as provided by piperaquine or mefloquine) within a drug regimen can substantially increase impact compared with drug regimens with only one of these properties in medium to high transmission areas (slide-prevalence in 2–10 year olds ~10 to 40%). These results applied whether the anti-malarials were used for case management or for MDA. Discussion These results emphasise the importance of increasing access to treatment for routine case management, and the potential value of choosing first-line anti-malarial treatment policies according to local malaria epidemiology to maximise impact on transmission. There is no indication that the optimal drug choice should differ between delivery via case management or MDA. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1988-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michael T Bretscher
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis & Modelling, Imperial College, London, UK.,F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Jamie T Griffin
- School of Mathematical Sciences, Queen Mary University of London, London, UK
| | - Azra C Ghani
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis & Modelling, Imperial College, London, UK
| | - Lucy C Okell
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis & Modelling, Imperial College, London, UK.
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27
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Aboagye SY, Ampah KA, Ross A, Asare P, Otchere ID, Fyfe J, Yeboah-Manu D. Seasonal Pattern of Mycobacterium ulcerans, the Causative Agent of Buruli Ulcer, in the Environment in Ghana. MICROBIAL ECOLOGY 2017; 74:350-361. [PMID: 28238016 PMCID: PMC5496970 DOI: 10.1007/s00248-017-0946-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 01/31/2017] [Indexed: 06/06/2023]
Abstract
This study aimed to contribute to the understanding of Mycobacterium ulcerans (MU) ecology by analysing both clinical and environmental samples collected from ten communities along two major river basins (Offin and Densu) associated with Buruli ulcer (BU) at different seasons. We collected clinical samples from presumptive BU cases and environmental samples from ten communities. Following DNA extraction, clinical samples were confirmed by IS2404 PCR and environmental samples were confirmed by targeting MU-specific genes, IS2404, IS2606 and the ketoreductase (KR) using real-time PCR. Environmental samples were first analysed for IS2404; after which, IS2404-positive samples were multiplexed for the IS2606 and KR gene. Our findings indicate an overall decline in BU incidence along both river basins, although incidence at Densu outweighs that of Offin. Overall, 1600 environmental samples were screened along Densu (434, 27 %) and Offin (1166, 73 %) and MU was detected in 139 (9 %) of the combined samples. The positivity of MU along the Densu River basin was 89/434 (20.5 %), whilst that of the Offin River basin was 50/1166 (4.3 %). The DNA was detected mainly in snails (5/6, 83 %), moss (8/40, 20 %), soil (55/586, 9 %) and vegetation (55/675, 8 %). The proportion of MU positive samples recorded was higher during the months with higher rainfall levels (126/1175, 11 %) than during the dry season months (13/425, 3 %). This study indicates for the first time that there is a seasonal pattern in the presence of MU in the environment, which may be related to recent rainfall or water in the soil.
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Affiliation(s)
- Samuel Yaw Aboagye
- Bacteriology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O. Box LG 581, Legon, Accra, Ghana
- Institute of Environmental and Sanitation Studies, University of Ghana, Accra, Ghana
| | - Kobina Assan Ampah
- Bacteriology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O. Box LG 581, Legon, Accra, Ghana
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Prince Asare
- Bacteriology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O. Box LG 581, Legon, Accra, Ghana
| | - Isaac Darko Otchere
- Bacteriology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O. Box LG 581, Legon, Accra, Ghana
| | - Janet Fyfe
- Victorian Infectious Diseases Reference Laboratory, Melbourne, VIC, Australia
| | - Dorothy Yeboah-Manu
- Bacteriology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, P.O. Box LG 581, Legon, Accra, Ghana.
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28
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Slater HC, Okell LC, Ghani AC. Mathematical Modelling to Guide Drug Development for Malaria Elimination. Trends Parasitol 2017; 33:175-184. [PMID: 27727128 PMCID: PMC5347022 DOI: 10.1016/j.pt.2016.09.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 09/05/2016] [Accepted: 09/12/2016] [Indexed: 11/16/2022]
Abstract
Mathematical models of the dynamics of a drug within the host are now frequently used to guide drug development. These generally focus on assessing the efficacy and duration of response to guide patient therapy. Increasingly, antimalarial drugs are used at the population level, to clear infections, provide chemoprevention, and to reduce onward transmission of infection. However, there is less clarity on the extent to which different drug properties are important for these different uses. In addition, the emergence of drug resistance poses new threats to longer-term use and highlights the need for rational drug development. Here, we argue that integrating within-host pharmacokinetic and pharmacodynamic (PK/PD) models with mathematical models for the population-level transmission of malaria is key to guiding optimal drug design to aid malaria elimination.
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Affiliation(s)
- Hannah C Slater
- MRC Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, UK
| | - Lucy C Okell
- MRC Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, UK
| | - Azra C Ghani
- MRC Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, UK.
