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Waltmann A, Chen JS, Duncan JA. Promising developments in gonococcal vaccines. Curr Opin Infect Dis 2024; 37:63-69. [PMID: 38050729 DOI: 10.1097/qco.0000000000000992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
PURPOSE OF REVIEW While effective vaccines to prevent invasive infections by Neisseria meningitidis have been deployed around the world, development of a vaccine to prevent Neisseria gonorrhoeae has lagged. After multiple failed vaccine candidates, vaccine development for N. gonorrhoeae is showing promise for the first time in several decades. This review highlights recent progress in the field. RECENT FINDINGS Vaccines containing outer-membrane vesicles (OMV) have been used to manage outbreaks of the serogroup B N. meningitidis in a number of countries. Epidemiologic studies indicate these vaccination campaigns were associated with reductions in reported N. gonorrhoeae infections. Recently, a serogroup B N. meningitidis vaccine containing both recombinant antigens and OMV has been licensed through much of the world. Epidemiologic studies also demonstrate associations between 4CMenB immunization and reduced N. gonorrhoeae infections. Additionally, mathematical modeling studies have begun to identify potential strategies for vaccine deployment to maximize reduction of infections. SUMMARY After several decades with little progress towards an effective gonococcal vaccine, large observational studies have provided evidence that a new generation of group B N. meningitidis vaccines containing OMV have serendipitously restarted the field. Ongoing clinical trials will soon provide definitive evidence regarding the efficacy of these vaccines in preventing N. gonorrhoeae infection.
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Affiliation(s)
- Andreea Waltmann
- Division of Infectious Diseases, Department of Medicine, School of Medicine
- Institute for Global Health and Infectious Diseases
| | - Jane S Chen
- Institute for Global Health and Infectious Diseases
- Department of Health Behavior, Gillings School of Global Public Health, University of North Carolina at Chapel Hill
| | - Joseph A Duncan
- Division of Infectious Diseases, Department of Medicine, School of Medicine
- Institute for Global Health and Infectious Diseases
- Department of Pharmacology, School of Medicine
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Hakim JMC, Waltmann A, Tinajeros F, Kharabora O, Machaca EM, Calderon M, del Carmen Menduiña M, Wang J, Rueda D, Zimic M, Verástegui M, Juliano JJ, Gilman RH, Mugnier MR, Bowman NM. Amplicon Sequencing Reveals Complex Infection in Infants Congenitally Infected With Trypanosoma Cruzi and Informs the Dynamics of Parasite Transmission. J Infect Dis 2023; 228:769-776. [PMID: 37119236 PMCID: PMC10503952 DOI: 10.1093/infdis/jiad125] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 02/08/2023] [Accepted: 04/26/2023] [Indexed: 05/01/2023] Open
Abstract
Congenital transmission of Trypanosoma cruzi is an important source of new Chagas infections worldwide. The mechanisms of congenital transmission remain poorly understood, but there is evidence that parasite factors are involved. Investigating changes in parasite strain diversity during transmission could provide insight into the parasite factors that influence the process. Here we use amplicon sequencing of a single copy T. cruzi gene to evaluate the diversity of infection in clinical samples from Chagas positive mothers and their infected infants. Several infants and mothers were infected with multiple parasite strains, mostly of the same TcV lineage, and parasite strain diversity was higher in infants than mothers. Two parasite haplotypes were detected exclusively in infant samples, while one haplotype was never found in infants. Together, these data suggest multiple parasites initiate a congenital infection and that parasite factors influence the probability of vertical transmission.
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Affiliation(s)
- Jill M C Hakim
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Andreea Waltmann
- Institute for Global Health and Infectious Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | | | - Oksana Kharabora
- Institute for Global Health and Infectious Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Edith Málaga Machaca
- Asociación Benéfica PRISMA, Lima, Peru
- Infectious Diseases Research Laboratory, Department of Cellular and Molecular Sciences, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Maritza Calderon
- Infectious Diseases Research Laboratory, Department of Cellular and Molecular Sciences, Universidad Peruana Cayetano Heredia, Lima, Perú
| | | | - Jeremy Wang
- University of North Carolina, Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | - Daniel Rueda
- Facultad de Ciencias, Universidad Nacional de Ingeniería, Lima, Perú
| | - Mirko Zimic
- Infectious Diseases Research Laboratory, Department of Cellular and Molecular Sciences, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Manuela Verástegui
- Infectious Diseases Research Laboratory, Department of Cellular and Molecular Sciences, Universidad Peruana Cayetano Heredia, Lima, Perú
| | - Jonathan J Juliano
- Institute for Global Health and Infectious Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
| | - Robert H Gilman
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Monica R Mugnier
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Natalie M Bowman
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA
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Waltmann A, Balthazar JT, Begum AA, Hua N, Jerse AE, Shafer WM, Hobbs MM, Duncan JA. Neisseria gonorrhoeae MtrCDE Efflux Pump During In Vivo Experimental Genital Tract Infection in Men and Mice Reveals the Presence of Within-Host Colonization Bottleneck. medRxiv 2023:2023.06.23.23291824. [PMID: 37425726 PMCID: PMC10327229 DOI: 10.1101/2023.06.23.23291824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
The MtrCDE efflux pump of Neisseria gonorrhoeae exports a wide range of antimicrobial compounds that the gonococcus encounters at mucosal surfaces during colonization and infection. Here, we evaluate the role of this efflux pump system in strain FA1090 in human male urethral infection with a Controlled Human Infection Model. Using the strategy of competitive multi-strain infection with wild-type FA1090 and an isogenic mutant strain that does not contain a functional MtrCDE pump, we found that the presence of the efflux pump during human experimental infection did not confer a competitive advantage. This finding is in contrast to previous findings in female mice, which demonstrated that gonococci of strain FA19 lacking a functional MtrCDE pump had a significantly reduced fitness compared to the wild type strain in the lower genital tract of female mice. We conducted competitive infections in female mice with FA19 and FA1090 strains, including mutants that do not assemble a functional Mtr efflux pump, demonstrating the fitness advantage provided byt the MtrCDE efflux pump during infection of mice is strain dependent. Our data indicate that new gonorrhea treatment strategies targeting the MtrCDE efflux pump functions may not be universally efficacious in naturally occurring infections. Owing to the equal fitness of FA1090 strains in men, our experiments unexpectedly demonstrated the likely presence of an early colonization bottleneck of N. gonorrhoeae in the human male urethra. TRIAL REGISTRATION Clinicaltrials.gov NCT03840811 .
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Sandfort M, Monteiro W, Lacerda M, Nguitragool W, Sattabongkot J, Waltmann A, Salje H, Vantaux A, Witkowski B, Robinson LJ, Mueller I, White M. The spatial signature of Plasmodium vivax and Plasmodium falciparum infections: quantifying the clustering of infections in cross-sectional surveys and cohort studies. Malar J 2023; 22:75. [PMID: 36870976 PMCID: PMC9985228 DOI: 10.1186/s12936-023-04515-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 02/25/2023] [Indexed: 03/06/2023] Open
Abstract
BACKGROUND Over the last decades, enormous successes have been achieved in reducing malaria burden globally. In Latin America, South East Asia, and the Western Pacific, many countries now pursue the goal of malaria elimination by 2030. It is widely acknowledged that Plasmodium spp. infections cluster spatially so that interventions need to be spatially informed, e.g. spatially targeted reactive case detection strategies. Here, the spatial signature method is introduced as a tool to quantify the distance around an index infection within which other infections significantly cluster. METHODS Data were considered from cross-sectional surveys from Brazil, Thailand, Cambodia, and Solomon Islands, conducted between 2012 and 2018. Household locations were recorded by GPS and finger-prick blood samples from participants were tested for Plasmodium infection by PCR. Cohort studies from Brazil and Thailand with monthly sampling over a year from 2013 until 2014 were also included. The prevalence of PCR-confirmed infections was calculated at increasing distance around index infections (and growing time intervals in the cohort studies). Statistical significance was defined as prevalence outside of a 95%-quantile interval of a bootstrap null distribution after random re-allocation of locations of infections. RESULTS Prevalence of Plasmodium vivax and Plasmodium falciparum infections was elevated in close proximity around index infections and decreased with distance in most study sites, e.g. from 21.3% at 0 km to the global study prevalence of 6.4% for P. vivax in the Cambodian survey. In the cohort studies, the clustering decreased with longer time windows. The distance from index infections to a 50% reduction of prevalence ranged from 25 m to 3175 m, tending to shorter distances at lower global study prevalence. CONCLUSIONS The spatial signatures of P. vivax and P. falciparum infections demonstrate spatial clustering across a diverse set of study sites, quantifying the distance within which the clustering occurs. The method offers a novel tool in malaria epidemiology, potentially informing reactive intervention strategies regarding radius choices of operations around detected infections and thus strengthening malaria elimination endeavours.
