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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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2
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Giraldo D, McMeniman CJ. Quantifying Mosquito Host Preference. Cold Spring Harb Protoc 2024; 2024:107663. [PMID: 37612146 DOI: 10.1101/pdb.top107663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
The most dangerous mosquito species for human health are those that blood feed preferentially and frequently on humans (anthropophilic mosquitoes). These include prolific disease vectors such as the African malaria mosquito Anopheles gambiae and yellow fever mosquito Aedes aegypti The chemosensory basis for anthropophilic behavior exhibited by these disease vectors, as well as the factors that drive interindividual differences in human attractiveness to mosquitoes, remain largely uncharacterized. Here, we concisely review established methods to quantify mosquito interspecific and intraspecific host preference in the laboratory, as well as semi-field and field environments. Experimental variables for investigator consideration during assays of mosquito host preference across these settings are highlighted.
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Affiliation(s)
- Diego Giraldo
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA
| | - Conor J McMeniman
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland 21205, USA
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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3
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Moreno M, Barry A, Gmeiner M, Yaro JB, Sermé SS, Byrne I, Ramjith J, Ouedraogo A, Soulama I, Grignard L, Soremekun S, Koele S, Ter Heine R, Ouedraogo AZ, Sawadogo J, Sanogo E, Ouedraogo IN, Hien D, Sirima SB, Bradley J, Bousema T, Drakeley C, Tiono AB. Understanding and maximising the community impact of seasonal malaria chemoprevention in Burkina Faso (INDIE-SMC): study protocol for a cluster randomised evaluation trial. BMJ Open 2024; 14:e081682. [PMID: 38479748 PMCID: PMC10936478 DOI: 10.1136/bmjopen-2023-081682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 02/19/2024] [Indexed: 03/26/2024] Open
Abstract
INTRODUCTION Seasonal malaria chemoprevention (SMC) involves repeated administrations of sulfadoxine-pyrimethamine plus amodiaquine to children below the age of 5 years during the peak transmission season in areas of seasonal malaria transmission. While highly impactful in reducing Plasmodium falciparum malaria burden in controlled research settings, the impact of SMC on infection prevalence is moderate in real-life settings. It remains unclear what drives this efficacy decay. Recently, the WHO widened the scope for SMC to target all vulnerable populations. The Ministry of Health (MoH) in Burkina Faso is considering extending SMC to children below 10 years old. We aim to assess the impact of SMC on clinical incidence and parasite prevalence and quantify the human infectious reservoir for malaria in this population. METHODS AND ANALYSIS We will perform a cluster randomised trial in Saponé Health District, Burkina Faso, with three study arms comprising 62 clusters of three compounds: arm 1 (control): SMC in under 5-year-old children, implemented by the MoH without directly observed treatment (DOT) for the full course of SMC; arm 2 (intervention): SMC in under 5-year-old children, with DOT for the full course of SMC; arm 3 (intervention): SMC in under 10-year-old children, with DOT for the full course of SMC. The primary endpoint is parasite prevalence at the end of the malaria transmission season. Secondary endpoints include the impact of SMC on clinical incidence. Factors affecting SMC uptake, treatment adherence, drug concentrations, parasite resistance markers and transmission of parasites will be determined. ETHICS AND DISSEMINATION The London School of Hygiene & Tropical Medicine's Ethics Committee (29193) and the Burkina Faso National Medical Ethics Committee (Deliberation No 2023-05-104) approved this study. The findings will be presented to the community; disease occurrence data and study outcomes will also be shared with the Burkina Faso MoH. Findings will be published irrespective of their results. TRIAL REGISTRATION NUMBER NCT05878366.
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Affiliation(s)
- Marta Moreno
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Aissata Barry
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Markus Gmeiner
- Department of Medical Microbiology, Radboud University Nijmegen, Nijmegen, The Netherlands
| | | | - Samuel S Sermé
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Isabel Byrne
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Jordache Ramjith
- Department of Medical Microbiology, Radboud University Nijmegen, Nijmegen, The Netherlands
| | | | - Issiaka Soulama
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Lynn Grignard
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Seyi Soremekun
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Simon Koele
- Department of Medical Microbiology, Radboud University Nijmegen, Nijmegen, The Netherlands
| | | | | | - Jean Sawadogo
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | - Edith Sanogo
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | | | - Denise Hien
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
| | | | - John Bradley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Alfred B Tiono
- Groupe de Recherche Action en Santé, Ouagadougou, Burkina Faso
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4
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Giraldo D, Rankin-Turner S, Corver A, Tauxe GM, Gao AL, Jackson DM, Simubali L, Book C, Stevenson JC, Thuma PE, McCoy RC, Gordus A, Mburu MM, Simulundu E, McMeniman CJ. Human scent guides mosquito thermotaxis and host selection under naturalistic conditions. Curr Biol 2023; 33:2367-2382.e7. [PMID: 37209680 PMCID: PMC10824255 DOI: 10.1016/j.cub.2023.04.050] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/23/2023] [Accepted: 04/21/2023] [Indexed: 05/22/2023]
Abstract
The African malaria mosquito Anopheles gambiae exhibits a strong innate drive to seek out humans in its sensory environment, classically entering homes to land on human skin in the hours flanking midnight. To gain insight into the role that olfactory cues emanating from the human body play in generating this epidemiologically important behavior, we developed a large-scale multi-choice preference assay in Zambia with infrared motion vision under semi-field conditions. We determined that An. gambiae prefers to land on arrayed visual targets warmed to human skin temperature during the nighttime when they are baited with carbon dioxide (CO2) emissions reflective of a large human over background air, body odor from one human over CO2, and the scent of one sleeping human over another. Applying integrative whole body volatilomics to multiple humans tested simultaneously in competition in a six-choice assay, we reveal high attractiveness is associated with whole body odor profiles from humans with increased relative abundances of the volatile carboxylic acids butyric acid, isobutryic acid, and isovaleric acid, and the skin microbe-generated methyl ketone acetoin. Conversely, those least preferred had whole body odor that was depleted of carboxylic acids among other compounds and enriched with the monoterpenoid eucalyptol. Across expansive spatial scales, heated targets without CO2 or whole body odor were minimally or not attractive at all to An. gambiae. These results indicate that human scent acts critically to guide thermotaxis and host selection by this prolific malaria vector as it navigates towards humans, yielding intrinsic heterogeneity in human biting risk.
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Affiliation(s)
- Diego Giraldo
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Stephanie Rankin-Turner
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Abel Corver
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Genevieve M Tauxe
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Anne L Gao
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Dorian M Jackson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | | | - Christopher Book
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA; Macha Research Trust, Choma District, PO Box 630166, Zambia
| | - Jennifer C Stevenson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA; Macha Research Trust, Choma District, PO Box 630166, Zambia
| | - Philip E Thuma
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA; Macha Research Trust, Choma District, PO Box 630166, Zambia
| | - Rajiv C McCoy
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Andrew Gordus
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | | | | | - Conor J McMeniman
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA; The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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5
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Coleman S, Yihdego Y, Gyamfi F, Kolyada L, Tongren JE, Zigirumugabe S, Dery DB, Badu K, Obiri-Danso K, Boakye D, Szumlas D, Armistead JS, Dadzie SK. Estimating malaria transmission risk through surveillance of human-vector interactions in northern Ghana. Parasit Vectors 2023; 16:205. [PMID: 37337221 DOI: 10.1186/s13071-023-05793-2] [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: 11/18/2022] [Accepted: 04/28/2023] [Indexed: 06/21/2023] Open
Abstract
BACKGROUND Vector bionomics are important aspects of vector-borne disease control programs. Mosquito-biting risks are affected by environmental, mosquito behavior and human factors, which are important for assessing exposure risk and intervention impacts. This study estimated malaria transmission risk based on vector-human interactions in northern Ghana, where indoor residual spraying (IRS) and insecticide-treated nets (ITNs) have been deployed. METHODS Indoor and outdoor human biting rates (HBRs) were measured using monthly human landing catches (HLCs) from June 2017 to April 2019. Mosquitoes collected were identified to species level, and Anopheles gambiae sensu lato (An. gambiae s.l.) samples were examined for parity and infectivity. The HBRs were adjusted using mosquito parity and human behavioral observations. RESULTS Anopheles gambiae was the main vector species in the IRS (81%) and control (83%) communities. Indoor and outdoor HBRs were similar in both the IRS intervention (10.6 vs. 11.3 bites per person per night [b/p/n]; z = -0.33, P = 0.745) and control communities (18.8 vs. 16.4 b/p/n; z = 1.57, P = 0.115). The mean proportion of parous An. gambiae s.l. was lower in IRS communities (44.6%) than in control communities (71.7%). After adjusting for human behavior observations and parity, the combined effect of IRS and ITN utilization (IRS: 37.8%; control: 57.3%) on reducing malaria transmission risk was 58% in IRS + ITN communities and 27% in control communities with ITNs alone (z = -4.07, P < 0.001). However, this also revealed that about 41% and 31% of outdoor adjusted bites in IRS and control communities respectively, occurred before bed time (10:00 pm). The mean directly measured annual entomologic inoculation rates (EIRs) during the study were 6.1 infective bites per person per year (ib/p/yr) for IRS communities and 16.3 ib/p/yr for control communities. After considering vector survival and observed human behavior, the estimated EIR for IRS communities was 1.8 ib/p/yr, which represents about a 70% overestimation of risk compared to the directly measured EIR; for control communities, it was 13.6 ib/p/yr (16% overestimation). CONCLUSION Indoor residual spraying significantly impacted entomological indicators of malaria transmission. The results of this study indicate that vector bionomics alone do not provide an accurate assessment of malaria transmission exposure risk. By accounting for human behavior parameters, we found that high coverage of ITNs alone had less impact on malaria transmission indices than combining ITNs with IRS, likely due to observed low net use. Reinforcing effective communication for behavioral change in net use and IRS could further reduce malaria transmission.
