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Rapp T, Amagai K, Sinai C, Basham C, Loya M, Ngasala S, Said H, Muller MS, Chhetri SB, Yang G, François R, Odas M, Mathias D, Juliano JJ, Lin FC, Ngasala B, Lin JT. Microheterogeneity of Transmission Shapes Submicroscopic Malaria Carriage in Coastal Tanzania. J Infect Dis 2024; 230:485-496. [PMID: 38781438 PMCID: PMC11326843 DOI: 10.1093/infdis/jiae276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 04/14/2024] [Accepted: 05/21/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Asymptomatic carriage of malaria parasites persists even as malaria transmission declines. Low-density infections are often submicroscopic, not detected with rapid diagnostic tests (RDTs) or microscopy but detectable by polymerase chain reaction (PCR). METHODS To characterize submicroscopic Plasmodium falciparum carriage in an area of declining malaria transmission, asymptomatic persons >5 years of age in rural Bagamoyo District, Tanzania, were screened using RDT, microscopy, and PCR. We investigated the size of the submicroscopic reservoir of infection across villages, determined factors associated with submicroscopic carriage, and assessed the natural history of submicroscopic malaria over 4 weeks. RESULTS Among 6076 participants, P. falciparum prevalences by RDT, microscopy, and PCR were 9%, 9%, and 28%, respectively, with roughly two-thirds of PCR-positive individuals harboring submicroscopic infection. Adult status, female sex, dry season months, screened windows, and bed net use were associated with submicroscopic carriage. Among 15 villages encompassing 80% of participants, the proportion of submicroscopic carriers increased with decreasing village-level malaria prevalence. Over 4 weeks, 23% of submicroscopic carriers (61 of 266) became RDT positive, with half exhibiting symptoms, while half (133 of 266) were no longer parasitemic at the end of 4 weeks. Progression to RDT-positive patent malaria occurred more frequently in villages with higher malaria prevalence. CONCLUSIONS Microheterogeneity in transmission observed at the village level appears to affect both the size of the submicroscopic reservoir and the likelihood of submicroscopic carriers developing patent malaria in coastal Tanzania.
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Affiliation(s)
- Tyler Rapp
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Kano Amagai
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Cyrus Sinai
- Department of Geography, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Christopher Basham
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Mwajabu Loya
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Sifa Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Hamza Said
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Meredith S Muller
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Srijana B Chhetri
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Guozheng Yang
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Ruthly François
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Melic Odas
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Derrick Mathias
- Florida Medical Entomology Laboratory, Institute of Food & Agricultural Sciences, University of Florida, Vero Beach, Florida, USA
| | - Jonathan J Juliano
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Feng-Chang Lin
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Billy Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Jessica T Lin
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
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2
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Prah DA, Laryea-Akrong E. Asymptomatic Low-Density Plasmodium falciparum Infections: Parasites Under the Host's Immune Radar? J Infect Dis 2024; 229:1913-1918. [PMID: 38349649 PMCID: PMC11175676 DOI: 10.1093/infdis/jiad581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 12/18/2023] [Indexed: 06/15/2024] Open
Abstract
A large body of evidence suggests that low parasite carriage in Plasmodium falciparum asymptomatic infection is required for the maintenance of malaria immunity. However, the fact that treating such infections has little to no impact on subsequent clinical malaria is rarely noted. In this paper, we review data and argue that low-density parasite carriage in asymptomatic infection may not support host immune processes and that parasites are virtually under the host's immunological radar. We also discuss factors that may be constraining parasitemia in asymptomatic infections from reaching the threshold required to cause clinical symptoms. A thorough understanding of this infectious reservoir is essential for malaria control and eradication because asymptomatic infections contribute significantly to Plasmodium transmission.