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Affiliation(s)
- Mirco Sandfort
- Unité Malaria : Parasites Et Hôtes, Département Parasites Et Insectes Vecteurs, Institut Pasteur, Paris, France. .,Sorbonne Université, Collège Doctoral, Paris, France.
| | - Wuelton Monteiro
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil.,Universidade do Estado do Amazonas, Manaus, Brazil
| | - Marcus Lacerda
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil.,Universidade do Estado do Amazonas, Manaus, Brazil.,Instituto de Pesquisas Leônidas e Maria Deane, Manaus, Brazil
| | - Wang Nguitragool
- Department of Molecular Tropical Medicine & Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Andreea Waltmann
- Population Health & Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Henrik Salje
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Amélie Vantaux
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Benoit Witkowski
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Leanne J Robinson
- Population Health & Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Australia.,Burnet Institute, Melbourne, Australia
| | - Ivo Mueller
- Unité Malaria : Parasites Et Hôtes, Département Parasites Et Insectes Vecteurs, Institut Pasteur, Paris, France.,Population Health & Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Michael White
- Unité Malaria : Parasites Et Hôtes, Département Parasites Et Insectes Vecteurs, Institut Pasteur, Paris, France.,G5 Épidémiologie et Analyse des Maladies Infectieuses, Département de Santé Globale, Institut Pasteur, Paris, France
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Waltmann A, Thomas C, Duncan JA. The role of the genital microbiota in the acquisition and pathogenesis of sexually transmitted infections. Curr Opin Infect Dis 2023; 36:35-48. [PMID: 36729748 PMCID: PMC10500551 DOI: 10.1097/qco.0000000000000893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE OF REVIEW There are an estimated 374 million new sexually transmitted infections (STIs) worldwide every year. Our review article examines the current evidence of how STI acquisition, transmission, and pathogenesis is impacted upon by the genital microbiota, with a focus on epidemiological, biochemical, and immunological features. RECENT FINDINGS At least in women, a genital microbiota dominated by lactobacilli has long been considered optimal for reproductive health, while depletion of lactobacilli may lead to a genital microenvironment dominated by anaerobic pathogens, which can manifest clinically as bacterial vaginosis. Recent research efforts have characterized genital microbiota composition in greater resolution, sometimes at species-level, using proteomics, metabolomics, and deep sequencing. This has enhanced our understanding of how specific microbiota members influence acquisition or clinical manifestation of STI pathogen infection. Other advances include a steady, though still slow, increase in the number of studies that sought to determine the genital (penile or urethral) microbiota of males and how it may impact that of their female partners' genital microbiota and risk of STI acquisition. Altogether, these data enabled us to explore the concept that genital microbiota may be sexually transmitted and influence pathogenesis and clinical presentation of other STI. SUMMARY With STI infection rates increasing worldwide, it is important now more than ever to find novel STI prevention strategies. Understanding if and how the genital microbiota is a modifiable risk factor for STI transmission, acquisition, and clinical manifestation may prove to be an important strategy in our efforts to curb morbidity in at risk populations.
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Affiliation(s)
- Andreea Waltmann
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC, United States
- Institute for Global Health & Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Cynthia Thomas
- Graduate Program, Department of Microbiology and Immunology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Joseph A Duncan
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina, Chapel Hill, NC, United States
- Institute for Global Health & Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
- Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill, NC, United States
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
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Waltmann A, Duncan JA, Pier GB, Cywes-Bentley C, Cohen MS, Hobbs MM. Experimental Urethral Infection with Neisseria gonorrhoeae. Curr Top Microbiol Immunol 2022:10.1007/82_2021_250. [PMID: 35246736 PMCID: PMC9441470 DOI: 10.1007/82_2021_250] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Gonorrhea rates and antibiotic resistance are both increasing. Neisseria gonorrhoeae (Ng) is an exclusively human pathogen and is exquisitely adapted to its natural host. Ng can subvert immune responses and undergoes frequent antigenic variation, resulting in limited immunity and protection from reinfection. Previous gonococcal vaccine efforts have been largely unsuccessful, and the last vaccine to be tested in humans was more than 35 years ago. Advancing technologies and the threat of untreatable gonorrhea have fueled renewed pursuit of a vaccine as a long-term sustainable solution for gonorrhea control. Despite the development of a female mouse model of genital gonococcal infection two decades ago, correlates of immunity or protection remain largely unknown, making the gonococcus a challenging vaccine target. The controlled human urethral infection model of gonorrhea (Ng CHIM) has been used to study gonococcal pathogenesis and the basis of anti-gonococcal immunity. Over 200 participants have been inoculated without serious adverse events. The Ng CHIM replicates the early natural course of urethral infection. We are now at an inflexion point to pivot the use of the model for vaccine testing to address the urgency of improved gonorrhea control. Herein we discuss the need for gonorrhea vaccines, and the advantages and limitations of the Ng CHIM in accelerating the development of gonorrhea vaccines.
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Affiliation(s)
- Andreea Waltmann
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Joseph A Duncan
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Gerald B Pier
- Brigham and Women's Hospital, Harvard Medical School, Boston, USA
| | | | - Myron S Cohen
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Marcia M Hobbs
- School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, USA.
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7
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Waltmann A, McQuade ETR, Chinkhumba J, Operario DJ, Mzembe E, Itoh M, Kayange M, Puerto-Meredith SM, Mathanga DP, Juliano JJ, Carroll I, Bartelt LA, Gutman JR, Meshnick SR. The positive effect of malaria IPTp-SP on birthweight is mediated by gestational weight gain but modifiable by maternal carriage of enteric pathogens. EBioMedicine 2022; 77:103871. [PMID: 35217408 PMCID: PMC8866062 DOI: 10.1016/j.ebiom.2022.103871] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 01/24/2022] [Accepted: 01/24/2022] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Poor pregnancy and birth outcomes are common in sub-Saharan Africa and have complex aetiologies. Sulfadoxine-pyrimethamine (SP), given for intermittent preventive therapy of malaria in pregnancy (IPTp), is one of few existing interventions that improves outcomes of both mother and baby despite widespread SP-resistant malaria. Compelling evidence exists that malaria-independent pathways contribute to this protective effect, but the exact sources of non anti-malarial protection remained unknown. We hypothesized that the beneficial effect of SP on birthweight is mediated by SP activity on maternal factors, including increased gestational weight gain and antibiotic activity on pathogens in the maternal gut. METHODS Expectant mothers from a larger randomized control trial comparing the efficacy of IPTp-SP to IPTp with dihydroartemisinin-piperaquine (DP) were also enrolled in this sub-study study at their first antenatal care visit before commencement of IPTp (n = 105). Participants were followed monthly until delivery. Weights and mid-to-upper-arm circumferences (MUAC) were recorded. Monthly stool samples were collected and screened for five Escherichia coli pathotypes, Shigella spp., Vibrio cholerae, Salmonella, Campylobacter coli/jejuni, and three protozoa (Giardia spp., Entameba histolytica, and Cryptosporidium spp.) using previously validated molecular assays. FINDINGS IPTp-SP vs. IPTP-DP was associated with higher maternal gestational weight gain (GWG) and nutritional indicators (MUAC and body-mass index, BMI). GWG was found to be a mediator of the birthweight and IPTp-SP relationship, as the birthweight of SP infants, but not DP infants, varied according to maternal GWG. The burden of maternal enteric infections was high. The three most commonly observed pathogens were enteroaggregative E. coli (EAEC), atypical enteropathogenic E.coli/enterohaemorrhagic E. coli (aEPEC/EHEC), and typical enteropathogenic E.coli (tEPEC). We found that SP reduced the prevalence of EAEC in a dose-dependent manner. After 3 or more doses, SP-recipients were 90% less likely to be infected with EAEC compared to DP-recipients (ORadj = 0.07, CI95 = 0.12, 0.39, p = 0.002). Compared to DP, this coincided with higher maternal gestational weight gain (GWG) and nutritional indicators (MUAC and body-mass index, BMI). The beneficial effect of SP on maternal GWG, MUAC and BMI, was lower if SP mothers had detectable EAEC, aEPEC/EHEC, tEPEC, and LT-ETEC at baseline. Maternal EAEC and tEPEC at baseline associated with lower birthweight for babies of both SP mothers and DP mothers. When comparing IPTp regimens, the positive effect of SP on birthweight compared to DP was only observed for infants of women who did not test positive for EAEC at baseline (adjusted mean birthweight difference SP vs. DP = 156.0 g, CI95 = -18.0 g, 336.9 g, p = 0.087), though confidence intervals crossed the null. INTERPRETATION Our findings indicate that in pregnant Malawian women, IPTp-SP vs. IPTp-DP is consistently associated with higher MUAC, BMI, and GWG following the WHO-recommended regimen of at least 3 doses, but carriage of maternal gut pathogens before initiation of IPTp lessens this effect. Because GWG was a mediator of the association between birthweight and SP, we show that SP's previously proven positive effect on birthweight is by promoting maternal weight gain. Overall, our results present one plausible pathway SP exerts malaria-independent protection against poor birth outcomes in the context of its waning antimalarial activity and warrants further investigation. FUNDING A full list of funding bodies that contributed to this study can be found in the Acknowledgements section.