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Affiliation(s)
- Sylvester Coleman
- U.S. President's Malaria Initiative VectorLink Project, Accra, Ghana.
- Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Yemane Yihdego
- U.S. President's Malaria Initiative VectorLink Project, Accra, Ghana
| | - Frank Gyamfi
- U.S. President's Malaria Initiative VectorLink Project, Accra, Ghana
| | - Lena Kolyada
- U.S. President's Malaria Initiative VectorLink Project, Accra, Ghana
| | - Jon Eric Tongren
- U.S. President's Malaria Initiative, Malaria Branch, U.S. Centers for Disease Control and Prevention, Accra, Ghana
| | - Sixte Zigirumugabe
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Accra, Ghana
| | - Dominic B Dery
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Accra, Ghana
| | - Kingsley Badu
- Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | | | - Daniel Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
| | - Daniel Szumlas
- Armed Forces Pest Management Board, 172 Forney Road, Forest Glen Annex, Silver Spring, MD, 20910, USA
| | - Jennifer S Armistead
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA
| | - Samuel K Dadzie
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Accra, Ghana
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Ehrlich HY, Somé AF, Bazié T, Ebou CN, Dembélé EL, Balma R, Goodwin J, Wade M, Bei AK, Ouédraogo JB, Foy BD, Dabiré RK, Parikh S. Tracking antimalarial drug resistance using mosquito blood meals: a cross-sectional study. THE LANCET. MICROBE 2023; 4:e461-e469. [PMID: 37086737 PMCID: PMC10365133 DOI: 10.1016/s2666-5247(23)00063-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 04/24/2023]
Abstract
BACKGROUND Strong surveillance systems with wide geographic coverage are needed to detect and respond to reports of antimalarial drug resistance on the African continent. We aimed to assess the utility and feasibility of using blood-fed mosquitos (xenomonitoring) to conduct rapid surveillance of molecular markers associated with resistance in human populations. METHODS We conducted three cross-sectional surveys in two rainy seasons and the interim dry season in southwest Burkina Faso between Oct 10, 2018, and Sept 17, 2019. We collected human blood samples and blood-fed mosquitos residing in household clusters across seven village sectors. Samples were assessed for Plasmodium falciparum with ultrasensitive quantitative PCR, genotyped for two markers of reduced drug susceptibility, pfmdr1 256A>T (Asn86Tyr) and pfcrt 227A>C (Lys76Thr), and sequenced for four markers of clonality. We assessed statistical equivalence using a 10% margin of equivalence. FINDINGS We identified 551 infections in 1483 human blood samples (mean multiplicity of infection [MOI] 1·94, SD 1·47) and 346 infections in 2151 mosquito blood meals (mean MOI 2·2, SD 1·67). The frequency of pfmdr1 Asn86Tyr was 4% in survey 1, 2% in survey 2, and 12% in survey 3 in human samples, and 3% in survey 1, 0% in survey 2, and 8% in survey 3 in mosquito blood meals, and inter-host frequencies were statistically equivalent in surveys 1 and 2 (p<0·0001) but not Survey 3 (p=0·062) within a tolerability of 0·10. The frequency of pfcrt Lys76Thr was 16% in survey 1, 55% in survey 2, and 11% in survey 3 in humans and 40% in survey 1, 72% in survey 2, and 13% in survey 3 in mosquitos, and inter-host frequencies were equivalent in survey 3 only (p=0·032) within a tolerability of 0·10. In simulations, multiple but not preferential feeding behaviour in mosquitos reduced the accuracy of frequency estimates between hosts, particularly for markers circulating at higher frequencies. INTERPRETATION Molecular markers in mosquito blood meals and in humans exhibited similar temporal trends but frequencies were not statistically equivalent in all scenarios. More work is needed to determine empirical and pragmatic thresholds of difference. Xenomonitoring might be an efficient tool to provide rapid information on emerging antimalarial resistance in regions with insufficient surveillance. FUNDING National Institute of Allergy and Infectious Diseases. TRANSLATION For the French translation of the abstract see Supplementary Materials section.
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Affiliation(s)
- Hanna Y Ehrlich
- Department of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, USA; One Health Institute, University of California, Davis, CA, USA.
| | - A Fabrice Somé
- Department of Parasitology, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Thomas Bazié
- Department of Parasitology, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Cathérine Neya Ebou
- Department of Parasitology, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Estelle Lotio Dembélé
- Department of Parasitology, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Richard Balma
- Department of Medical Entomology, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Justin Goodwin
- Department of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, USA
| | - Martina Wade
- Department of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, USA
| | - Amy K Bei
- Department of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, USA
| | - Jean-Bosco Ouédraogo
- Department of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, USA; Department of Parasitology, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Brian D Foy
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Roch K Dabiré
- Department of Medical Entomology, Institut de Recherche en Sciences de la Santé, Bobo-Dioulasso, Burkina Faso
| | - Sunil Parikh
- Department of Epidemiology of Microbial Diseases, Yale University, New Haven, CT, USA
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Ozodiegwu ID, Ambrose M, Galatas B, Runge M, Nandi A, Okuneye K, Dhanoa NP, Maikore I, Uhomoibhi P, Bever C, Noor A, Gerardin J. Application of mathematical modelling to inform national malaria intervention planning in Nigeria. Malar J 2023; 22:137. [PMID: 37101146 PMCID: PMC10130303 DOI: 10.1186/s12936-023-04563-w] [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: 12/01/2022] [Accepted: 04/15/2023] [Indexed: 04/28/2023] Open
Abstract
BACKGROUND For their 2021-2025 National Malaria Strategic Plan (NMSP), Nigeria's National Malaria Elimination Programme (NMEP), in partnership with the World Health Organization (WHO), developed a targeted approach to intervention deployment at the local government area (LGA) level as part of the High Burden to High Impact response. Mathematical models of malaria transmission were used to predict the impact of proposed intervention strategies on malaria burden. METHODS An agent-based model of Plasmodium falciparum transmission was used to simulate malaria morbidity and mortality in Nigeria's 774 LGAs under four possible intervention strategies from 2020 to 2030. The scenarios represented the previously implemented plan (business-as-usual), the NMSP at an 80% or higher coverage level and two prioritized plans according to the resources available to Nigeria. LGAs were clustered into 22 epidemiological archetypes using monthly rainfall, temperature suitability index, vector abundance, pre-2010 parasite prevalence, and pre-2010 vector control coverage. Routine incidence data were used to parameterize seasonality in each archetype. Each LGA's baseline malaria transmission intensity was calibrated to parasite prevalence in children under the age of five years measured in the 2010 Malaria Indicator Survey (MIS). Intervention coverage in the 2010-2019 period was obtained from the Demographic and Health Survey, MIS, the NMEP, and post-campaign surveys. RESULTS Pursuing a business-as-usual strategy was projected to result in a 5% and 9% increase in malaria incidence in 2025 and 2030 compared with 2020, while deaths were projected to remain unchanged by 2030. The greatest intervention impact was associated with the NMSP scenario with 80% or greater coverage of standard interventions coupled with intermittent preventive treatment in infants and extension of seasonal malaria chemoprevention (SMC) to 404 LGAs, compared to 80 LGAs in 2019. The budget-prioritized scenario with SMC expansion to 310 LGAs, high bed net coverage with new formulations, and increase in effective case management rate at the same pace as historical levels was adopted as an adequate alternative for the resources available. CONCLUSIONS Dynamical models can be applied for relative assessment of the impact of intervention scenarios but improved subnational data collection systems are required to allow increased confidence in predictions at sub-national level.