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29
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Tripura R, Peto TJ, Chalk J, Lee SJ, Sirithiranont P, Nguon C, Dhorda M, von Seidlein L, Maude RJ, Day NPJ, Imwong M, White NJ, Dondorp AM. Persistent Plasmodium falciparum and Plasmodium vivax infections in a western Cambodian population: implications for prevention, treatment and elimination strategies. Malar J 2016; 15:181. [PMID: 27013512 PMCID: PMC4806483 DOI: 10.1186/s12936-016-1224-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 03/10/2016] [Indexed: 11/10/2022] Open
Abstract
Background Subclinical Plasmodium parasitaemia is an important reservoir for the transmission and persistence of malaria, particularly in low transmission areas. Methods Using ultrasensitive quantitative PCR (uPCR) for the detection of parasitaemia, the entire population of three Cambodian villages in Pailin province were followed for 1 year at three-monthly intervals. A cohort of adult participants found initially to have asymptomatic malaria parasitaemia was followed monthly over the same period. Results The initial cross sectional survey in June 2013 (M0) of 1447 asymptomatic residents found that 32 (2.2 %) had Plasmodium falciparum, 48 (3.3 %) had P. vivax, 4 (0.3 %) had mixed infections and in 142/1447 (9.8 %) malaria was detected but there was insufficient DNA to identify the species (Plasmodium. species). Polymorphisms in the ‘K13-propeller’ associated with reduced susceptibility to artemisinin derivatives (C580Y) were found in 17/32 (51 %) P. falciparum strains. Monthly follow-up without treatment of 24 adult participants with asymptomatic mono or mixed P. falciparum infections found that 3/24 (13 %) remained parasitaemic for 2–4 months, whereas the remaining 21/24 (87 %) participants had cleared their parasitaemia after 1 month. In contrast, 12/34 (35 %) adult participants with P. vivax mono-infection at M0 had malaria parasites (P. vivax or P. sp.) during four or more of the following 11 monthly surveys. Conclusions This longitudinal survey in a low transmission setting shows limited duration of P. falciparum carriage, but prolonged carriage of P. vivax infections. Radical treatment of P. vivax infections by 8-aminoquinoline regimens may be required to eliminate all malaria from Cambodia. Trial registration ClinicalTrials.gov NCT01872702 Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1224-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rupam Tripura
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
| | - Thomas J Peto
- 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
| | - Jeremy Chalk
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Sue J Lee
- 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
| | - Pasathorn Sirithiranont
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Chea Nguon
- National Centre for Parasitology, Entomology, and Malaria Control (CNM), Trapeng Svay Village, Sangkat Phnom Penh Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Mehul Dhorda
- WorldWide Antimalarial Resistance Network, Asia Regional Centre, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Lorenz von Seidlein
- 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.,Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, 02115, USA
| | - 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.,Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Nicholas P J Day
- 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
| | - Mallika Imwong
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nicholas J White
- 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
| | - Arjen M Dondorp
- 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
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30
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Tagbor H, Antwi GD, Acheampong PR, Bart Plange C, Chandramohan D, Cairns M. Seasonal malaria chemoprevention in an area of extended seasonal transmission in Ashanti, Ghana: an individually randomised clinical trial. Trop Med Int Health 2015; 21:224-35. [PMID: 26578353 PMCID: PMC4982104 DOI: 10.1111/tmi.12642] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Objective To investigate the effectiveness of seasonal malaria chemoprevention (SMC) and community case management with long‐acting artemisinin‐based combination therapies (ACTs) for the control of malaria in areas of extended seasonal malaria transmission. Method Individually randomised, placebo‐controlled trial in the Ashanti Region of Ghana. A total of 2400 children aged 3–59 months received either: (i) a short‐acting ACT for case management of malaria (artemether‐lumefantrine, AL) plus placebo SMC, or (ii) a long‐acting ACT (dihydroartemisinin‐piperaquine, DP) for case management plus placebo SMC or (iii) AL for case management plus active SMC with sulphadoxine‐pyrimethamine and amodiaquine. SMC or placebo was delivered on five occasions during the rainy season. Malaria cases were managed by community health workers, who used rapid diagnostic tests to confirm infection prior to treatment. Results The incidence of malaria was lower in children given SMC during the rainy season. Compared to those given placebo SMC and AL for case management, the adjusted hazard ratio (aHR) was 0.62 (95% CI: 0.41, 0.93), P = 0.020 by intention to treat and 0.53 (95% CI: 0.29, 0.95), P = 0.033 among children given five SMC courses. There were no major differences between groups given different ACTs for case management (aHR DP vs. AL 1.18 (95% CI 0.83, 1.67), P = 0.356). Conclusion SMC may have an important public health impact in areas with a longer transmission season, but further optimisation of SMC schedules is needed to maximise its impact in such settings.
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Affiliation(s)
- Harry Tagbor
- School of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.,Centre for Global Health Research, Juaben, Ghana
| | | | | | | | - Daniel Chandramohan
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Matthew Cairns
- MRC Tropical Epidemiology Group, London School of hygiene and tropical medicine, London, UK
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