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Affiliation(s)
- Andreea Waltmann
- Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, NC, USA.
| | | | - Jobiba Chinkhumba
- Malaria Alert Centre (MAC), University of Malawi College of Medicine, Blantyre, Malawi
| | - Darwin J Operario
- Division of Infectious Diseases & International Health, Department of Medicine, University of Virginia, VA, USA
| | - Enala Mzembe
- Malaria Alert Centre (MAC), University of Malawi College of Medicine, Blantyre, Malawi
| | - Megumi Itoh
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | | | - Don P Mathanga
- Malaria Alert Centre (MAC), University of Malawi College of Medicine, Blantyre, Malawi
| | - Jonathan J Juliano
- Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, NC, USA; Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Ian Carroll
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Luther A Bartelt
- Department of Nutrition, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Julie R Gutman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Steven R Meshnick
- Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, NC, USA; Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
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Lovett A, Seña AC, Macintyre AN, Sempowski GD, Duncan JA, Waltmann A. Cervicovaginal Microbiota Predicts Neisseria gonorrhoeae Clinical Presentation. Front Microbiol 2022; 12:790531. [PMID: 35222300 PMCID: PMC8867028 DOI: 10.3389/fmicb.2021.790531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/13/2021] [Indexed: 01/11/2023] Open
Abstract
Neisseria gonorrhoeae infection of the female lower genital tract can present with a spectrum of phenotypes ranging from asymptomatic carriage to symptomatic cervical inflammation, or cervicitis. The factors that contribute to the development of asymptomatic or symptomatic infections are largely uncharacterized. We conducted a pilot study to assess differences in the cervicovaginal microbial community of patients presenting with symptomatic vs. asymptomatic N. gonorrhoeae infections to a sexually transmitted infections (STI) clinic. DNA was isolated from cervicovaginal swab specimens from women who tested positive for N. gonorrhoeae infection using a clinical diagnostic nucleic acid amplification test. We performed deep sequencing of 16S ribosomal RNA gene amplicons, followed by microbiome analyses with QIIME, and species-specific real-time PCR to assess the composition of microbial communities cohabitating the lower genital tract with the infecting N. gonorrhoeae. Specimens collected from asymptomatic individuals with N. gonorrhoeae infection and no co-infection with Chlamydia trachomatis and/or Trichomonas vaginalis carried Lactobacillus-dominant microbial communities more frequently than symptomatic patients without co-infection. When compared to asymptomatic individuals, symptomatic women had microbial communities characterized by more diverse and heterogenous bacterial taxa, typically associated with bacterial vaginosis (BV) [Prevotella, Sneathia, Mycoplasma hominis, and Bacterial Vaginosis-Associated Bacterium-1 (BVAB1)/"Candidatus Lachnocurva vaginae"]. Both symptomatic and asymptomatic N. gonorrhoeae patients with additional STI co-infection displayed a BV-like microbial community. These findings suggest that Lactobacillus-dominant vaginal microbial community may protect individuals from developing symptoms during lower genital tract infection with N. gonorrhoeae.
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Affiliation(s)
- Angela Lovett
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Arlene C. Seña
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States,Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Andrew N. Macintyre
- School of Medicine and Duke Human Vaccine Institute, Duke University, Durham, NC, United States
| | - Gregory D. Sempowski
- School of Medicine and Duke Human Vaccine Institute, Duke University, Durham, NC, United States
| | - Joseph A. Duncan
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States,Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States,Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Andreea Waltmann
- Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States,*Correspondence: Andreea Waltmann,
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Koepfli C, Nguitragool W, de Almeida ACG, Kuehn A, Waltmann A, Kattenberg E, Ome-Kaius M, Rarau P, Obadia T, Kazura J, Monteiro W, Darcy AW, Wini L, Bassat Q, Felger I, Sattabongkot J, Robinson LJ, Lacerda M, Mueller I. Identification of the asymptomatic Plasmodium falciparum and Plasmodium vivax gametocyte reservoir under different transmission intensities. PLoS Negl Trop Dis 2021; 15:e0009672. [PMID: 34449764 PMCID: PMC8428688 DOI: 10.1371/journal.pntd.0009672] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 09/09/2021] [Accepted: 07/21/2021] [Indexed: 11/25/2022] Open
Abstract
Background Understanding epidemiological variables affecting gametocyte carriage and density is essential to design interventions that most effectively reduce malaria human-to-mosquito transmission. Methodology/Principal findings Plasmodium falciparum and P. vivax parasites and gametocytes were quantified by qPCR and RT-qPCR assays using the same methodologies in 5 cross-sectional surveys involving 16,493 individuals in Brazil, Thailand, Papua New Guinea, and Solomon Islands. The proportion of infections with detectable gametocytes per survey ranged from 44–94% for P. falciparum and from 23–72% for P. vivax. Blood-stage parasite density was the most important predictor of the probability to detect gametocytes. In moderate transmission settings (prevalence by qPCR>5%), parasite density decreased with age and the majority of gametocyte carriers were children. In low transmission settings (prevalence<5%), >65% of gametocyte carriers were adults. Per survey, 37–100% of all individuals positive for gametocytes by RT-qPCR were positive by light microscopy for asexual stages or gametocytes (overall: P. falciparum 178/348, P. vivax 235/398). Conclusions/Significance Interventions to reduce human-to-mosquito malaria transmission in moderate-high endemicity settings will have the greatest impact when children are targeted. In contrast, all age groups need to be included in control activities in low endemicity settings to achieve elimination. Detection of infections by light microscopy is a valuable tool to identify asymptomatic blood stage infections that likely contribute most to ongoing transmission at the time of sampling. Plasmodium vivax and Plasmodium falciparum cause the vast majority of all human malaria cases. Across all transmission settings, a large proportion of infections of the two species remain asymptomatic. These infections are not diagnosed and treated by control programs focusing on clinical cases. They can carry gametocytes, the sexual stage of the parasite that establishes infections in mosquitos, thus asymptomatic infections contribute to transmission. In order to determine who is likely to contribute to transmission, gametocyte densities were measured by sensitive molecular methods in afebrile individuals in four countries. The proportion of infections with gametocytes varied greatly among surveys, and was higher in regions that had experienced low transmission for extended periods of time. In moderate-high transmission settings, gametocyte densities were particularly high in children below six years, highlighting the importance that interventions to reduce transmission include this age group. The majority of gametocyte carriers was positive by light microscopy. The comprehensive data on gametocyte carriage presented here lays the foundation for the development of more effective screen and treat activities to reduce malaria transmission.
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Affiliation(s)
- Cristian Koepfli
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Australia
- University of Notre Dame, Eck Institute for Global Health, Department of Biological Sciences, Notre Dame, Indiana, United States of America
- * E-mail:
| | - Wang Nguitragool
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Anne Cristine Gomes de Almeida
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Universidade do Estado do Amazonas, Manaus, Brazil
| | - Andrea Kuehn
- ISGlobal, Hospital Clínic—Universitat de Barcelona, Barcelona, Spain
| | - Andreea Waltmann
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Eline Kattenberg
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Maria Ome-Kaius
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Australia
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Patricia Rarau
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Thomas Obadia
- Hub de Bioinformatique et Biostatistique, Département Biologie Computationnelle, Institut Pasteur, Paris, France
- Unité Malaria: parasites et Hôtes, Département Parasites et Insectes Vecteurs, Institut Pasteur, Paris, France
| | - James Kazura
- Centre for Global Health & Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Wuelton Monteiro
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
- Universidade do Estado do Amazonas, Manaus, Brazil
| | - Andrew W. Darcy
- National Health Training and Research Institute, Ministry of Health, Honiara, Solomon Islands
| | - Lyndes Wini
- Vector Borne Diseases Program, Ministry of Health, Honiara, Solomon Islands
| | - Quique Bassat
- ISGlobal, Hospital Clínic—Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- ICREA, Barcelona, Spain
- Pediatric Infectious Diseases Unit, Pediatrics Department, Hospital Sant Joan de Déu (University of Barcelona), Barcelona, Spain
- Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Leanne J. Robinson
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Marcus Lacerda
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Manaus, Brazil
| | - Ivo Mueller
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Australia
- Unité Malaria: parasites et Hôtes, Département Parasites et Insectes Vecteurs, Institut Pasteur, Paris, France
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10
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Bowman NM, Balasubramanian S, Gilman RH, Parobek C, Calderon M, Waltmann A, Messenger LA, Sanchez L, Bern C, Juliano JJ. Deep sequencing to detect diversity of Trypanosoma cruzi infection in patients co-infected with HIV and Chagas disease. J Infect Dis 2021; 225:243-247. [PMID: 34240175 DOI: 10.1093/infdis/jiab350] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/07/2021] [Indexed: 11/12/2022] Open
Abstract
Chagas disease, caused by Trypanosoma cruzi, can reactivate and cause severe acute disease in immunocompromised patients such as those infected with HIV. We conducted amplicon deep sequencing of a 327-base pair fragment of the tcscd5 gene using an Ion Torrent PGM directly from clinical samples from HIV patients with high parasitemia. We describe the within host diversity, both characterizing the discrete typing unit (DTUs) of the infections and confirming the presence of multi-strain infections, directly from clinical samples. This method can rapidly provide information on the genetic diversity of T. cruzi infection, which can have direct impacts on clinical disease.