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Affiliation(s)
- Diana Ahu Prah
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana
- Faculty of Applied Sciences, Department of Science Laboratory Technology, Accra Technical University, Accra, Ghana
| | - Elizabeth Laryea-Akrong
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Legon, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
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Zeno EE, Obala AA, Pence B, Freedman E, Mangeni JN, Lin JT, Abel L, Edwards JK, Gower EW, Taylor SM. Risk of Malaria Following Untreated Subpatent Plasmodium falciparum Infections: Results Over 4 Years From a Cohort in a High-Transmission Area in Western Kenya. J Infect Dis 2024; 229:969-978. [PMID: 37713614 PMCID: PMC11011184 DOI: 10.1093/infdis/jiad398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 08/30/2023] [Accepted: 09/11/2023] [Indexed: 09/17/2023] Open
Abstract
BACKGROUND People with suspected malaria may harbor Plasmodium falciparum undetected by rapid diagnostic test (RDT). The impact of these subpatent infections on the risk of developing clinical malaria is not fully understood. METHODS We analyzed subpatent P. falciparum infections using a longitudinal cohort in a high-transmission site in Kenya. Weighted Kaplan-Meier models estimated the risk difference (RD) for clinical malaria during the 60 days following a symptomatic subpatent infection. Stratum-specific estimates by age and transmission season assessed modification. RESULTS Over 54 months, we observed 1128 symptomatic RDT-negative suspected malaria episodes, of which 400 (35.5%) harbored subpatent P. falciparum. Overall, the 60-day risk of developing clinical malaria was low following all episodes (8.6% [95% confidence interval, 6.7%-10.4%]). In the low-transmission season, the risk of clinical malaria was slightly higher in those with subpatent infection, whereas the opposite was true in the high-transmission season (low-transmission season RD, 2.3% [95% confidence interval, .4%-4.2%]; high-transmission season RD, -4.8% [-9.5% to -.05%]). CONCLUSIONS The risk of developing clinical malaria among people with undetected subpatent infections is low. A slightly elevated risk in the low-transmission season may merit alternate management, but RDTs identify clinically relevant infections in the high-transmission season.
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Affiliation(s)
- Erica E Zeno
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, USA
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, USA
| | - Andrew A Obala
- School of Medicine, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Brian Pence
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, USA
| | - Elizabeth Freedman
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, USA
| | - Judith N Mangeni
- School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Jessica T Lin
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, USA
| | - Lucy Abel
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret, Kenya
| | - Jessie K Edwards
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, USA
| | - Emily W Gower
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, USA
| | - Steve M Taylor
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, USA
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
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Rapp T, Amagai K, Sinai C, Basham C, Loya M, Ngasala S, Said H, Muller MS, Chhetri SB, Yang G, François R, Odas M, Mathias D, Juliano JJ, Lin FC, Ngasala B, Lin JT. Micro-heterogeneity of transmission shapes the submicroscopic malaria reservoir in coastal Tanzania. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.09.06.23295089. [PMID: 37732257 PMCID: PMC10508794 DOI: 10.1101/2023.09.06.23295089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Background Asymptomatic malaria may be patent (visible by microscopy) and detectable by rapid malaria diagnostic tests (RDTs), or it may be submicroscopic and only detectable by polymerase chain reaction (PCR). Methods To characterize the submicroscopic reservoir in an area of declining malaria transmission, asymptomatic persons >5 years of age in Bagamoyo District, Tanzania, were screened using RDT, microscopy, and PCR. We investigated the size of the submicroscopic reservoir across villages, determined factors associated with submicroscopic parasitemia, and assessed the natural history of submicroscopic malaria over four weeks. Results Among 6,076 participants, Plasmodium falciparum prevalence by RDT, microscopy, and PCR was 9%, 9%, and 28%, respectively, with roughly two-thirds of PCR-positive individuals harboring submicroscopic infection. Adult status, female gender, dry season months, screened windows, and bednet use were associated with submicroscopic carriage. Among 15 villages encompassing 80% of participants, the proportion of submicroscopic carriers increased with decreasing village-level malaria prevalence. Over four weeks, 23% (61/266) of submicroscopic carriers became RDT-positive and were treated, with half exhibiting symptoms. This occurred more frequently in villages with higher malaria prevalence. Conclusions Micro-heterogeneity in transmission impacts the size of the submicroscopic reservoir and the likelihood of submicroscopic carriers developing patent malaria in coastal Tanzania.