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Affiliation(s)
- Ifeoma D Ozodiegwu
- Department of Preventive Medicine and Institute for Global Health, Northwestern University, Chicago, IL, USA.
| | | | - Beatriz Galatas
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Manuela Runge
- Department of Preventive Medicine and Institute for Global Health, Northwestern University, Chicago, IL, USA
| | - Aadrita Nandi
- Department of Preventive Medicine and Institute for Global Health, Northwestern University, Chicago, IL, USA
| | - Kamaldeen Okuneye
- Department of Preventive Medicine and Institute for Global Health, Northwestern University, Chicago, IL, USA
| | - Neena Parveen Dhanoa
- Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL, USA
| | - Ibrahim Maikore
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | | | | | - Abdisalan Noor
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Jaline Gerardin
- Department of Preventive Medicine and Institute for Global Health, Northwestern University, Chicago, IL, USA
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8
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Mbewe RB, Keven JB, Mangani C, Wilson ML, Mzilahowa T, Mathanga DP, Valim C, Laufer MK, Walker ED, Cohee LM. Genotyping of Anopheles mosquito blood meals reveals nonrandom human host selection: implications for human-to-mosquito Plasmodium falciparum transmission. Malar J 2023; 22:115. [PMID: 37029433 PMCID: PMC10080529 DOI: 10.1186/s12936-023-04541-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/22/2023] [Indexed: 04/09/2023] Open
Abstract
BACKGROUND Control of malaria parasite transmission can be enhanced by understanding which human demographic groups serve as the infectious reservoirs. Because vector biting can be heterogeneous, some infected individuals may contribute more to human-to-mosquito transmission than others. Infection prevalence peaks in school-age children, but it is not known how often they are fed upon. Genotypic profiling of human blood permits identification of individual humans who were bitten. The present investigation used this method to estimate which human demographic groups were most responsible for transmitting malaria parasites to Anopheles mosquitoes. It was hypothesized that school-age children contribute more than other demographic groups to human-to-mosquito malaria transmission. METHODS In a region of moderate-to-high malaria incidence in southeastern Malawi, randomly selected households were surveyed to collect human demographic information and blood samples. Blood-fed, female Anopheles mosquitoes were sampled indoors from the same houses. Genomic DNA from human blood samples and mosquito blood meals of human origin was genotyped using 24 microsatellite loci. The resultant genotypes were matched to identify which individual humans were sources of blood meals. In addition, Plasmodium falciparum DNA in mosquito abdomens was detected with polymerase chain reaction. The combined results were used to identify which humans were most frequently bitten, and the P. falciparum infection prevalence in mosquitoes that resulted from these blood meals. RESULTS Anopheles females selected human hosts non-randomly and fed on more than one human in 9% of the blood meals. Few humans contributed most of the blood meals to the Anopheles vector population. Children ≤ 5 years old were under-represented in mosquito blood meals while older males (31-75 years old) were over-represented. However, the largest number of malaria-infected blood meals was from school age children (6-15 years old). CONCLUSIONS The results support the hypothesis that humans aged 6-15 years are the most important demographic group contributing to the transmission of P. falciparum to the Anopheles mosquito vectors. This conclusion suggests that malaria control and prevention programmes should enhance efforts targeting school-age children and males.
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Affiliation(s)
- Rex B Mbewe
- Department of Entomology, Michigan State University, East Lansing, MI, USA.
- Department of Physics and Biochemical Sciences, Malawi University of Business and Applied Sciences, Blantyre, Malawi.
| | - John B Keven
- Department of Entomology, Michigan State University, East Lansing, MI, USA
- Department of Public Health, College of Health Sciences, University of California-Irvine, Irvine, CA, USA
| | - Charles Mangani
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Mark L Wilson
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Themba Mzilahowa
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Don P Mathanga
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Clarissa Valim
- Department of Global Health, Boston University School of Public Health, Boston, MA, USA
| | - Miriam K Laufer
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Edward D Walker
- Department of Entomology, Michigan State University, East Lansing, MI, USA
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Lauren M Cohee
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
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Corder RM, Arez AP, Ferreira MU. Individual variation in Plasmodium vivax malaria risk: Are repeatedly infected people just unlucky? PLoS Negl Trop Dis 2023; 17:e0011020. [PMID: 36634044 PMCID: PMC9836309 DOI: 10.1371/journal.pntd.0011020] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Extensive research has examined why some people have frequent Plasmodium falciparum malaria episodes in sub-Saharan Africa while others remain free of disease most of the time. In contrast, malaria risk heterogeneity remains little studied in regions where P. vivax is the dominant species. Are repeatedly infected people in vivax malaria settings such as the Amazon just unlucky? Here, we briefly review evidence that human genetic polymorphism and acquired immunity after repeated exposure to parasites can modulate the risk of P. vivax infection and disease in predictable ways. One-fifth of the hosts account for 80% or more of the community-wide vivax malaria burden and contribute disproportionally to onward transmission, representing a priority target of more intensive interventions to achieve malaria elimination. Importantly, high-risk individuals eventually develop clinical immunity, even in areas with very low or residual malaria transmission, and may constitute a large but silent parasite reservoir.
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Affiliation(s)
- Rodrigo M. Corder
- Department of Epidemiology and Biostatistics, University of California, Berkeley School of Public Health, Berkeley, California, United States of America
| | - Ana Paula Arez
- Global Health and Tropical Medicine (GHTM), institute of Hygiene and Tropical Medicine, NOVA University of Lisbon, Lisbon, Portugal
| | - Marcelo U. Ferreira
- Global Health and Tropical Medicine (GHTM), institute of Hygiene and Tropical Medicine, NOVA University of Lisbon, Lisbon, Portugal
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- * E-mail: ,
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10
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Gonçalves BP, Pérez-Caballero R, Barry A, Gaoussou S, Lewin A, Issiaka D, Keita S, Diarra BS, Mahamar A, Attaher O, Narum DL, Kurtis JD, Dicko A, Duffy PE, Fried M. Natural History of Malaria Infections During Early Childhood in Twins. J Infect Dis 2023; 227:171-178. [PMID: 35849702 DOI: 10.1093/infdis/jiac294] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 06/06/2022] [Accepted: 07/15/2022] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The frequency and clinical presentation of malaria infections show marked heterogeneity in epidemiological studies. However, deeper understanding of this variability is hampered by the difficulty in quantifying all relevant factors. Here, we report the history of malaria infections in twins, who are exposed to the same in utero milieu, share genetic factors, and are similarly exposed to vectors. METHODS Data were obtained from a Malian longitudinal birth cohort. Samples from 25 twin pairs were examined for malaria infection and antibody responses. Bayesian models were developed for the number of infections during follow-up. RESULTS In 16 of 25 pairs, both children were infected and often developed symptoms. In 8 of 25 pairs, only 1 twin was infected, but usually only once or twice. Statistical models suggest that this pattern is not inconsistent with twin siblings having the same underlying infection rate. In a pair with discordant hemoglobin genotype, parasite densities were consistently lower in the child with hemoglobin AS, but antibody levels were similar. CONCLUSIONS By using a novel design, we describe residual variation in malaria phenotypes in naturally matched children and confirm the important role of environmental factors, as suggested by the between-twin pair heterogeneity in malaria history.