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Affiliation(s)
- Natalie M Bowman
- University of North Carolina at Chapel Hill School of Medicine, Department of Medicine, Division of Infectious Diseases, Chapel Hill, NC, United States
| | - Sujata Balasubramanian
- University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, United States
| | - Robert H Gilman
- Johns Hopkins Bloomberg School of Public Health, Department of International Health, Baltimore, MD, United States
| | - Christian Parobek
- University of North Carolina at Chapel Hill School of Medicine, NC, United States
| | | | - Andreea Waltmann
- University of North Carolina at Chapel Hill, Institute of Global Health and Infectious Diseases, Chapel Hill, NC, United States
| | - Louisa A Messenger
- London School of Hygiene and Tropical Medicine, Department of Disease Control, Keppel Street, London, United Kingdom
| | - Leny Sanchez
- Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Caryn Bern
- University of California-San Francisco School of Medicine, Department of Epidemiology and Biostatistics, San Francisco, CA, United States
| | - Jonathan J Juliano
- University of North Carolina at Chapel Hill School of Medicine, Department of Medicine, Division of Infectious Diseases, Chapel Hill, NC, United States
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11
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Abstract
PURPOSE OF REVIEW This review provides an update of nonviral, curable sexually transmitted infections (STIs) in pregnancy and summarizes our understanding of the current issues and controversies surrounding risk factors, screening, and treatment of STIs in pregnancy primarily in high-income countries (using the United States and the United Kingdom as examples). The infections covered in this review are syphilis, gonorrhea, chlamydia, trichomoniasis, and Mycoplasma genitalium infections. RECENT FINDINGS Overall, limited modern data is available to update researchers and clinicians on the epidemiology and care of STIs in pregnancy. Though common risk factors can be identified among these STIs, like socioeconomic status and inadequate antenatal care, specific screening and treatment challenges vary by geography and pathogen. Wherever available, surveillance data and research evidence are often limited to nonpregnant patients, leading to imperfect pregnancy-specific risk estimates and obstetric lags in the development and adoption of new guidelines. We have identified three areas of opportunity that may enhance the effectiveness of current approaches and inform new ones: improved data collection and evidence-based screening practices; prompt and comprehensive therapy, including partner services, and evaluations of new treatment modalities; and equitable antenatal and sexual healthcare for all pregnant persons and their partners. SUMMARY These findings highlight the need to revisit standards of screening and management of STIs in pregnancy in high-income countries.
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Affiliation(s)
- Andreea Waltmann
- Institute for Global Health and Infectious Disease, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Tyler R McKinnish
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St Louis, Missouri
| | - Joseph A Duncan
- Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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12
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Wojnarski M, Lon C, Vanachayangkul P, Gosi P, Sok S, Rachmat A, Harrison D, Berjohn CM, Spring M, Chaoratanakawee S, Ittiverakul M, Buathong N, Chann S, Wongarunkochakorn S, Waltmann A, Kuntawunginn W, Fukuda MM, Burkly H, Heang V, Heng TK, Kong N, Boonchan T, Chum B, Smith P, Vaughn A, Prom S, Lin J, Lek D, Saunders D. Atovaquone-Proguanil in Combination With Artesunate to Treat Multidrug-Resistant P. falciparum Malaria in Cambodia: An Open-Label Randomized Trial. Open Forum Infect Dis 2019; 6:ofz314. [PMID: 31660398 DOI: 10.1093/ofid/ofz314] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 06/28/2019] [Indexed: 12/16/2022] Open
Abstract
Background Recent artemisinin-combination therapy failures in Cambodia prompted a search for alternatives. Atovaquone-proguanil (AP), a safe, effective treatment for multidrug-resistant Plasmodium falciparum (P.f.), previously demonstrated additive effects in combination with artesunate (AS). Methods Patients with P.f. or mixed-species infection (n = 205) in Anlong Veng (AV; n = 157) and Kratie (KT; n = 48), Cambodia, were randomized open-label 1:1 to a fixed-dose 3-day AP regimen +/-3 days of co-administered artesunate (ASAP). Single low-dose primaquine (PQ, 15 mg) was given on day 1 to prevent gametocyte-mediated transmission. Results Polymerase chain reaction-adjusted adequate clinical and parasitological response at 42 days was 90% for AP (95% confidence interval [CI], 82%-95%) and 92% for ASAP (95% CI, 83%-96%; P = .73). The median parasite clearance time was 72 hours for ASAP in AV vs 56 hours in KT (P < .001) and was no different than AP alone. At 1 week postprimaquine, 7% of the ASAP group carried microscopic gametocytes vs 29% for AP alone (P = .0001). Nearly all P.f. isolates had C580Y K13 propeller artemisinin resistance mutations (AV 99%; KT 88%). Only 1 of 14 treatment failures carried the cytochrome bc1 (Pfcytb) atovaquone resistance mutation, which was not present at baseline. P.f. isolates remained atovaquone sensitive in vitro but cycloguanil resistant, with a triple P.f. dihydrofolate reductase mutation. Conclusions Atovaquone-proguanil remained marginally effective in Cambodia (≥90%) with minimal Pfcytb mutations observed. Treatment failures in the presence of ex vivo atovaquone sensitivity and adequate plasma levels may be attributable to cycloguanil and/or artemisinin resistance. Artesunate co-administration provided little additional blood-stage efficacy but reduced post-treatment gametocyte carriage in combination with AP beyond single low-dose primaquine.
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Affiliation(s)
- Mariusz Wojnarski
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Chanthap Lon
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | | | - Panita Gosi
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Somethy Sok
- Department of Health, Ministry of National Defense, Phnom Penh, Cambodia
| | - Agus Rachmat
- Naval Medical Research Unit-2, Phnom Penh, Cambodia
| | | | | | - Michele Spring
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.,Henry M. Jackson Foundation, Bethesda, Maryland
| | - Suwanna Chaoratanakawee
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.,Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Mali Ittiverakul
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Nillawan Buathong
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Soklyda Chann
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | | | | | | | - Mark M Fukuda
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Hana Burkly
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Vireak Heang
- Naval Medical Research Unit-2, Phnom Penh, Cambodia
| | - Thay Keang Heng
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Nareth Kong
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Threechada Boonchan
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - Bolin Chum
- Naval Medical Research Unit-2, Phnom Penh, Cambodia
| | - Philip Smith
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | | | - Satharath Prom
- Department of Health, Ministry of National Defense, Phnom Penh, Cambodia
| | - Jessica Lin
- Division of Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina
| | - Dysoley Lek
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - David Saunders
- US Army Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.,US Army Medical Materiel Development Activity, Fort Detrick, Maryland
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13
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Waltmann A, Willcox AC, Balasubramanian S, Borrini Mayori K, Mendoza Guerrero S, Salazar Sanchez RS, Roach J, Condori Pino C, Gilman RH, Bern C, Juliano JJ, Levy MZ, Meshnick SR, Bowman NM. Hindgut microbiota in laboratory-reared and wild Triatoma infestans. PLoS Negl Trop Dis 2019; 13:e0007383. [PMID: 31059501 PMCID: PMC6522061 DOI: 10.1371/journal.pntd.0007383] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 05/16/2019] [Accepted: 04/10/2019] [Indexed: 12/14/2022] Open
Abstract
Triatomine vectors transmit Trypanosoma cruzi, the etiological agent of Chagas disease in humans. Transmission to humans typically occurs when contaminated triatomine feces come in contact with the bite site or mucosal membranes. In the Southern Cone of South America, where the highest burden of disease exists, Triatoma infestans is the principal vector for T. cruzi. Recent studies of other vector-borne illnesses have shown that arthropod microbiota influences the ability of infectious agents to colonize the insect vector and transmit to the human host. This has garnered attention as a potential control strategy against T. cruzi, as vector control is the main tool of Chagas disease prevention. Here we characterized the microbiota in T. infestans feces of both wild-caught and laboratory-reared insects and examined the relationship between microbial composition and T. cruzi infection using highly sensitive high-throughput sequencing technology to sequence the V3-V4 region of the 16S ribosomal RNA gene on the MiSeq Illumina platform. We collected 59 wild (9 with T. cruzi infection) and 10 lab-reared T. infestans (4 with T. cruzi infection) from the endemic area of Arequipa, Perú. Wild T. infestans had greater hindgut bacterial diversity than laboratory-reared bugs. Microbiota of lab insects comprised a subset of those identified in their wild counterparts, with 96 of the total 124 genera also observed in laboratory-reared insects. Among wild insects, variation in bacterial composition was observed, but time and location of collection and development stage did not explain this variation. T. cruzi infection in lab insects did not affect α- or β-diversity; however, we did find that the β-diversity of wild insects differed if they were infected with T. cruzi and identified 10 specific taxa that had significantly different relative abundances in infected vs. uninfected wild T. infestans (Bosea, Mesorhizobium, Dietzia, and Cupriavidus were underrepresented in infected bugs; Sporosarcina, an unclassified genus of Porphyromonadaceae, Nestenrenkonia, Alkalibacterium, Peptoniphilus, Marinilactibacillus were overrepresented in infected bugs). Our findings suggest that T. cruzi infection is associated with the microbiota of T. infestans and that inferring the microbiota of wild T. infestans may not be possible through sampling of T. infestans reared in the insectary. Chagas disease in humans is caused by the parasite Trypanosoma cruzi and it is endemic to the Americas. Poor populations are most at risk. The parasite infects an estimated six million people of 21 endemic countries in the Americas, with 30,000 new infections yearly. The main mode of transmission is vector-borne by triatomine bugs, which tend to live in close association with humans. The main Chagas disease vector in the Southern Cone of South America, where the highest burden of disease exists, is Triatoma infestans. As blood-sucking insects, triatomines become infected when they bite a T. cruzi-positive human and once infected they transmit the parasites in their feces. Controlling the vector populations is the main strategy of Chagas disease transmission reduction efforts. Microbiota-mediated methods to control this vector-borne disease are now being explored to determine whether microbes typically found in the vectors’ gut have a detrimental effect on T. cruzi and how they may be used to modify the vector and curb the ability for T. cruzi to be transmitted to humans. To advance this new field, we first must gain better knowledge of the gut microbiota of triatomines. Our study is the first to use sensitive high-throughput methods to study the gut microbes of T. infestans, using both laboratory-reared and wild insects. We have found that the microbial composition of T. infestans in the laboratory does not reflect the complete collection of gut microbes of wild T. infestans and inferring the gut microbiota profile of wild insects through studying lab insects alone may not be possible. We also found evidence that in wild insects T. cruzi affects the composition of the gut microbiota and identified some bacterial taxa which may be important in modulating the T.infestans-T.cruzi relationship.