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Affiliation(s)
- Tyler Rapp
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Kano Amagai
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Cyrus Sinai
- Department of Geography, University of North Carolina, Chapel Hill, NC USA
| | - Christopher Basham
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Mwajabu Loya
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Sifa Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Hamza Said
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Meredith S Muller
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Srijana B Chhetri
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Guozheng Yang
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Ruthly François
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Melic Odas
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Derrick Mathias
- Florida Medical Entomology Laboratory, Institute of Food & Agricultural Sciences, University of Florida, Vero Beach, FL USA
| | - Jonathan J Juliano
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Feng-Chang Lin
- Department of Geography, University of North Carolina, Chapel Hill, NC USA
| | - Billy Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Jessica T Lin
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
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Biabi MFAB, Fogang B, Essangui E, Maloba F, Donkeu C, Keumoe R, Cheteug G, Magoudjou N, Slam C, Kemleu S, Efange N, Perraut R, Nsango SE, Eboumbou Moukoko CE, Assam JPA, Etoa FX, Lamb T, Ayong L. High Prevalence of Polyclonal Plasmodium falciparum Infections and Association with Poor IgG Antibody Responses in a Hyper-Endemic Area in Cameroon. Trop Med Infect Dis 2023; 8:390. [PMID: 37624328 PMCID: PMC10459087 DOI: 10.3390/tropicalmed8080390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 08/26/2023] Open
Abstract
Malaria remains a major public health problem worldwide, with eradication efforts thwarted by drug and insecticide resistance and the lack of a broadly effective malaria vaccine. In continuously exposed communities, polyclonal infections are thought to reduce the risk of severe disease and promote the establishment of asymptomatic infections. We sought to investigate the relationship between the complexity of P. falciparum infection and underlying host adaptive immune responses in an area with a high prevalence of asymptomatic parasitaemia in Cameroon. A cross-sectional study of 353 individuals aged 2 to 86 years (median age = 16 years) was conducted in five villages in the Centre Region of Cameroon. Plasmodium falciparum infection was detected by multiplex nested PCR in 316 samples, of which 278 were successfully genotyped. Of these, 60.1% (167/278) were polyclonal infections, the majority (80.2%) of which were from asymptomatic carriers. Host-parasite factors associated with polyclonal infection in the study population included peripheral blood parasite density, participant age and village of residence. The number of parasite clones per infected sample increased significantly with parasite density (r = 0.3912, p < 0.0001) but decreased with participant age (r = -0.4860, p < 0.0001). Parasitaemia and the number of clones per sample correlated negatively with total plasma levels of IgG antibodies to three highly reactive P. falciparum antigens (MSP-1p19, MSP-3 and EBA175) and two soluble antigen extracts (merozoite and mixed stage antigens). Surprisingly, we observed no association between the frequency of polyclonal infection and susceptibility to clinical disease as assessed by the recent occurrence of malarial symptoms or duration since the previous fever episode. Overall, the data indicate that in areas with the high perennial transmission of P. falciparum, parasite polyclonality is dependent on underlying host antibody responses, with the majority of polyclonal infections occurring in persons with low levels of protective anti-plasmodial antibodies.
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Affiliation(s)
- Marie Florence A Bite Biabi
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biochemistry, Faculty of Science, University of Douala, Douala BP 2701, Cameroon
| | - Balotin Fogang
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon
| | - Estelle Essangui
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala BP 2701, Cameroon
| | - Franklin Maloba
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
| | - Christiane Donkeu
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon
| | - Rodrigue Keumoe
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biochemistry, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon
| | - Glwadys Cheteug
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Medical Laboratory Sciences, Faculty of Science, University of Buea, Buea BP 63, Cameroon
| | - Nina Magoudjou
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biochemistry, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon
| | - Celine Slam
- Department of Pathology, School of Medicine, University of Utah, 15 N Medical Drive, Salt Lake City, UT 84112, USA;
| | - Sylvie Kemleu
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
| | - Noella Efange
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biochemistry, Faculty of Science, University of Buea, Buea BP 63, Cameroon
| | - Ronald Perraut
- Centre Pasteur du Cameroun Annex, Garoua BP 921, Cameroon;
| | - Sandrine Eveline Nsango
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala BP 2701, Cameroon
| | - Carole Else Eboumbou Moukoko
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala BP 2701, Cameroon
| | - Jean Paul Assam Assam
- Department of Microbiology, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon; (J.P.A.A.); (F.-X.E.)