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Affiliation(s)
- Bronner P Gonçalves
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Raúl Pérez-Caballero
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Amadou Barry
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Santara Gaoussou
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Alexandra Lewin
- Department of Medical Statistics, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Djibrilla Issiaka
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekouba Keita
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Bacary S Diarra
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Almahamoudou Mahamar
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Oumar Attaher
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - David L Narum
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jonathan D Kurtis
- Center for International Health Research, Rhode Island Hospital, and Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence, Rhode Island, USA
| | - Alassane Dicko
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies of Bamako, Bamako, Mali
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Pinda PG, Msaky DS, Muyaga LL, Mshani IH, Njalambaha RM, Kihonda J, Bwanaly H, Ngowo HS, Kaindoa EW, Koekemoer LL, Okumu FO. Relationships between biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes in south-eastern Tanzania. Malar J 2022; 21:365. [PMID: 36461058 PMCID: PMC9719249 DOI: 10.1186/s12936-022-04389-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/16/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Malaria transmission can be highly heterogeneous between and within localities, and is influenced by factors such as survival and biting frequencies of Anopheles mosquitoes. This study investigated the relationships between the biological age, distance from aquatic habitats and pyrethroid resistance status of Anopheles funestus mosquitoes, which currently dominate malaria transmission in south-east Tanzania. The study also examined how such relationships may influence malaria transmission and control. METHODS Female An. funestus were collected in houses located 50-100 m, 150-200 m or over 200 m from the nearest known aquatic habitats. The mosquitoes were exposed to 1×, 5× and 10× the diagnostic doses of deltamethrin or permethrin, or to the synergist, piperonyl butoxide (PBO) followed by the pyrethroids, then monitored for 24 h-mortality. Ovaries of exposed and non-exposed mosquitoes were dissected to assess parity as a proxy for biological age. Adults emerging from larval collections in the same villages were tested against the same insecticides at 3-5, 8-11 or 17-20 days old. FINDINGS Mosquitoes collected nearest to the aquatic habitats (50-100 m) had the lowest mortalities compared to other distances, with a maximum of 51% mortality at 10× permethrin. For the age-synchronized mosquitoes collected as larvae, the insecticide-induced mortality assessed at both the diagnostic and multiplicative doses (1×, 5× and 10×) increased with mosquito age. The highest mortalities at 1× doses were observed among the oldest mosquitoes (17-20 days). At 10× doses, mortalities were 99% (permethrin) and 76% (deltamethrin) among 8-11 day-olds compared to 80% (permethrin) and 58% (deltamethrin) among 3-5 day-olds. Pre-exposure to PBO increased the potency of both pyrethroids. The proportion of parous females was highest among mosquitoes collected farthest from the habitats. CONCLUSION In this specific setting, older An. funestus and those collected farthest from the aquatic habitats (near the centre of the village) were more susceptible to pyrethroids than the younger ones and those caught nearest to the habitats. These findings suggest that pyrethroid-based interventions may remain at least moderately effective despite widespread pyrethroid-resistance, by killing the older, less-resistant and potentially-infective mosquitoes. Further studies should investigate how and whether these observations could be exploited to optimize malaria control in different settings.
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Affiliation(s)
- Polius G Pinda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
| | - Dickson S Msaky
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Issa H Mshani
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Rukiyah M Njalambaha
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Japhet Kihonda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Hamis Bwanaly
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania
- School of Life Sciences and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, Faculty of Health Sciences, Centre for Emerging Zoonotic and Parasitic Diseases, University of the Witwatersrand, National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, United Republic of Tanzania.
- School of Life Sciences and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, United Republic of Tanzania.
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.
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12
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Lubinda J, Bi Y, Haque U, Lubinda M, Hamainza B, Moore AJ. Spatio-temporal monitoring of health facility-level malaria trends in Zambia and adaptive scaling for operational intervention. COMMUNICATIONS MEDICINE 2022; 2:79. [PMID: 35789566 PMCID: PMC9249860 DOI: 10.1038/s43856-022-00144-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 06/15/2022] [Indexed: 12/02/2022] Open
Abstract
Background The spatial and temporal variability inherent in malaria transmission within countries implies that targeted interventions for malaria control in high-burden settings and subnational elimination are a practical necessity. Identifying the spatio-temporal incidence, risk, and trends at different administrative geographies within malaria-endemic countries and monitoring them in near real-time as change occurs is crucial for developing and introducing cost-effective, subnational control and elimination intervention strategies. Methods This study developed intelligent data analytics incorporating Bayesian trend and spatio-temporal Integrated Laplace Approximation models to analyse high-burden over 32 million reported malaria cases from 1743 health facilities in Zambia between 2009 and 2015. Results The results show that at least 5.4 million people live in catchment areas with increasing trends of malaria, covering over 47% of all health facilities, while 5.7 million people live in areas with a declining trend (95% CI), covering 27% of health facilities. A two-scale spatio-temporal trend comparison identified significant differences between health facilities and higher-level districts, and the pattern observed in the southeastern region of Zambia provides the first evidence of the impact of recently implemented localised interventions. Conclusions The results support our recommendation for an adaptive scaling approach when implementing national malaria monitoring, control and elimination strategies and a particular need for stratified subnational approaches targeting high-burden regions with increasing disease trends. Strong clusters along borders with highly endemic countries in the north and south of Zambia underscore the need for coordinated cross-border malaria initiatives and strategies. Malaria is an infectious disease that is widespread in many African countries. Malaria transmission within a country can vary between regions, so tailored interventions for malaria control and elimination targeted to different regions are necessary. To achieve this, it is important to measure and monitor the frequency of malaria infections, its risk, and trends at different geographic administrative scales. This study analysed over 32 million reported malaria cases from 1743 health facilities in Zambia between 2009 and 2015. The results showed an increasing national trend in malaria risk and malaria infection frequency and identified differences between health facility and district trends. These findings support a flexible approach when implementing and expanding national malaria monitoring, control and elimination strategies, especially in areas bordering countries where malaria is widespread, cross-border movement is common, and cross-border initiatives could be beneficial. Lubinda et al. analyse over 32 million health-facility reported malaria cases in Zambia (2009–15) to examine spatially-structured temporal trends. They observe overall increasing trends in risk and rates and highlight the potential benefits of using an adaptive scaling approach in national malaria strategies, and a need for cross-border initiatives.
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13
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Mirzohreh ST, Safarpour H, Pagheh AS, Bangoura B, Barac A, Ahmadpour E. Malaria prevalence in HIV-positive children, pregnant women, and adults: a systematic review and meta-analysis. PARASITES & VECTORS 2022; 15:324. [PMID: 36104731 PMCID: PMC9472338 DOI: 10.1186/s13071-022-05432-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/15/2022] [Indexed: 11/10/2022]
Abstract
Abstract
Background
Malaria in human immunodeficiency virus (HIV)-positive patients is an ever-increasing global burden for human health. The present meta-analysis summarizes published literature on the prevalence of malaria infection in HIV-positive children, pregnant women and adults.
Methods
This study followed the PRISMA guideline. The PubMed, Science Direct, Google Scholar, Scopus and Cochrane databases were searched for relevant entries published between 1 January 1983 and 1 March 2020. All peer-reviewed original papers evaluating the prevalence of malaria among HIV-positive patients were included. Incoherence and heterogeneity between studies were quantified by the I2 index and Cochran’s Q test. Publication and population biases were assessed with funnel plots, and Egger’s regression asymmetry test.
Results
A total of 106 studies were included in this systematic review. The average prevalence of malaria among HIV-positive children, HIV-positive pregnant women and HIV-positive adults was 39.4% (95% confidence interval [CI]: 26.6–52.9), 32.3% (95% CI = 26.3–38.6) and 27.3% (95% CI = 20.1–35.1), respectively. In adult patients with HIV, CD4+ (cluster of differentiation 4) < 200 cells/µl and age < 40 years were associated with a significant increase in the odds of malaria infection (odds ratio [OR] = 1.5, 95% CI = 1.2–1.7 and OR = 1.1, 95% CI = 1–1.3, respectively). Antiretroviral therapy (ART) and being male were associated with a significant decrease in the chance of malaria infection in HIV-positive adults (OR = 0.8, 95% CI = 0.7–0.9 and OR = 0.2, 95% CI = 0.2–0.3, respectively). In pregnant women with HIV, CD4+ count < 200 cells/µl was related to a higher risk for malaria infection (OR = 1.5, 95% CI = 1.1–1.9).