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Affiliation(s)
- Andreea Waltmann
- Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
| | - Alexandra C. Willcox
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sujata Balasubramanian
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Katty Borrini Mayori
- Zoonotic Disease Research Laboratory, Unidad de Una Salud, Universidad Peruana Cayetano Heredia, Arequipa, Perú
| | - Sandra Mendoza Guerrero
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Renzo S. Salazar Sanchez
- Zoonotic Disease Research Laboratory, Unidad de Una Salud, Universidad Peruana Cayetano Heredia, Arequipa, Perú
| | - Jeffrey Roach
- Microbiome Core Facility, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Carlos Condori Pino
- Zoonotic Disease Research Laboratory, Unidad de Una Salud, Universidad Peruana Cayetano Heredia, Arequipa, Perú
| | - Robert H. Gilman
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Caryn Bern
- Department of Epidemiology and Biostatistics, School of Medicine, University of California-San Francisco, San Francisco, California, United States of America
| | - Jonathan J. Juliano
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Michael Z. Levy
- Department of Biostatistics, Epidemiology & Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Steven R. Meshnick
- Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Natalie M. Bowman
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
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14
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Quah YW, Waltmann A, Karl S, White MT, Vahi V, Darcy A, Pitakaka F, Whittaker M, Tisch DJ, Barry A, Barnadas C, Kazura J, Mueller I. Molecular epidemiology of residual Plasmodium vivax transmission in a paediatric cohort in Solomon Islands. Malar J 2019; 18:106. [PMID: 30922304 PMCID: PMC6437916 DOI: 10.1186/s12936-019-2727-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 03/14/2019] [Indexed: 01/03/2023] Open
Abstract
Background Following the scale-up of intervention efforts, malaria burden has decreased dramatically in Solomon Islands (SI). Submicroscopic and asymptomatic Plasmodium vivax infections are now the major challenge for malaria elimination in this country. Since children have higher risk of contracting malaria, this study investigated the dynamics of Plasmodium spp. infections among children including the associated risk factors of residual P. vivax burden. Methods An observational cohort study was conducted among 860 children aged 0.5–12 years in Ngella (Central Islands Province, SI). Children were monitored by active and passive surveillances for Plasmodium spp. infections and illness. Parasites were detected by quantitative real-time PCR (qPCR) and genotyped. Comprehensive statistical analyses of P. vivax infection prevalence, molecular force of blood stage infection (molFOB) and infection density were conducted. Results Plasmodium vivax infections were common (overall prevalence: 11.9%), whereas Plasmodium falciparum infections were rare (0.3%) but persistent. Although children acquire an average of 1.1 genetically distinct P. vivax blood-stage infections per year, there was significant geographic heterogeneity in the risks of P. vivax infections across Ngella (prevalence: 1.2–47.4%, p < 0.01; molFOB: 0.05–4.6/year, p < 0.01). Malaria incidence was low (IR: 0.05 episodes/year-at-risk). Age and measures of high exposure were the key risk factors for P. vivax infections and disease. Malaria incidence and infection density decreased with age, indicating significant acquisition of immunity. G6PD deficient children (10.8%) that did not receive primaquine treatment had a significantly higher prevalence (aOR: 1.77, p = 0.01) and increased risk of acquiring new bloodstage infections (molFOB aIRR: 1.51, p = 0.03), underscoring the importance of anti-relapse treatment. Conclusion Residual malaria transmission in Ngella exhibits strong heterogeneity and is characterized by a high proportion of submicroscopic and asymptomatic P. vivax infections, alongside sporadic P. falciparum infections. Implementing an appropriate primaquine treatment policy to prevent P. vivax relapses and specific targeting of control interventions to high risk areas will be required to accelerate ongoing control and elimination activities. Electronic supplementary material The online version of this article (10.1186/s12936-019-2727-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yi Wan Quah
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Andreea Waltmann
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Stephan Karl
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Michael T White
- Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Ventis Vahi
- National Health Training & Research Institute, Ministry of Health, Honiara, Solomon Islands
| | - Andrew Darcy
- National Health Training & Research Institute, Ministry of Health, Honiara, Solomon Islands
| | - Freda Pitakaka
- National Health Training & Research Institute, Ministry of Health, Honiara, Solomon Islands
| | - Maxine Whittaker
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia
| | | | - Alyssa Barry
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Celine Barnadas
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia.,Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia
| | - James Kazura
- Case Western Reserve University, Cleveland, OH, USA
| | - Ivo Mueller
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia. .,Department of Medical Biology, The University of Melbourne, Parkville, VIC, Australia. .,Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.
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15
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Waltmann A, Patel JC, Thwai KL, Hathaway NJ, Parobek CM, Massougbodji A, Fievet N, Bailey JA, Deloron P, Juliano JJ, Ndam NT, Meshnick SR. Matched Placental and Circulating Plasmodium falciparum Parasites are Genetically Homologous at the var2csa ID1-DBL2X Locus by Deep Sequencing. Am J Trop Med Hyg 2018; 98:77-82. [PMID: 29342401 DOI: 10.4269/ajtmh.17-0529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In pregnancy-associated malaria, infected erythrocytes accumulate in the placenta. It is unclear if in polyclonal infections this results in distinct peripheral and placental parasite populations. We used long amplicon deep sequencing of Plasmodium falciparum var2csa ID1-DBL2X from 15 matched peripheral and placental samples collected at delivery from a high transmission area to determine genetic homology. Despite substantial sequence variation and detecting 23 haplotypes, the matched pairs mostly contained the same genetic variants, with 11 pairs sharing 100% of their variants, whereas others showed some heterogeneity. Thus, at delivery, peripheral and placental parasites appear to intermix and placental genotypes can be inferred through peripheral sampling.
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Affiliation(s)
- Andreea Waltmann
- Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
| | - Jaymin C Patel
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
| | - Kyaw L Thwai
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
| | - Nicholas J Hathaway
- Program in Bioinformatics and Integrative Biology, University of Massachusetts, Worcester, Massachusetts
| | - Christian M Parobek
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina
| | - Achille Massougbodji
- Centre d'Etude et de Recherche sur le paludisme associé à la Grossesse et à l'Enfance, Université d'Abomey-Calavi, Cotonou, Benin
| | - Nadine Fievet
- UMR216 - MERIT, Institut de Recherche pour le Développement, COMUE Sorbonne Paris Cité, Université Paris Descartes, Paris, France
| | - Jeffery A Bailey
- Division of Transfusion Medicine, Department of Medicine, University of Massachusetts, Worcester, Massachusetts.,Program in Bioinformatics and Integrative Biology, University of Massachusetts, Worcester, Massachusetts
| | - Philippe Deloron
- UMR216 - MERIT, Institut de Recherche pour le Développement, COMUE Sorbonne Paris Cité, Université Paris Descartes, Paris, France
| | - Jonathan J Juliano
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina.,Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina.,Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
| | - Nicaise Tuikue Ndam
- UMR216 - MERIT, Institut de Recherche pour le Développement, COMUE Sorbonne Paris Cité, Université Paris Descartes, Paris, France
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina.,Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
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16
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Koepfli C, Waltmann A, Ome-Kaius M, Robinson LJ, Mueller I. Multiplicity of Infection Is a Poor Predictor of Village-Level Plasmodium vivax and P. falciparum Population Prevalence in the Southwest Pacific. Open Forum Infect Dis 2018; 5:ofy240. [PMID: 30397622 PMCID: PMC6210381 DOI: 10.1093/ofid/ofy240] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 09/18/2018] [Indexed: 12/31/2022] Open
Abstract
Across 8101 individuals in 46 villages, the proportion of Plasmodium spp. multiple clone infections (0%–53.8%) did not reflect prevalence by quantitative polymerase chain reaction (qPCR; 1.9%–38.4%), except for P. vivax in Solomon Islands (P < .001). Thus this parameter was not informative to identify transmission foci. In contrast, prevalence by microscopy and qPCR correlated well.
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Affiliation(s)
- Cristian Koepfli
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia.,University of Notre Dame, Department of Biological Sciences, Eck Institute for Global Health, Notre Dame, USA
| | - Andreea Waltmann
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Maria Ome-Kaius
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia.,Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Leanne J Robinson
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia.,Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea.,Burnet Institute, Melbourne, Australia
| | - Ivo Mueller
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Australia.,Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
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17
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White MT, Walker P, Karl S, Hetzel MW, Freeman T, Waltmann A, Laman M, Robinson LJ, Ghani A, Mueller I. Mathematical modelling of the impact of expanding levels of malaria control interventions on Plasmodium vivax. Nat Commun 2018; 9:3300. [PMID: 30120250 PMCID: PMC6097992 DOI: 10.1038/s41467-018-05860-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Accepted: 07/23/2018] [Indexed: 01/07/2023] Open
Abstract
Plasmodium vivax poses unique challenges for malaria control and elimination, notably the potential for relapses to maintain transmission in the face of drug-based treatment and vector control strategies. We developed an individual-based mathematical model of P. vivax transmission calibrated to epidemiological data from Papua New Guinea (PNG). In many settings in PNG, increasing bed net coverage is predicted to reduce transmission to less than 0.1% prevalence by light microscopy, however there is substantial risk of rebounds in transmission if interventions are removed prematurely. In several high transmission settings, model simulations predict that combinations of existing interventions are not sufficient to interrupt P. vivax transmission. This analysis highlights the potential options for the future of P. vivax control: maintaining existing public health gains by keeping transmission suppressed through indefinite distribution of interventions; or continued development of strategies based on existing and new interventions to push for further reduction and towards elimination.