| | - François-Xavier Etoa
- Department of Microbiology, Faculty of Science, University of Yaounde I, Yaounde BP 812, Cameroon; (J.P.A.A.); (F.-X.E.)
| | - Tracey Lamb
- Department of Pathology, School of Medicine, University of Utah, 15 N Medical Drive, Salt Lake City, UT 84112, USA;
| | - Lawrence Ayong
- Malaria Research Unit, Centre Pasteur du Cameroun, Yaounde BP 1274, Cameroon; (M.F.A.B.B.); (B.F.); (E.E.); (F.M.); (C.D.); (R.K.); (G.C.); (N.M.); (S.K.); (N.E.); (S.E.N.); (C.E.E.M.)
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6
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Markwalter CF, Petersen JEV, Zeno EE, Sumner KM, Freedman E, Mangeni JN, Abel L, Obala AA, Prudhomme-O’Meara W, Taylor SM. Symptomatic malaria enhances protection from reinfection with homologous Plasmodium falciparum parasites. PLoS Pathog 2023; 19:e1011442. [PMID: 37307293 PMCID: PMC10289385 DOI: 10.1371/journal.ppat.1011442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 06/23/2023] [Accepted: 05/24/2023] [Indexed: 06/14/2023] Open
Abstract
A signature remains elusive of naturally-acquired immunity against Plasmodium falciparum. We identified P. falciparum in a 14-month cohort of 239 people in Kenya, genotyped at immunogenic parasite targets expressed in the pre-erythrocytic (circumsporozoite protein, CSP) and blood (apical membrane antigen 1, AMA-1) stages, and classified into epitope type based on variants in the DV10, Th2R, and Th3R epitopes in CSP and the c1L region of AMA-1. Compared to asymptomatic index infections, symptomatic malaria was associated with reduced reinfection by parasites bearing homologous CSP-Th2R (adjusted hazard ratio [aHR]:0.63; 95% CI:0.45-0.89; p = 0.008) CSP-Th3R (aHR:0.71; 95% CI:0.52-0.97; p = 0.033), and AMA-1 c1L (aHR:0.63; 95% CI:0.43-0.94; p = 0.022) epitope types. The association of symptomatic malaria with reduced hazard of homologous reinfection was strongest for rare epitope types. Symptomatic malaria provides more durable protection against reinfection with parasites bearing homologous epitope types. The phenotype represents a legible molecular epidemiologic signature of naturally-acquired immunity by which to identify new antigen targets.
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Affiliation(s)
- Christine F. Markwalter
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
| | - Jens E. V. Petersen
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, United States of America
| | - Erica E. Zeno
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, United States of America
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Kelsey M. Sumner
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, United States of America
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Elizabeth Freedman
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, United States of America
| | - Judith N. Mangeni
- School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Lucy Abel
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret, Kenya
| | - Andrew A. Obala
- School of Medicine, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Wendy Prudhomme-O’Meara
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, United States of America
- School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Steve M. Taylor
- Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, North Carolina, United States of America
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
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7
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Arambepola R, Bérubé S, Freedman B, Taylor SM, Prudhomme O’Meara W, Obala AA, Wesolowski A. Exploring how space, time, and sampling impact our ability to measure genetic structure across Plasmodium falciparum populations. FRONTIERS IN EPIDEMIOLOGY 2023; 3:1058871. [PMID: 38516334 PMCID: PMC10956351 DOI: 10.3389/fepid.2023.1058871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 01/18/2023] [Indexed: 03/23/2024]
Abstract
A primary use of malaria parasite genomics is identifying highly related infections to quantify epidemiological, spatial, or temporal factors associated with patterns of transmission. For example, spatial clustering of highly related parasites can indicate foci of transmission and temporal differences in relatedness can serve as evidence for changes in transmission over time. However, for infections in settings of moderate to high endemicity, understanding patterns of relatedness is compromised by complex infections, overall high forces of infection, and a highly diverse parasite population. It is not clear how much these factors limit the utility of using genomic data to better understand transmission in these settings. In particular, further investigation is required to determine which patterns of relatedness we expect to see with high quality, densely sampled genomic data in a high transmission setting and how these observations change under different study designs, missingness, and biases in sample collection. Here we investigate two identity-by-state measures of relatedness and apply them to amplicon deep sequencing data collected as part of a longitudinal cohort in Western Kenya that has previously been analysed to identify individual-factors associated with sharing parasites with infected mosquitoes. With these data we use permutation tests, to evaluate several hypotheses about spatiotemporal patterns of relatedness compared to a null distribution. We observe evidence of temporal structure, but not of fine-scale spatial structure in the cohort data. To explore factors associated with the lack of spatial structure in these data, we construct a series of simplified simulation scenarios using an agent based model calibrated to entomological, epidemiological and genomic data from this cohort study to investigate whether the lack of spatial structure observed in the cohort could be due to inherent power limitations of this analytical method. We further investigate how our hypothesis testing behaves under different sampling schemes, levels of completely random and systematic missingness, and different transmission intensities.
