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Markwalter CF, Lapp Z, Abel L, Kimachas E, Omollo E, Freedman E, Chepkwony T, Amunga M, McCormick T, Bérubé S, Mangeni JN, Wesolowski A, Obala AA, Taylor SM, Prudhomme O'Meara W. Plasmodium falciparum infection in humans and mosquitoes influence natural Anopheline biting behavior and transmission. Nat Commun 2024; 15:4626. [PMID: 38816383 PMCID: PMC11139876 DOI: 10.1038/s41467-024-49080-9] [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: 02/20/2024] [Accepted: 05/22/2024] [Indexed: 06/01/2024] Open
Abstract
The human infectious reservoir of Plasmodium falciparum is governed by transmission efficiency during vector-human contact and mosquito biting preferences. Understanding biting bias in a natural setting can help target interventions to interrupt transmission. In a 15-month cohort in western Kenya, we detected P. falciparum in indoor-resting Anopheles and human blood samples by qPCR and matched mosquito bloodmeals to cohort participants using short-tandem repeat genotyping. Using risk factor analyses and discrete choice models, we assessed mosquito biting behavior with respect to parasite transmission. Biting was highly unequal; 20% of people received 86% of bites. Biting rates were higher on males (biting rate ratio (BRR): 1.68; CI: 1.28-2.19), children 5-15 years (BRR: 1.49; CI: 1.13-1.98), and P. falciparum-infected individuals (BRR: 1.25; CI: 1.01-1.55). In aggregate, P. falciparum-infected school-age (5-15 years) boys accounted for 50% of bites potentially leading to onward transmission and had an entomological inoculation rate 6.4x higher than any other group. Additionally, infectious mosquitoes were nearly 3x more likely than non-infectious mosquitoes to bite P. falciparum-infected individuals (relative risk ratio 2.76, 95% CI 1.65-4.61). Thus, persistent P. falciparum transmission was characterized by disproportionate onward transmission from school-age boys and by the preference of infected mosquitoes to feed upon infected people.
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Affiliation(s)
| | - Zena Lapp
- Duke Global Health Institute, Duke University, Durham, NC, USA
| | - Lucy Abel
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret, Kenya
| | - Emmah Kimachas
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret, Kenya
| | | | - Elizabeth Freedman
- Division of Infectious Diseases, Duke University School of Medicine, Durham, NC, USA
| | - Tabitha Chepkwony
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret, Kenya
| | - Mark Amunga
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret, Kenya
| | - Tyler McCormick
- Departments of Statistics & Sociology, University of Washington, Seattle, WA, USA
| | - Sophie Bérubé
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Judith N Mangeni
- School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Amy Wesolowski
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Andrew A Obala
- School of Medicine, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Steve M Taylor
- Duke Global Health Institute, Duke University, Durham, NC, USA.
- Division of Infectious Diseases, Duke University School of Medicine, Durham, NC, USA.
| | - Wendy Prudhomme O'Meara
- Duke Global Health Institute, Duke University, Durham, NC, USA.
- Division of Infectious Diseases, Duke University School of Medicine, Durham, NC, USA.
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Friedman-Klabanoff DJ, Adu-Gyasi D, Asante KP. Malaria prevention in children: an update. Curr Opin Pediatr 2024; 36:164-170. [PMID: 38299986 PMCID: PMC10932812 DOI: 10.1097/mop.0000000000001332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
PURPOSE OF REVIEW Malaria cases and deaths decreased from 2000 to 2015 but remain increased since 2019. Several new developments and strategies could help reverse this trend. The purpose of this review is to discuss new World Health Organization (WHO) guidelines and recent research on malaria prevention in children. RECENT FINDINGS Fifteen countries have now rolled out seasonal malaria chemoprophylaxis (SMC) in children at highest risk for severe malaria, and new WHO recommendations provide more flexibility for SMC implementation in terms of target age groups, geographic region, and number of cycles. Recent studies confirm that malaria burden in school aged children, and their contribution to transmission, is high. New guidelines permit expanded chemoprevention options for these children. Two vaccines have been approved for use in malaria endemic countries, RTS,S/AS01 E and R21/Matrix-M. Additionally, pyrethroid-chlorfenapyr bed nets are being deployed to combat resistant mosquitoes. SUMMARY While challenges remain in malaria control towards elimination, new guidelines and recently approved vaccines offer hope. Monitoring for continued vaccine and chemoprevention effectiveness, and for possible epidemiologic shifts in severe malaria presentation and deaths as additional prevention efforts roll out will be paramount.
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Affiliation(s)
- DeAnna J Friedman-Klabanoff
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Dennis Adu-Gyasi
- Kintampo Health Research Centre, Research and Development Division, Ghana Health Service, Kintampo North Municipality, Bono East Region, Ghana
- Centre for Research in Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana, West Africa
| | - Kwaku Poku Asante
- Kintampo Health Research Centre, Research and Development Division, Ghana Health Service, Kintampo North Municipality, Bono East Region, Ghana
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Lapp Z, Abel L, Mangeni J, Obala AA, O'Meara W, Taylor SM, Markwalter CF. bistro: An R package for vector bloodmeal identification by short tandem repeat overlap. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.09.14.23295566. [PMID: 37745593 PMCID: PMC10516083 DOI: 10.1101/2023.09.14.23295566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
1. Measuring vector-human contact in a natural setting can inform precise targeting of interventions to interrupt transmission of vector-borne diseases. One approach is to directly match human DNA in vector bloodmeals to the individuals who were bitten using genotype panels of discriminative short tandem repeats (STRs). Existing methods for matching STR profiles in bloodmeals to the people bitten preclude the ability to match most incomplete profiles and multi-source bloodmeals to bitten individuals. 2. We developed bistro, an R package that implements 3 preexisting STR matching methods as well as the package's namesake, bistro, a new algorithm described here. bistro employs forensic analysis methods to calculate likelihood ratios and match human STR profiles in bloodmeals to people using a dynamic threshold. We evaluated the algorithm's accuracy and compared it to existing matching approaches using a publicly-available panel of 188 single-source and 100 multi-source samples containing DNA from 50 known human sources. Then we applied it to match 777 newly field-collected mosquito bloodmeals to a database of 645 people. 3. The R package implements four STR matching algorithms in user-friendly functions with clear documentation. bistro correctly matched 99% (184/185) of profiles in single-source samples, and 63% (225/359) of profiles from multi-source samples, resulting in a sensitivity of 0.75 (vs < 0.51 for other algorithms). The specificity of bistro was 0.9998 (vs. 1 for other algorithms). Furthermore, bistro identified 80% (729/909) of all possible matches for field-derived mosquitoes, yielding 1.4x more matches than existing algorithms. 4. bistro identifies more correct bloodmeal-human matches than existing approaches, enabling more accurate and robust analyses of vector-human contact in natural settings. The bistro R package and corresponding documentation allow for straightforward uptake of this algorithm by others.
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Affiliation(s)
- Zena Lapp
- Duke Global Health Institute, Duke University, Durham, NC, USA
| | - Lucy Abel
- Academic Model Providing Access to Healthcare (AMPATH), Eldoret, Kenya
| | - Judith Mangeni
- Department of Epidemiology and Medical Statistics, School of Public Health, Moi University, Eldoret, Kenya
| | - Andrew A Obala
- School of Medicine, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Wendy O'Meara
- Duke Global Health Institute, Duke University, Durham, NC, USA
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, NC, USA
| | - Steve M Taylor
- Duke Global Health Institute, Duke University, Durham, NC, USA
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, NC, USA
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