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Affiliation(s)
- Michael T White
- Malaria: Parasites and Hosts, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Dr Roux, 75015, Paris, France.
| | - Patrick Walker
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, Norfolk Place, W2 1PG, UK
| | - Stephan Karl
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang 511, Papua New Guinea
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, Melbourne University, Melbourne, VIC, 3052, Australia
| | - Manuel W Hetzel
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | - Tim Freeman
- Rotarians Against Malaria, Port Moresby 121, Papua New Guinea
| | - Andreea Waltmann
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, Melbourne University, Melbourne, VIC, 3052, Australia
| | - Moses Laman
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang 511, Papua New Guinea
| | - Leanne J Robinson
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang 511, Papua New Guinea
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, Melbourne University, Melbourne, VIC, 3052, Australia
- Burnet Institute, Melbourne, VIC, 3004, Australia
| | - Azra Ghani
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, Norfolk Place, W2 1PG, UK
| | - Ivo Mueller
- Malaria: Parasites and Hosts, Department of Parasites and Insect Vectors, Institut Pasteur, 25-28 Rue du Dr Roux, 75015, Paris, France
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Melbourne, VIC, 3052, Australia
- Department of Medical Biology, Melbourne University, Melbourne, VIC, 3052, Australia
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18
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Boyce RM, Hathaway N, Fulton T, Reyes R, Matte M, Ntaro M, Mulogo E, Waltmann A, Bailey JA, Siedner MJ, Juliano JJ. Reuse of malaria rapid diagnostic tests for amplicon deep sequencing to estimate Plasmodium falciparum transmission intensity in western Uganda. Sci Rep 2018; 8:10159. [PMID: 29977002 PMCID: PMC6033881 DOI: 10.1038/s41598-018-28534-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 06/25/2018] [Indexed: 01/29/2023] Open
Abstract
Molecular techniques are not routinely employed for malaria surveillance, while cross-sectional, community-based parasite surveys require significant resources. Here, we describe a novel use of malaria rapid diagnostic tests (RDTs) collected at a single facility as source material for sequencing to esimtate malaria transmission intensity across a relatively large catchment area. We extracted Plasmodium falciparum DNA from RDTs, then amplified and sequenced a region of the apical membrane antigen 1 (pfama1) using targeted amplicon deep sequencing. We determined the multiplicity of infection (MOI) for each sample and examined associations with demographic, clinical, and spatial factors. We successfully genotyped 223 of 287 (77.7%) of the samples. We demonstrated an inverse relationship between the MOI and elevation with individuals presenting from the highest elevation villages harboring infections approximately half as complex as those from the lowest (MOI 1.85 vs. 3.51, AOR 0.25, 95% CI 0.09-0.65, p = 0.004). This study demonstrates the feasibility and validity of using routinely-collected RDTs for molecular surveillance of malaria and has real-world utility, especially as the cost of high-throughpout sequencing continues to decline.
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Affiliation(s)
- Ross M Boyce
- Division of Infectious Diseases, University of North Carolina at Chapel Hill, 130 Mason Farm Road, Chapel Hill, 27599, USA.
| | - Nick Hathaway
- Program in Bioinformatics and Integrative Biology, University of Massachusetts, 368 Plantation St., Worcester, Massachusetts, 01605, USA
| | - Travis Fulton
- Division of Epidemiology, University of North Carolina at Chapel Hill Gillings School of Global Public Health, 135 Dauer Drive, Chapel Hill, 27599, USA
| | - Raquel Reyes
- Division of General Medicine & Clinical Epidemiology, University of North Carolina at Chapel Hill, 5039 Old Clinic Building, CB 7110, Chapel Hill, 27599, USA
| | - Michael Matte
- Department of Community Health, Mbarara University of Science & Technology, P.O. Box 1410, Mbarara, Uganda
| | - Moses Ntaro
- Department of Community Health, Mbarara University of Science & Technology, P.O. Box 1410, Mbarara, Uganda
| | - Edgar Mulogo
- Department of Community Health, Mbarara University of Science & Technology, P.O. Box 1410, Mbarara, Uganda
| | - Andreea Waltmann
- Division of Infectious Diseases, University of North Carolina at Chapel Hill, 130 Mason Farm Road, Chapel Hill, 27599, USA
| | - Jeffrey A Bailey
- Program in Bioinformatics and Integrative Biology, University of Massachusetts, 368 Plantation St., Worcester, Massachusetts, 01605, USA
| | - Mark J Siedner
- Department of Medicine, Harvard Medical School and Massachusetts General Hospital, 125 Nashua Street, Suite 722, Boston, 02114, USA
| | - Jonathan J Juliano
- Division of Infectious Diseases, University of North Carolina at Chapel Hill, 130 Mason Farm Road, Chapel Hill, 27599, USA.,Division of Epidemiology, University of North Carolina at Chapel Hill Gillings School of Global Public Health, 135 Dauer Drive, Chapel Hill, 27599, USA.,Curriculum in Genetics and Microbiology, University of North Carolina at Chapel Hill, 321 South Columbia Street, Chapel Hill, NC, 27516, USA
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19
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Verity R, Hathaway NJ, Waltmann A, Doctor SM, Watson OJ, Patel JC, Mwandagalirwa K, Tshefu AK, Bailey JA, Ghani AC, Juliano JJ, Meshnick SR. Plasmodium falciparum genetic variation of var2csa in the Democratic Republic of the Congo. Malar J 2018; 17:46. [PMID: 29361940 PMCID: PMC5782373 DOI: 10.1186/s12936-018-2193-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/17/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Democratic Republic of the Congo (DRC) bears a high burden of malaria, which is exacerbated in pregnant women. The VAR2CSA protein plays a crucial role in pregnancy-associated malaria (PAM), and hence quantifying diversity at the var2csa locus in the DRC is important in understanding the basic epidemiology of PAM, and in developing a robust vaccine against PAM. METHODS Samples were taken from the 2013-14 Demographic and Health Survey conducted in the DRC, focusing on children under 5 years of age. A short subregion of the var2csa gene was sequenced in 115 spatial clusters, giving country-wide estimates of sequence polymorphism and spatial population structure. RESULTS Results indicate that var2csa is highly polymorphic, and that diversity is being maintained through balancing selection, however, there is no clear signal of phylogenetic or geographic structure to this diversity. Linear modelling demonstrates that the number of var2csa variants in a cluster correlates directly with cluster prevalence, but not with other epidemiological factors such as urbanicity. CONCLUSIONS Results suggest that the DRC fits within the global pattern of high var2csa diversity and little genetic differentiation between regions. A broad multivalent VAR2CSA vaccine candidate could benefit from targeting stable regions and common variants to address the substantial genetic diversity.