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Affiliation(s)
- Rohan Arambepola
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Batlimore, MD, United States
| | - Sophie Bérubé
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Batlimore, MD, United States
| | - Betsy Freedman
- Division of Infectious Diseases, Duke University Medical Center, Durham, NC, United States
| | - Steve M. Taylor
- Division of Infectious Diseases, Duke University Medical Center, Durham, NC, United States
- Duke Global Health Institute, Durham, NC, United States
| | - Wendy Prudhomme O’Meara
- Division of Infectious Diseases, Duke University Medical Center, Durham, NC, United States
- Duke Global Health Institute, Durham, NC, United States
| | | | - Amy Wesolowski
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Batlimore, MD, United States
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8
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Markwalter CF, Petersen JEV, Zeno EE, Sumner KM, Freedman E, Mangeni JN, Abel L, Obala AA, Prudhomme-O’Meara W, Taylor SM. Symptomatic malaria enhances protection from reinfection with homologous Plasmodium falciparum parasites. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.01.04.23284198. [PMID: 36711685 PMCID: PMC9882554 DOI: 10.1101/2023.01.04.23284198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A signature remains elusive of naturally-acquired immunity against Plasmodium falciparum . We identified P. falciparum in a 14-month cohort of 239 people in Kenya, genotyped at immunogenic parasite targets expressed in the pre-erythrocytic (circumsporozoite protein, CSP) and blood (apical membrane antigen 1, AMA-1) stages, and classified into epitope type based on variants in the DV10, Th2R, and Th3R epitopes in CSP and the c1L region of AMA-1. Compared to asymptomatic index infections, symptomatic malaria was associated with a reduced reinfection by parasites bearing homologous CSP-Th2R (adjusted hazard ratio [aHR]:0.63; 95% CI:0.45-0.89; p=0.008) CSP-Th3R (aHR:0.71; 95% CI:0.52-0.97; p=0.033), and AMA-1 c1L (aHR:0.63; 95% CI:0.43-0.94; p=0.022) epitope types. The association of symptomatic malaria with reduced risk of homologous reinfection was strongest for rare epitope types. Symptomatic malaria more effectively promotes functional immune responses. The phenotype represents a legible molecular epidemiologic signature of naturally-acquired immunity by which to identify new antigen targets.