Conclusions
This systematic review demonstrates that malaria infection is concerningly common among HIV-positive children, pregnant women and adults. Among HIV-positive adults, ART medication and being male were associated with a substantial decrease in infection with malaria. For pregnant women, CD4+ count of < 200 cells/µl was a considerable risk factor for malaria infection.
Graphical Abstract
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14
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Oke CE, Ingham VA, Walling CA, Reece SE. Vector control: agents of selection on malaria parasites? Trends Parasitol 2022; 38:890-903. [PMID: 35981937 DOI: 10.1016/j.pt.2022.07.006] [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: 03/14/2022] [Revised: 06/30/2022] [Accepted: 07/21/2022] [Indexed: 10/15/2022]
Abstract
Insect vectors are responsible for spreading many infectious diseases, yet interactions between pathogens/parasites and insect vectors remain poorly understood. Filling this knowledge gap matters because vectors are evolving in response to the deployment of vector control tools (VCTs). Yet, whilst the evolutionary responses of vectors to VCTs are being carefully monitored, the knock-on consequences for parasite evolution have been overlooked. By examining how mosquito responses to VCTs impact upon malaria parasite ecology, we derive a framework for predicting parasite responses. Understanding how VCTs affect the selection pressures imposed on parasites could help to mitigate against parasite evolution that leads to unfavourable epidemiological outcomes. Furthermore, anticipating parasite evolution will inform monitoring strategies for VCT programmes as well as uncovering novel VCT strategies.
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Affiliation(s)
- Catherine E Oke
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK.
| | - Victoria A Ingham
- Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Im Neuenheimer Feld 324, 69210 Heidelberg, Germany
| | - Craig A Walling
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
| | - Sarah E Reece
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK; Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3FL, UK
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15
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Stanley CC, Mukaka M, Kazembe LN, Buchwald AG, Mathanga DP, Laufer MK, Chirwa TF. Analysis of Recurrent Times-to-Clinical Malaria Episodes and Plasmodium falciparum Parasitemia: A Joint Modeling Approach Applied to a Cohort Data. FRONTIERS IN EPIDEMIOLOGY 2022; 2:924783. [PMID: 38455327 PMCID: PMC10911024 DOI: 10.3389/fepid.2022.924783] [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: 04/20/2022] [Accepted: 06/08/2022] [Indexed: 03/09/2024]
Abstract
Background Recurrent clinical malaria episodes due to Plasmodium falciparum parasite infection are common in endemic regions. With each infection, acquired immunity develops, making subsequent disease episodes less likely. To capture the effect of acquired immunity to malaria, it may be necessary to model recurrent clinical disease episodes jointly with P. falciparum parasitemia data. A joint model of longitudinal parasitemia and time-to-first clinical malaria episode (single-event joint model) may be inaccurate because acquired immunity is lost when subsequent episodes are excluded. This study's informativeness assessed whether joint modeling of recurrent clinical malaria episodes and parasitemia is more accurate than a single-event joint model where the subsequent episodes are ignored. Methods The single event joint model comprised Cox Proportional Hazards (PH) sub-model for time-to-first clinical malaria episode and Negative Binomial (NB) mixed-effects sub-model for the longitudinal parasitemia. The recurrent events joint model extends the survival sub-model to a Gamma shared frailty model to include all recurrent clinical episodes. The models were applied to cohort data from Malawi. Simulations were also conducted to assess the performance of the model under different conditions. Results The recurrent events joint model, which yielded higher hazard ratios of clinical malaria, was more precise and in most cases produced smaller standard errors than the single-event joint model; hazard ratio (HR) = 1.42, [95% confidence interval [CI]: 1.22, 2.03] vs. HR = 1.29, [95% CI:1.60, 2.45] among participants who reported not to use LLINs every night compared to those who used the nets every night; HR = 0.96, [ 95% CI: 0.94, 0.98] vs. HR = 0.81, [95% CI: 0.75, 0.88] for each 1-year increase in participants' age; and HR = 1.36, [95% CI: 1.05, 1.75] vs. HR = 1.10, [95% CI: 0.83, 4.11] for observations during the rainy season compared to the dry season. Conclusion The recurrent events joint model in this study provides a way of estimating the risk of recurrent clinical malaria in a cohort where the effect of immunity on malaria disease acquired due to P. falciparum parasitemia with aging is captured. The simulation study has shown that if correctly specified, the recurrent events joint model can give risk estimates with low bias.
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Affiliation(s)
- Christopher C. Stanley
- Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Mavuto Mukaka
- Oxford Centre for Tropical Medicine and Global Health, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, Thailand
| | | | - Andrea G. Buchwald
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Don P. Mathanga
- Malaria Alert Center, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Miriam K. Laufer
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Tobias F. Chirwa
- Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
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Sedda L, McCann RS, Kabaghe AN, Gowelo S, Mburu MM, Tizifa TA, Chipeta MG, van den Berg H, Takken W, van Vugt M, Phiri KS, Cain R, Tangena JAA, Jones CM. Hotspots and super-spreaders: Modelling fine-scale malaria parasite transmission using mosquito flight behaviour. PLoS Pathog 2022; 18:e1010622. [PMID: 35793345 PMCID: PMC9292116 DOI: 10.1371/journal.ppat.1010622] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 07/18/2022] [Accepted: 05/27/2022] [Indexed: 11/19/2022] Open
Abstract
Malaria hotspots have been the focus of public health managers for several years due to the potential elimination gains that can be obtained from targeting them. The identification of hotspots must be accompanied by the description of the overall network of stable and unstable hotspots of malaria, especially in medium and low transmission settings where malaria elimination is targeted. Targeting hotspots with malaria control interventions has, so far, not produced expected benefits. In this work we have employed a mechanistic-stochastic algorithm to identify clusters of super-spreader houses and their related stable hotspots by accounting for mosquito flight capabilities and the spatial configuration of malaria infections at the house level. Our results show that the number of super-spreading houses and hotspots is dependent on the spatial configuration of the villages. In addition, super-spreaders are also associated to house characteristics such as livestock and family composition. We found that most of the transmission is associated with winds between 6pm and 10pm although later hours are also important. Mixed mosquito flight (downwind and upwind both with random components) were the most likely movements causing the spread of malaria in two out of the three study areas. Finally, our algorithm (named MALSWOTS) provided an estimate of the speed of malaria infection progression from house to house which was around 200-400 meters per day, a figure coherent with mark-release-recapture studies of Anopheles dispersion. Cross validation using an out-of-sample procedure showed accurate identification of hotspots. Our findings provide a significant contribution towards the identification and development of optimal tools for efficient and effective spatio-temporal targeted malaria interventions over potential hotspot areas.
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Affiliation(s)
- Luigi Sedda
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, United Kingdom
| | - Robert S. McCann
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alinune N. Kabaghe
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Steven Gowelo
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- MAC Communicable Diseases Action Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Monicah M. Mburu
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Tinashe A. Tizifa
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Center for Tropical Medicine and Travel Medicine, University of Amsterdam, The Netherlands
| | - Michael G. Chipeta
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Michèle van Vugt
- Center for Tropical Medicine and Travel Medicine, University of Amsterdam, The Netherlands
| | - Kamija S. Phiri
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Russell Cain
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, United Kingdom
| | - Julie-Anne A. Tangena
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Christopher M. Jones
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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17
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Ajayi OM, Marlman JM, Gleitz LA, Smith ES, Piller BD, Krupa JA, Vinauger C, Benoit JB. Behavioral and postural analyses establish sleep-like states for mosquitoes that can impact host landing and blood feeding. J Exp Biol 2022; 225:275280. [PMID: 35502753 PMCID: PMC9234499 DOI: 10.1242/jeb.244032] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 04/21/2022] [Indexed: 10/18/2022]
Abstract
Sleep is an evolutionarily conserved process that has been described in different animal systems. For insects, sleep characterization has been primarily achieved using behavioral and electrophysiological correlates in a few systems. Sleep in mosquitoes, which are important vectors of disease-causing pathogens, has not been directly examined. This is surprising as circadian rhythms, which have been well studied in mosquitoes, influence sleep in other systems. In this study, we characterized sleep in mosquitoes using body posture analysis and behavioral correlates and quantified the effect of sleep deprivation on sleep rebound, host landing and blood-feeding propensity. Body and appendage position metrics revealed a clear distinction between the posture of mosquitoes in their putative sleep and awake states for multiple species, which correlate with a reduction in responsiveness to host cues. Sleep assessment informed by these posture analyses indicated significantly more sleep during periods of low activity. Nighttime and daytime sleep deprivation resulting from the delivery of vibration stimuli induced sleep rebound in the subsequent phase in day and night active mosquitoes, respectively. Lastly, sleep deprivation suppressed host landing in both laboratory and field settings, and impaired blood feeding of a human host when mosquitoes would normally be active. These results suggest that quantifiable sleep states occur in mosquitoes and highlight the potential epidemiological importance of mosquito sleep.