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Affiliation(s)
- Robert Verity
- Medical Research Council Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Nicholas J Hathaway
- Program in Bioinformatics and Integrative Biology, University of Massachusetts, Worcester, MA, USA
- Division of Transfusion Medicine, Department of Medicine, University of Massachusetts, Worcester, MA, USA
| | - Andreea Waltmann
- Institute for Global Health and Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Stephanie M Doctor
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Oliver J Watson
- Medical Research Council Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Jaymin C Patel
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, USA
| | - Kashamuka Mwandagalirwa
- Kinshasa School of Public Health, Hôpital General Provincial de Reference de Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Antoinette K Tshefu
- Community Health, Kinshasa School of Public Health, School of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Jeffrey A Bailey
- Program in Bioinformatics and Integrative Biology, University of Massachusetts, Worcester, MA, USA
- Division of Transfusion Medicine, Department of Medicine, University of Massachusetts, Worcester, MA, USA
| | - Azra C Ghani
- Medical Research Council Centre for Outbreak Analysis & Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Jonathan J Juliano
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, USA
- Division of Infectious Diseases, University of North Carolina at Chapel Hill, 130 Mason Farm Road, Chapel Hill, 27599, USA
- Curriculum in Genetics and Microbiology, University of North Carolina at Chapel Hill, 321 South Columbia Street, Chapel Hill, NC, 27516, USA
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, USA
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20
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Hofmann NE, Karl S, Wampfler R, Kiniboro B, Teliki A, Iga J, Waltmann A, Betuela I, Felger I, Robinson LJ, Mueller I. The complex relationship of exposure to new Plasmodium infections and incidence of clinical malaria in Papua New Guinea. eLife 2017; 6:23708. [PMID: 28862132 PMCID: PMC5606846 DOI: 10.7554/elife.23708] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 08/18/2017] [Indexed: 01/20/2023] Open
Abstract
The molecular force of blood-stage infection (molFOB) is a quantitative surrogate metric for malaria transmission at population level and for exposure at individual level. Relationships between molFOB, parasite prevalence and clinical incidence were assessed in a treatment-to-reinfection cohort, where P.vivax (Pv) hypnozoites were eliminated in half the children by primaquine (PQ). Discounting relapses, children acquired equal numbers of new P. falciparum (Pf) and Pv blood-stage infections/year (Pf-molFOB = 0–18, Pv-molFOB = 0–23) resulting in comparable spatial and temporal patterns in incidence and prevalence of infections. Including relapses, Pv-molFOB increased >3 fold (relative to PQ-treated children) showing greater heterogeneity at individual (Pv-molFOB = 0–36) and village levels. Pf- and Pv-molFOB were strongly associated with clinical episode risk. Yearly Pf clinical incidence rate (IR = 0.28) was higher than for Pv (IR = 0.12) despite lower Pf-molFOB. These relationships between molFOB, clinical incidence and parasite prevalence reveal a comparable decline in Pf and Pv transmission that is normally hidden by the high burden of Pv relapses. Clinical trial registration: ClinicalTrials.gov NCT02143934 Malaria is caused by five different species of parasites that are transmitted to humans by bites from parasite-carrying mosquitos. Once in human blood, the parasites rapidly multiply. People who live in countries where malaria is common may become infected and never show any symptoms because their immune systems are able to keep parasite numbers low. Repeated infections, or infection with more than one species of malaria parasite also are common. Some species of malaria, including Plasmodium vivax, can hibernate in the liver for weeks or months after the infection and only become active later. Asymptomatic infections, multi-parasite infections, and reactivating parasites make it hard to measure how often new malaria infections occur. One way scientists can determine if a new infection has occurred is by genotyping the parasites in a person’s blood. Genotyping involves looking for small differences in the parasite DNA. For example, a study in Papua New Guinea, where P. vivax is very common, showed that reactivations of hibernating parasites were more common than new infections. Now, Hofmann et al. use the same study in Papua New Guinea to compare the frequency and consequences of new infections with P. vivax and another malaria parasite, Plasmodium falciparum. In the study, 466 children from 6 villages were followed for 8 months with tests every 2 to 4 weeks to genotype the parasites in their blood. Some of the children were treated with antimalarial drugs to help wipe out any existing parasites including hibernating ones. While P. vivax was about twice as common in blood samples—likely due to reactivation—genotyping showed that new infections with the two parasites occur at equal rates and often at the same times and locations. Hofmann et al. also showed that some villages and some children had much higher rates of infection than others. This difference could not fully be explained by use of bednets or other preventive measures. Children were more likely to become ill from P. falciparum than P. vivax even though P. vivax was more common. But children with more frequent infections with P. falciparum seemed better able to manage the parasites and were less likely to develop symptoms that those with infrequent infections. The experiments show that genotyping may help scientists better track new malaria infections and develop better strategies to prevent or treat malaria.
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Affiliation(s)
- Natalie E Hofmann
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Stephan Karl
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Rahel Wampfler
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Benson Kiniboro
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Albina Teliki
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Jonah Iga
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Andreea Waltmann
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,University of Melbourne, Melbourne, Australia
| | - Inoni Betuela
- Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Leanne J Robinson
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea.,University of Melbourne, Melbourne, Australia.,Burnet Institute, Melbourne, Australia
| | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,University of Melbourne, Melbourne, Australia.,ISGlobal, Barcelona Centre for International Health Research, Hospital Clínic-University of Barcelona, Barcelona, Spain.,Institut Pasteur, Paris, France
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21
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França CT, Hostetler JB, Sharma S, White MT, Lin E, Kiniboro B, Waltmann A, Darcy AW, Li Wai Suen CSN, Siba P, King CL, Rayner JC, Fairhurst RM, Mueller I. An Antibody Screen of a Plasmodium vivax Antigen Library Identifies Novel Merozoite Proteins Associated with Clinical Protection. PLoS Negl Trop Dis 2016; 10:e0004639. [PMID: 27182597 PMCID: PMC4868274 DOI: 10.1371/journal.pntd.0004639] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 03/29/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Elimination of Plasmodium vivax malaria would be greatly facilitated by the development of an effective vaccine. A comprehensive and systematic characterization of antibodies to P. vivax antigens in exposed populations is useful in guiding rational vaccine design. METHODOLOGY/PRINCIPAL FINDINGS In this study, we investigated antibodies to a large library of P. vivax entire ectodomain merozoite proteins in 2 Asia-Pacific populations, analysing the relationship of antibody levels with markers of current and cumulative malaria exposure, and socioeconomic and clinical indicators. 29 antigenic targets of natural immunity were identified. Of these, 12 highly-immunogenic proteins were strongly associated with age and thus cumulative lifetime exposure in Solomon Islanders (P<0.001-0.027). A subset of 6 proteins, selected on the basis of immunogenicity and expression levels, were used to examine antibody levels in plasma samples from a population of young Papua New Guinean children with well-characterized individual differences in exposure. This analysis identified a strong association between reduced risk of clinical disease and antibody levels to P12, P41, and a novel hypothetical protein that has not previously been studied, PVX_081550 (IRR 0.46-0.74; P<0.001-0.041). CONCLUSION/SIGNIFICANCE These data emphasize the benefits of an unbiased screening approach in identifying novel vaccine candidate antigens. Functional studies are now required to establish whether PVX_081550 is a key component of the naturally-acquired protective immune response, a biomarker of immune status, or both.
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Affiliation(s)
- Camila T. França
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Jessica B. Hostetler
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Sumana Sharma
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
| | - Michael T. White
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Center for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Enmoore Lin
- Vector Borne Diseases Unit, PNG Institute of Medical Research, Madang, Papua New Guinea
| | - Benson Kiniboro
- Vector Borne Diseases Unit, PNG Institute of Medical Research, Madang, Papua New Guinea
| | - Andreea Waltmann
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Andrew W. Darcy
- National Health Training & Research Institute, Ministry of Health, Honiara, Solomon Islands
| | - Connie S. N. Li Wai Suen
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Peter Siba
- Vector Borne Diseases Unit, PNG Institute of Medical Research, Madang, Papua New Guinea
| | - Christopher L. King
- Center for Global Health & Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Julian C. Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Hinxton, United Kingdom
- * E-mail: (JCR); (RMF); (IM)
| | - Rick M. Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (JCR); (RMF); (IM)
| | - Ivo Mueller
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
- * E-mail: (JCR); (RMF); (IM)
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22
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Waltmann A, Karl S, Chiu C, Mueller I. Limited Degradation of the Plasmodium falciparum Gametocyte Marker pfs25 mRNA Exposed to Tropical Temperatures: Considerations for Malaria Transmission Field Studies. Am J Trop Med Hyg 2016; 94:886-9. [PMID: 26856913 DOI: 10.4269/ajtmh.15-0531] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 11/17/2015] [Indexed: 12/27/2022] Open
Abstract
An important aspect of many malaria molecular epidemiology and transmission studies is RNA-based detection of gametocytes. Ensuring RNA stability represents a challenge in tropical, resource-limited environments, as RNA may quickly degrade when samples are not preserved under adequate conditions. This study investigated the degradation of pfs25 messenger RNA (mRNA), the most widely used Plasmodium falciparum gametocyte marker, in whole blood spiked with cultured P. falciparum gametocytes, exposed to different temperatures for up to 48 hours, and collected with different anticoagulants. The levels of pfs25 mRNA were similar between samples stored at 4°C and 30°C for up to 48 hours before stabilization with RNAprotect (Qiagen, Hilden, Germany). We observed that pfs25 mRNA in heparin-collected blood degraded less than that in ethylenediaminetetraacetic acid (EDTA)-collected blood over the 48-hour period. For field studies aiming for P. falciparum gametocyte detection, immediate stabilization of blood samples is not necessary, as the pfs25 transcript is relatively stable, more so in heparin than EDTA collection tubes.