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Affiliation(s)
| | - Jens E. V. Petersen
- Division of Infectious Diseases, School of Medicine, Duke University, Durham NC USA
| | - Erica E. Zeno
- Division of Infectious Diseases, School of Medicine, Duke University, Durham NC USA,Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill NC USA
| | - Kelsey M. Sumner
- Division of Infectious Diseases, School of Medicine, Duke University, Durham NC USA,Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill NC USA
| | - Elizabeth Freedman
- Division of Infectious Diseases, School of Medicine, Duke University, Durham NC USA
| | - Judith N. Mangeni
- School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Lucy Abel
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret Kenya
| | - Andrew A. Obala
- School of Medicine, College of Health Sciences, Moi University, Eldoret Kenya
| | - Wendy Prudhomme-O’Meara
- Duke Global Health Institute, Duke University, Durham NC USA,Division of Infectious Diseases, School of Medicine, Duke University, Durham NC USA,School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Steve M. Taylor
- Duke Global Health Institute, Duke University, Durham NC USA,Division of Infectious Diseases, School of Medicine, Duke University, Durham NC USA,Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill NC USA,Corresponding author: Steve M Taylor ,
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9
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O'Flaherty K, Roe M, Fowkes FJ. The role of naturally acquired antimalarial antibodies in subclinical
Plasmodium
spp. infection. J Leukoc Biol 2022; 111:1097-1105. [PMID: 35060185 PMCID: PMC9303632 DOI: 10.1002/jlb.5mr1021-537r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 12/09/2021] [Indexed: 12/17/2022] Open
Affiliation(s)
- Katherine O'Flaherty
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
| | - Merryn Roe
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
- School of Public Health and Preventive Medicine Monash University Melbourne Australia
| | - Freya J.I. Fowkes
- Disease Elimination Program Burnet Institute for Medical Research and Public Health Melbourne Australia
- School of Public Health and Preventive Medicine Monash University Melbourne Australia
- Centre for Epidemiology and Biostatistics Melbourne School of Population and Global Health, The University of Melbourne Melbourne Australia
- Department of Infectious Disease Monash University Melbourne Australia
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10
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Sumner KM, Mangeni JN, Obala AA, Freedman E, Abel L, Meshnick SR, Edwards JK, Pence BW, Prudhomme-O'Meara W, Taylor SM. Impact of asymptomatic Plasmodium falciparum infection on the risk of subsequent symptomatic malaria in a longitudinal cohort in Kenya. eLife 2021; 10:e68812. [PMID: 34296998 PMCID: PMC8337072 DOI: 10.7554/elife.68812] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/20/2021] [Indexed: 11/13/2022] Open
Abstract
Background Asymptomatic Plasmodium falciparum infections are common in sub-Saharan Africa, but their effect on subsequent symptomaticity is incompletely understood. Methods In a 29-month cohort of 268 people in Western Kenya, we investigated the association between asymptomatic P. falciparum and subsequent symptomatic malaria with frailty Cox models. Results Compared to being uninfected, asymptomatic infections were associated with an increased 1 month likelihood of symptomatic malaria (adjusted hazard ratio [aHR]: 2.61, 95% CI: 2.05 to 3.33), and this association was modified by sex, with females (aHR: 3.71, 95% CI: 2.62 to 5.24) at higher risk for symptomaticity than males (aHR: 1.76, 95% CI: 1.24 to 2.50). This increased symptomatic malaria risk was observed for asymptomatic infections of all densities and in people of all ages. Long-term risk was attenuated but still present in children under age 5 (29-month aHR: 1.38, 95% CI: 1.05 to 1.81). Conclusions In this high-transmission setting, asymptomatic P. falciparum can be quickly followed by symptoms and may be targeted to reduce the incidence of symptomatic illness. Funding This work was supported by the National Institute of Allergy and Infectious Diseases (R21AI126024 to WPO, R01AI146849 to WPO and SMT).
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Affiliation(s)
- Kelsey M Sumner
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
- Division of Infectious Diseases, School of Medicine, Duke UniversityDurhamUnited States
| | - Judith N Mangeni
- School of Public Health, College of Health Sciences, Moi UniversityEldoretKenya
| | - Andrew A Obala
- School of Medicine, College of Health Sciences, Moi UniversityEldoretKenya
| | - Elizabeth Freedman
- Division of Infectious Diseases, School of Medicine, Duke UniversityDurhamUnited States
| | - Lucy Abel
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral HospitalEldoretKenya
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
| | - Jessie K Edwards
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
| | - Brian W Pence
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
| | - Wendy Prudhomme-O'Meara
- Division of Infectious Diseases, School of Medicine, Duke UniversityDurhamUnited States
- School of Public Health, College of Health Sciences, Moi UniversityEldoretKenya
- Duke Global Health Institute, Duke UniversityDurhamUnited States
| | - Steve M Taylor
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
- Division of Infectious Diseases, School of Medicine, Duke UniversityDurhamUnited States
- Duke Global Health Institute, Duke UniversityDurhamUnited States
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