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Affiliation(s)
- Oluwaseun M Ajayi
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Justin M Marlman
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Lucas A Gleitz
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Evan S Smith
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Benjamin D Piller
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Justyna A Krupa
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Clément Vinauger
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Joshua B Benoit
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
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18
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Altahir O, AbdElbagi H, Abubakr M, Siddig EE, Ahmed A, Mohamed NS. Blood meal profile and positivity rate with malaria parasites among different malaria vectors in Sudan. Malar J 2022; 21:124. [PMID: 35428264 PMCID: PMC9013081 DOI: 10.1186/s12936-022-04157-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 04/07/2022] [Indexed: 12/03/2022] Open
Abstract
Background Malaria is a life-threatening public health problem globally with particularly heavy burden in the sub-Saharan Africa including Sudan. The understanding of feeding preference of malaria vectors on different hosts is a major challenge for hindering the transmission cycle of malaria. In this study, blood meals taken by blood-fed Anopheles mosquitoes collected from the field in malaria endemic areas of Sudan were analysed for source of blood meal and malaria parasite presence. Methods Anopheles mosquitoes were collected from different regions in Sudan: Khartoum state, Sennar state, Northern state, and El Gedarif state between September 2020 and February 2021. Anopheles mosquitoes were collected using the standard pyrethrum spray catch and back-pack aspirator. Mosquito samples were sorted and morphologically identified to species level using international identification keys. Morphologically identified mosquito species were also confirmed using PCR. Genomic DNA was extracted from mosquitoes for molecular identification of blood meal source and parasite detection. The presence of Plasmodium species DNA in each mosquito sample was investigated using semi-nested PCR. Frequency of each blood meal source, Anopheles mosquito vector, and malaria parasite detected was calculated. Positivity rate of each fed female Anopheles mosquito was calculated for each species. Results A total of 2132 Anopheles mosquitoes were collected. 571 (26.8%) were males and 1561 (73.2%) were females classified based on their abdominal status into 1048 (67.1%) gravid, 274 (17.6%) fed, and 239 (15.3%) unfed females. Among the blood fed Anopheles mosquitoes, 263 (96.0%) were morphologically identified and confirmed using PCR to Anopheles arabiensis, 9 (3.3%) to Anopheles stephensi, and 2 (0.7%) to Anopheles rufipes. Of 274 blood-fed An. arabiensis, 68 (25.9%) fed on mixed blood meals from human and cattle, 8 (3.0%) fed on cattle and goat, and 13 (4.8%) fed on human, cattle and goat. For single blood meal sources, 70 (26.6%) fed on human, 95 (36.1%) fed on cattle, 8 (3.0%) fed on goat, and 1 (0.4%) fed on dog. While An. rufipes and An. stephensi fed on dog (2; 0.75%) and cattle (9; 3.3%), respectively. Plasmodium parasite detection in the blood meals showed that 25/274 (9.1%) An. arabiensis meals were positive for Plasmodium vivax and 19/274 (6.9%) An. arabiensis meals were positive for Plasmodium falciparum. The rate of positivity of An. arabiensis with any Plasmodium species was 16.7%. However, the positivity rate with P. falciparum only was 7.2%, while P. vivax was 9.5%. Both An. rufipes and An. stephensi were having positivity rates of 0.0% each. Conclusions This study which was mainly on blood-fed Anopheles mosquitoes showed a diversity in the type of diet from human, cattle, and goat. Anopheles mosquitoes especially An. arabiensis in Sudan, are opportunistic blood feeders and can feed broadly on both human and cattle. The application of blood meal identification is not only important in malaria vector epidemiological surveillance but also is very useful in areas where arthropods exhibit zoophilic feeding behaviour for mammals.
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19
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Showering A, Martinez J, Benavente ED, Gezan SA, Jones RT, Oke C, Tytheridge S, Pretorius E, Scott D, Allen RL, D'Alessandro U, Lindsay SW, Armour JAL, Pickett J, Logan JG. Skin microbiome alters attractiveness to Anopheles mosquitoes. BMC Microbiol 2022; 22:98. [PMID: 35410125 PMCID: PMC9004177 DOI: 10.1186/s12866-022-02502-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 03/21/2022] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Some people produce specific body odours that make them more attractive than others to mosquitoes, and consequently are at higher risk of contracting vector-borne diseases. The skin microbiome can break down carbohydrates, fatty acids and peptides on the skin into volatiles that mosquitoes can differentiate. RESULTS Here, we examined how skin microbiome composition of women differs in relation to level of attractiveness to Anopheles coluzzii mosquitoes, to identify volatiles in body odour and metabolic pathways associated with individuals that tend to be poorly-attractive to mosquitoes. We used behavioural assays to measure attractiveness of participants to An. coluzzii mosquitoes, 16S rRNA amplicon sequencing of the bacteria sampled from the skin and gas chromatography of volatiles in body odour. We found differences in skin microbiome composition between the poorly- and highly-attractive groups, particularly eight Amplicon Sequence Variants (ASVs) belonging to the Proteobacteria, Actinobacteria and Firmicutes phyla. Staphylococcus 2 ASVs are four times as abundant in the highly-attractive compared to poorly-attractive group. Associations were found between these ASVs and volatiles known to be attractive to Anopheles mosquitoes. Propanoic pathways are enriched in the poorly-attractive participants compared to those found to be highly-attractive. CONCLUSIONS Our findings suggest that variation in attractiveness of people to mosquitoes is related to the composition of the skin microbiota, knowledge that could improve odour-baited traps or other next generation vector control tools.