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Affiliation(s)
- Andreea Waltmann
- The Walter and Eliza Hall Institute of Medical Research, Victoria, Australia; Department of Medical Biology, University of Melbourne, Victoria, Australia; Center de Recerca en Salut Internacional de Barcelona, Barcelona, Spain
| | - Stephan Karl
- The Walter and Eliza Hall Institute of Medical Research, Victoria, Australia; Department of Medical Biology, University of Melbourne, Victoria, Australia; Center de Recerca en Salut Internacional de Barcelona, Barcelona, Spain
| | - Chris Chiu
- The Walter and Eliza Hall Institute of Medical Research, Victoria, Australia; Department of Medical Biology, University of Melbourne, Victoria, Australia; Center de Recerca en Salut Internacional de Barcelona, Barcelona, Spain
| | - Ivo Mueller
- The Walter and Eliza Hall Institute of Medical Research, Victoria, Australia; Department of Medical Biology, University of Melbourne, Victoria, Australia; Center de Recerca en Salut Internacional de Barcelona, Barcelona, Spain
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23
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Robinson LJ, Wampfler R, Betuela I, Karl S, White MT, Li Wai Suen CSN, Hofmann NE, Kinboro B, Waltmann A, Brewster J, Lorry L, Tarongka N, Samol L, Silkey M, Bassat Q, Siba PM, Schofield L, Felger I, Mueller I. Strategies for understanding and reducing the Plasmodium vivax and Plasmodium ovale hypnozoite reservoir in Papua New Guinean children: a randomised placebo-controlled trial and mathematical model. PLoS Med 2015; 12:e1001891. [PMID: 26505753 PMCID: PMC4624431 DOI: 10.1371/journal.pmed.1001891] [Citation(s) in RCA: 180] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 09/17/2015] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND The undetectable hypnozoite reservoir for relapsing Plasmodium vivax and P. ovale malarias presents a major challenge for malaria control and elimination in endemic countries. This study aims to directly determine the contribution of relapses to the burden of P. vivax and P. ovale infection, illness, and transmission in Papua New Guinean children. METHODS AND FINDINGS From 17 August 2009 to 20 May 2010, 524 children aged 5-10 y from East Sepik Province in Papua New Guinea (PNG) participated in a randomised double-blind placebo-controlled trial of blood- plus liver-stage drugs (chloroquine [CQ], 3 d; artemether-lumefantrine [AL], 3 d; and primaquine [PQ], 20 d, 10 mg/kg total dose) (261 children) or blood-stage drugs only (CQ, 3 d; AL, 3 d; and placebo [PL], 20 d) (263 children). Participants, study staff, and investigators were blinded to the treatment allocation. Twenty children were excluded during the treatment phase (PQ arm: 14, PL arm: 6), and 504 were followed actively for 9 mo. During the follow-up time, 18 children (PQ arm: 7, PL arm: 11) were lost to follow-up. Main primary and secondary outcome measures were time to first P. vivax infection (by qPCR), time to first clinical episode, force of infection, gametocyte positivity, and time to first P. ovale infection (by PCR). A basic stochastic transmission model was developed to estimate the potential effect of mass drug administration (MDA) for the prevention of recurrent P. vivax infections. Targeting hypnozoites through PQ treatment reduced the risk of having at least one qPCR-detectable P. vivax or P. ovale infection during 8 mo of follow-up (P. vivax: PQ arm 0.63/y versus PL arm 2.62/y, HR = 0.18 [95% CI 0.14, 0.25], p < 0.001; P. ovale: 0.06 versus 0.14, HR = 0.31 [95% CI 0.13, 0.77], p = 0.011) and the risk of having at least one clinical P. vivax episode (HR = 0.25 [95% CI 0.11, 0.61], p = 0.002). PQ also reduced the molecular force of P. vivax blood-stage infection in the first 3 mo of follow-up (PQ arm 1.90/y versus PL arm 7.75/y, incidence rate ratio [IRR] = 0.21 [95% CI 0.15, 0.28], p < 0.001). Children who received PQ were less likely to carry P. vivax gametocytes (IRR = 0.27 [95% CI 0.19, 0.38], p < 0.001). PQ had a comparable effect irrespective of the presence of P. vivax blood-stage infection at the time of treatment (p = 0.14). Modelling revealed that mass screening and treatment with highly sensitive quantitative real-time PCR, or MDA with blood-stage treatment alone, would have only a transient effect on P. vivax transmission levels, while MDA that includes liver-stage treatment is predicted to be a highly effective strategy for P. vivax elimination. The inclusion of a directly observed 20-d treatment regime maximises the efficiency of hypnozoite clearance but limits the generalisability of results to real-world MDA programmes. CONCLUSIONS These results suggest that relapses cause approximately four of every five P. vivax infections and at least three of every five P. ovale infections in PNG children and are important in sustaining transmission. MDA campaigns combining blood- and liver-stage treatment are predicted to be a highly efficacious intervention for reducing P. vivax and P. ovale transmission. TRIAL REGISTRATION ClinicalTrials.gov NCT02143934.
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Affiliation(s)
- Leanne J. Robinson
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang and Maprik, Papua New Guinea
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Rahel Wampfler
- Molecular Diagnostics Unit, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Inoni Betuela
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang and Maprik, Papua New Guinea
| | - Stephan Karl
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Michael T. White
- MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, United Kingdom
| | - Connie S. N. Li Wai Suen
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Natalie E. Hofmann
- Molecular Diagnostics Unit, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Benson Kinboro
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang and Maprik, Papua New Guinea
| | - Andreea Waltmann
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Jessica Brewster
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Lina Lorry
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang and Maprik, Papua New Guinea
| | - Nandao Tarongka
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang and Maprik, Papua New Guinea
| | - Lornah Samol
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang and Maprik, Papua New Guinea
| | - Mariabeth Silkey
- Molecular Diagnostics Unit, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Quique Bassat
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - Peter M. Siba
- Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang and Maprik, Papua New Guinea
- School of Veterinary and Biomedical Sciences, James Cook University, Townsville, Queensland, Australia
| | - Louis Schofield
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - Ingrid Felger
- Molecular Diagnostics Unit, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Ivo Mueller
- Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic–University of Barcelona, Barcelona, Spain
- * E-mail:
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Barry AE, Waltmann A, Koepfli C, Barnadas C, Mueller I. Uncovering the transmission dynamics of Plasmodium vivax using population genetics. Pathog Glob Health 2015; 109:142-52. [PMID: 25891915 DOI: 10.1179/2047773215y.0000000012] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Population genetic analysis of malaria parasites has the power to reveal key insights into malaria epidemiology and transmission dynamics with the potential to deliver tools to support control and elimination efforts. Analyses of parasite genetic diversity have suggested that Plasmodium vivax populations are more genetically diverse and less structured than those of Plasmodium falciparum indicating that P. vivax may be a more ancient parasite of humans and/or less susceptible to population bottlenecks, as well as more efficient at disseminating its genes. These population genetic insights into P. vivax transmission dynamics provide an explanation for its relative resilience to control efforts. Here, we describe current knowledge on P. vivax population genetic structure, its relevance to understanding transmission patterns and relapse and how this information can inform malaria control and elimination programmes.
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Key Words
- Control,
- Elimination
- Genetic diversity,
- Genetics,
- Genomics,
- Linkage disequilibrium,
- Malaria,
- Microsatellites,
- Mitochondrial DNA,
- Plasmodium vivax,
- Population structure,
- Relapse,
- Single nucleotide polymorphisms,
- Transmission,
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25
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Karunajeewa H, Waltmann A, Wini L, Mueller I. Missing malaria? Potential obstacles to diagnosis and hypnozoite eradication. Med J Aust 2015; 202:360. [DOI: 10.5694/mja14.01760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 02/11/2015] [Indexed: 11/17/2022]
Affiliation(s)
- Harin Karunajeewa
- Walter and Eliza Hall Institute, Melbourne, VIC
- Western Health, Melbourne, VIC
| | | | - Lyndes Wini
- Ministry of Health, Honiara, Solomon Islands
| | - Ivo Mueller
- Walter and Eliza Hall Institute, Melbourne, VIC
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Wampfler R, Robinson L, Hofmann N, Waltmann A, Betuela I, Silkey M, Siba P, Smith T, Mueller I, Felger I. Dynamics of P. vivax clones in a cohort of children with or without primaquine treatment at baseline. Malar J 2014. [PMCID: PMC4179237 DOI: 10.1186/1475-2875-13-s1-o24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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27
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Karl S, Laman M, Koleala T, Ibam C, Kasian B, N'Drewei N, Rosanas-Urgell A, Moore BR, Waltmann A, Koepfli C, Siba PM, Betuela I, Woodward RC, St Pierre TG, Mueller I, Davis TME. Comparison of three methods for detection of gametocytes in Melanesian children treated for uncomplicated malaria. Malar J 2014; 13:319. [PMID: 25123055 PMCID: PMC4139605 DOI: 10.1186/1475-2875-13-319] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Accepted: 08/08/2014] [Indexed: 01/22/2023] Open
Abstract
Background Gametocytes are the transmission stages of Plasmodium parasites, the causative agents of malaria. As their density in the human host is typically low, they are often undetected by conventional light microscopy. Furthermore, application of RNA-based molecular detection methods for gametocyte detection remains challenging in remote field settings. In the present study, a detailed comparison of three methods, namely light microscopy, magnetic fractionation and reverse transcriptase polymerase chain reaction for detection of Plasmodium falciparum and Plasmodium vivax gametocytes was conducted. Methods Peripheral blood samples from 70 children aged 0.5 to five years with uncomplicated malaria who were treated with either artemether-lumefantrine or artemisinin-naphthoquine were collected from two health facilities on the north coast of Papua New Guinea. The samples were taken prior to treatment (day 0) and at pre-specified intervals during follow-up. Gametocytes were measured in each sample by three methods: i) light microscopy (LM), ii) quantitative magnetic fractionation (MF) and, iii) reverse transcriptase PCR (RTPCR). Data were analysed using censored linear regression and Bland and Altman techniques. Results MF and RTPCR were similarly sensitive and specific, and both were superior to LM. Overall, there were approximately 20% gametocyte-positive samples by LM, whereas gametocyte positivity by MF and RTPCR were both more than two-fold this level. In the subset of samples collected prior to treatment, 29% of children were positive by LM, and 85% were gametocyte positive by MF and RTPCR, respectively. Conclusions The present study represents the first direct comparison of standard LM, MF and RTPCR for gametocyte detection in field isolates. It provides strong evidence that MF is superior to LM and can be used to detect gametocytaemic patients under field conditions with similar sensitivity and specificity as RTPCR. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-319) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stephan Karl
- School of Medicine and Pharmacology, University of Western Australia, Fremantle Hospital, Fremantle, Western Australia, Australia.
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