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Affiliation(s)
- Alicia Showering
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
| | - Julien Martinez
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, 464 Bearsden Road, Glasgow, G61 1QH, UK
| | - Ernest Diez Benavente
- Department of Experimental Cardiology, University Medical Center Utrecht, Utrecht, the Netherlands
| | | | - Robert T Jones
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Catherine Oke
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Scott Tytheridge
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Elizabeth Pretorius
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Darren Scott
- Department of Medical Statistics, London School of Hygiene & Tropical Medicine, London, UK
| | - Rachel L Allen
- Institute for Infection and Immunity, St George's, University of London, London, UK
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, Gambia
| | | | - John A L Armour
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, UK
| | - John Pickett
- School of Chemistry, Cardiff University, Cardiff, Wales, UK
| | - James G Logan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
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20
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Evans MV, Bhatnagar S, Drake JM, Murdock CC, Mukherjee S. Socio‐ecological dynamics in urban systems: An integrative approach to mosquito‐borne disease in Bengaluru, India. PEOPLE AND NATURE 2022. [DOI: 10.1002/pan3.10311] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Michelle V. Evans
- MIVEGEC, Univ. Montpellier, CNRS, IRD Montpellier France
- Odum School of Ecology University of Georgia Athens GA USA
- Center for Ecology of Infectious Diseases University of Georgia Athens GA USA
| | - Siddharth Bhatnagar
- Observatoire de Genève Université de Genève Sauverny Switzerland
- School of Arts and Sciences Azim Premji University Bengaluru India
| | - John M. Drake
- Odum School of Ecology University of Georgia Athens GA USA
- Center for Ecology of Infectious Diseases University of Georgia Athens GA USA
| | - Courtney C. Murdock
- Odum School of Ecology University of Georgia Athens GA USA
- Center for Ecology of Infectious Diseases University of Georgia Athens GA USA
- Department of Entomology, College of Agriculture and Life Sciences Cornell University Ithaca NY USA
- Cornell Institute of Host‐Microbe Interactions and Disease Cornell University Ithaca NY USA
- Northeast Regional Center of Excellence in Vector‐borne Diseases Cornell University Ithaca NY USA
| | - Shomen Mukherjee
- School of Arts and Sciences Azim Premji University Bengaluru India
- Biology and Life Sciences Division, School of Arts and Sciences Ahmedabad University Ahmedabad Gujarat India
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21
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Huber JH, Koepfli C, España G, Nekkab N, White MT, Alex Perkins T. How radical is radical cure? Site-specific biases in clinical trials underestimate the effect of radical cure on Plasmodium vivax hypnozoites. Malar J 2021; 20:479. [PMID: 34930278 PMCID: PMC8686294 DOI: 10.1186/s12936-021-04017-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 12/08/2021] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Plasmodium vivax blood-stage relapses originating from re-activating hypnozoites are a major barrier for control and elimination of this disease. Radical cure is a form of therapy capable of addressing this problem. Recent clinical trials of radical cure have yielded efficacy estimates ranging from 65 to 94%, with substantial variation across trial sites. METHODS An analysis of simulated trial data using a transmission model was performed to demonstrate that variation in efficacy estimates across trial sites can arise from differences in the conditions under which trials are conducted. RESULTS The analysis revealed that differences in transmission intensity, heterogeneous exposure and relapse rate can yield efficacy estimates ranging as widely as 12-78%, despite simulating trial data under the uniform assumption that treatment had a 75% chance of clearing hypnozoites. A longer duration of prophylaxis leads to a greater measured efficacy, particularly at higher transmission intensities, making the comparison between the protection of different radical cure treatment regimens against relapse more challenging. Simulations show that vector control and parasite genotyping offer two potential means to yield more standardized efficacy estimates that better reflect prevention of relapse. CONCLUSIONS Site-specific biases are likely to contribute to variation in efficacy estimates both within and across clinical trials. Future clinical trials can reduce site-specific biases by conducting trials in low-transmission settings where re-infections from mosquito bite are less common, by preventing re-infections using vector control measures, or by identifying and excluding likely re-infections that occur during follow-up, by using parasite genotyping methods.
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Affiliation(s)
- John H Huber
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.
| | - Cristian Koepfli
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Guido España
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Narimane Nekkab
- Unité Malaria: Parasites et Hôtes, Département Parasites et Insectes Vecteur, Institut Pasteur, Paris, France
| | - Michael T White
- Unité Malaria: Parasites et Hôtes, Département Parasites et Insectes Vecteur, Institut Pasteur, Paris, France
| | - T Alex Perkins
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
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22
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Amoah B, McCann RS, Kabaghe AN, Mburu M, Chipeta MG, Moraga P, Gowelo S, Tizifa T, van den Berg H, Mzilahowa T, Takken W, van Vugt M, Phiri KS, Diggle PJ, Terlouw DJ, Giorgi E. Identifying Plasmodium falciparum transmission patterns through parasite prevalence and entomological inoculation rate. eLife 2021; 10:65682. [PMID: 34672946 PMCID: PMC8530514 DOI: 10.7554/elife.65682] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 09/30/2021] [Indexed: 11/13/2022] Open
Abstract
Background Monitoring malaria transmission is a critical component of efforts to achieve targets for elimination and eradication. Two commonly monitored metrics of transmission intensity are parasite prevalence (PR) and the entomological inoculation rate (EIR). Comparing the spatial and temporal variations in the PR and EIR of a given geographical region and modelling the relationship between the two metrics may provide a fuller picture of the malaria epidemiology of the region to inform control activities. Methods Using geostatistical methods, we compare the spatial and temporal patterns of Plasmodium falciparum EIR and PR using data collected over 38 months in a rural area of Malawi. We then quantify the relationship between EIR and PR by using empirical and mechanistic statistical models. Results Hotspots identified through the EIR and PR partly overlapped during high transmission seasons but not during low transmission seasons. The estimated relationship showed a 1-month delayed effect of EIR on PR such that at lower levels of EIR, increases in EIR are associated with rapid rise in PR, whereas at higher levels of EIR, changes in EIR do not translate into notable changes in PR. Conclusions Our study emphasises the need for integrated malaria control strategies that combine vector and human host managements monitored by both entomological and parasitaemia indices. Funding This work was supported by Stichting Dioraphte grant number 13050800.
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Affiliation(s)
- Benjamin Amoah
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Robert S McCann
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands.,Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, United States
| | - Alinune N Kabaghe
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, Netherlands
| | - Monicah Mburu
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands.,Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Michael G Chipeta
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi.,Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Paula Moraga
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, United Kingdom.,Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Steven Gowelo
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands.,Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Tinashe Tizifa
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Academic Medical Centre, University of Amsterdam, Amsterdam, Netherlands
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands
| | - Themba Mzilahowa
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Willem Takken
- Laboratory of Entomology, Wageningen University and Research, Wageningen, Netherlands
| | - Michele van Vugt
- Academic Medical Centre, University of Amsterdam, Amsterdam, Netherlands
| | - Kamija S Phiri
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Peter J Diggle
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
| | - Dianne J Terlouw
- Department of Public Health, College of Medicine, University of Malawi, Blantyre, Malawi.,Malawi-Liverpool Wellcome Trust Research Programme, Blantyre, Malawi.,Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Emanuele Giorgi
- Centre for Health Informatics, Computing, and Statistics (CHICAS), Lancaster Medical School, Lancaster University, Lancaster, United Kingdom
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23
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Keven JB, Katusele M, Vinit R, Rodríguez-Rodríguez D, Hetzel MW, Robinson LJ, Laman M, Karl S, Foran DR, Walker ED. Nonrandom Selection and Multiple Blood Feeding of Human Hosts by Anopheles Vectors: Implications for Malaria Transmission in Papua New Guinea. Am J Trop Med Hyg 2021; 105:1747-1758. [PMID: 34583342 PMCID: PMC8641310 DOI: 10.4269/ajtmh.21-0210] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 07/21/2021] [Indexed: 11/07/2022] Open
Abstract
Nonrandom selection and multiple blood feeding of human hosts by Anopheles mosquitoes may exacerbate malaria transmission. Both patterns of blood feeding and their relationship to malaria epidemiology were investigated in Anopheles vectors in Papua New Guinea (PNG). Blood samples from humans and mosquito blood meals were collected in villages and human genetic profiles ("fingerprints") were analyzed by genotyping 23 microsatellites and a sex-specific marker. Frequency of blood meals acquired from different humans, identified by unique genetic profiles, was fitted to Poisson and negative binomial distributions to test for nonrandom patterns of host selection. Blood meals with more than one genetic profiles were classified as mosquitoes that fed on multiple humans. The age of a person bitten by a mosquito was determined by matching the blood-meal genetic profile to the villagers' genetic profiles. Malaria infection in humans was determined by PCR test of blood samples. The results show nonrandom distribution of blood feeding among humans, with biased selection toward males and individuals aged 15-30 years. Prevalence of Plasmodium falciparum infection was higher in this age group, suggesting males in this age range could be super-spreaders of malaria parasites. The proportion of mosquitoes that fed on multiple humans ranged from 6% to 13% among villages. The patterns of host utilization observed here can amplify transmission and contribute to the persistence of malaria in PNG despite efforts to suppress it with insecticidal bed nets. Excessive feeding on males aged 15-30 years underscores the importance of targeted interventions focusing on this demographic group.
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Affiliation(s)
- John B. Keven
- Department of Microbiology and Molecular Genetics, and Department of Entomology, Michigan State University, East Lansing, Michigan
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Michelle Katusele
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Rebecca Vinit
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Daniela Rodríguez-Rodríguez
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Department of Epidemiology and Public Health, University of Basel, Basel, Switzerland
| | - Manuel W. Hetzel
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Department of Epidemiology and Public Health, University of Basel, Basel, Switzerland
| | - Leanne J. Robinson
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
- Vector-Borne Diseases and Tropical Public Health Group, Burnet Institute, Melbourne, Victoria, Australia
- Division of Population Health and Immunity, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, Victoria, Australia
| | - Moses Laman
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Stephan Karl
- Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Queensland, Australia
| | - David R. Foran
- School of Criminal Justice and Department of Integrative Biology, Michigan State University, Michigan
| | - Edward D. Walker
- Department of Microbiology and Molecular Genetics, and Department of Entomology, Michigan State University, East Lansing, Michigan
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24
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Thongsripong P, Hyman JM, Kapan DD, Bennett SN. Human-Mosquito Contact: A Missing Link in Our Understanding of Mosquito-Borne Disease Transmission Dynamics. ANNALS OF THE ENTOMOLOGICAL SOCIETY OF AMERICA 2021; 114:397-414. [PMID: 34249219 PMCID: PMC8266639 DOI: 10.1093/aesa/saab011] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Indexed: 05/26/2023]
Abstract
Despite the critical role that contact between hosts and vectors, through vector bites, plays in driving vector-borne disease (VBD) transmission, transmission risk is primarily studied through the lens of vector density and overlooks host-vector contact dynamics. This review article synthesizes current knowledge of host-vector contact with an emphasis on mosquito bites. It provides a framework including biological and mathematical definitions of host-mosquito contact rate, blood-feeding rate, and per capita biting rates. We describe how contact rates vary and how this variation is influenced by mosquito and vertebrate factors. Our framework challenges a classic assumption that mosquitoes bite at a fixed rate determined by the duration of their gonotrophic cycle. We explore alternative ecological assumptions based on the functional response, blood index, forage ratio, and ideal free distribution within a mechanistic host-vector contact model. We highlight that host-vector contact is a critical parameter that integrates many factors driving disease transmission. A renewed focus on contact dynamics between hosts and vectors will contribute new insights into the mechanisms behind VBD spread and emergence that are sorely lacking. Given the framework for including contact rates as an explicit component of mathematical models of VBD, as well as different methods to study contact rates empirically to move the field forward, researchers should explicitly test contact rate models with empirical studies. Such integrative studies promise to enhance understanding of extrinsic and intrinsic factors affecting host-vector contact rates and thus are critical to understand both the mechanisms driving VBD emergence and guiding their prevention and control.
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Affiliation(s)
- Panpim Thongsripong
- Department of Microbiology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA 94118, USA
| | - James M Hyman
- Department of Mathematics, Tulane University, 6823 St. Charles Avenue, New Orleans, LA 70118, USA
| | - Durrell D Kapan
- Department of Entomology and Center for Comparative Genomics, Institute of Biodiversity Sciences and Sustainability, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA 94118, USA
- Center for Conservation and Research Training, Pacific Biosciences Research Center, University of Hawai’i at Manoa, 3050 Maile Way, Honolulu, HI 96822
| | - Shannon N Bennett
- Department of Microbiology, California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA 94118, USA
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25
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Guglielmo F, Sanou A, Churcher T, Ferguson HM, Ranson H, Sherrard-Smith E. Quantifying individual variability in exposure risk to mosquito bites in the Cascades region, Burkina Faso. Malar J 2021; 20:44. [PMID: 33461560 PMCID: PMC7814650 DOI: 10.1186/s12936-020-03538-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 12/07/2020] [Indexed: 12/21/2022] Open
Abstract
Background The Cascades region, Burkina Faso, has a high malaria burden despite reported high insecticide-treated mosquito net (ITN) use. Human and vector activities outside the hours when indoor interventions offer direct protection from infectious bites potentially increase exposure risk to bites from malaria-transmitting Anopheles mosquitoes. This work investigated the degree of variation in human behaviour both between individuals and through time (season) to quantify how it impacts exposure to malaria vectors. Methods Patterns in human overnight activity (18:00–06:00) to quantify time spent using an ITN across 7 successive nights in two rural communities, Niakore (N = 24 participants) and Toma (71 participants), were observed in the dry and rainy seasons, between 2017 and 2018. Hourly human landing Anopheles mosquito catches were conducted in Niakore specifically, and Cascades region generally, between 2016 and 2017. Data were statistically combined to estimate seasonal variation in time spent outdoors and Anopheles bites received per person per night (bpppn). Results Substantial variability in exposure to outdoor Anopheles bites was detected within and between communities across seasons. In October, when Anopheles densities are highest, an individual’s risk of Anopheles bites ranged from 2.2 to 52.2 bites per person per night (bpppn) within the same week with variable risk dependent on hours spent indoors. Comparably higher outdoor human activity was observed in April and July but, due to lower Anopheles densities estimated, bpppn were 0.2–4.7 and 0.5–32.0, respectively. Males and people aged over 21 years were predicted to receive more bites in both sentinel villages. Conclusion This work presents one of the first clear descriptions of the degree of heterogeneity in time spent outdoors between people and across the year. Appreciation of sociodemographic, cultural and entomological activities will help refine approaches to vector control.
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Affiliation(s)
- Federica Guglielmo
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | - Antoine Sanou
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK. .,Centre National de Recherche et de Formation sur le Paludisme, BP 2208, Ouagadougou 01, Burkina Faso.
| | - Thomas Churcher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, St Mary's Campus, London, W2 1PG, UK
| | - Heather M Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | - Hilary Ranson
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, St Mary's Campus, London, W2 1PG, UK.
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26
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O'Meara WP, Simmons R, Bullins P, Freedman B, Abel L, Mangeni J, Taylor SM, Obala AA. Mosquito Exposure and Malaria Morbidity: A Microlevel Analysis of Household Mosquito Populations and Malaria in a Population-Based Longitudinal Cohort in Western Kenya. J Infect Dis 2021; 221:1176-1184. [PMID: 31665350 DOI: 10.1093/infdis/jiz561] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 10/23/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Malaria morbidity is highly overdispersed in the population. Fine-scale differences in mosquito exposure may partially explain this heterogeneity in individual malaria outcomes. METHODS In 38 households we explored the effect of household-level mosquito exposure and individual insecticide-treated net (ITN) use on relative risk (RR) of confirmed malaria. We conducted monthly active surveillance (n = 254; 2624 person-months) and weekly mosquito collection (2092 household-days of collection), and used molecular techniques to confirm human blood feeding and exposure to infectious mosquitoes. RESULTS Of 1494 female Anopheles (89.8% Anopheles gambiae sensu lato), 88.3% were fed, 51.9% had a human blood meal, and 9.2% were sporozoite infected. In total, 168 laboratory-confirmed malaria episodes were reported (incidence rate 0.064 episodes per person-month at risk; 95% confidence interval [CI], .055-.074). Malaria risk was directly associated with exposure to sporozoite-infected mosquitoes (RR, 1.24; 95% CI, 1.11-1.38). No direct effect was measured between ITN use and malaria morbidity; however, ITN use did moderate the effect of mosquito exposure on morbidity. CONCLUSIONS Malaria risk increases linearly with vector density and feeding success for persons with low ITN use. In contrast, malaria risk among high ITN users is consistently low and insensitive to variation in mosquito exposure.
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Affiliation(s)
- Wendy Prudhomme O'Meara
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA.,Department of Medicine, Duke University, Durham, North Carolina, USA.,School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Ryan Simmons
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA.,Department of Biostatistics and Bioinformatics, Duke University, Durham, North Carolina, USA
| | - Paige Bullins
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA
| | - Betsy Freedman
- Department of Medicine, Duke University, Durham, North Carolina, USA
| | - Lucy Abel
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret, Kenya
| | - Judith Mangeni
- School of Nursing, College of Health Sciences, Moi University, Eldoret, Kenya
| | - Steve M Taylor
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA.,Department of Medicine, Duke University, Durham, North Carolina, USA
| | - Andrew A Obala
- School of Medicine, College of Health Sciences, Moi University, Eldoret, Kenya
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27
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Martinez J, Showering A, Oke C, Jones RT, Logan JG. Differential attraction in mosquito-human interactions and implications for disease control. Philos Trans R Soc Lond B Biol Sci 2020; 376:20190811. [PMID: 33357061 PMCID: PMC7776937 DOI: 10.1098/rstb.2019.0811] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Mosquito-borne diseases are a major burden on human health worldwide and their eradication through vector control methods remains challenging. In particular, the success of vector control interventions for targeting diseases such as malaria is under threat, in part due to the evolution of insecticide resistance, while for other diseases effective control solutions are still lacking. The rate at which mosquitoes encounter and bite humans is a key determinant of their capacity for disease transmission. Future progress is strongly reliant on improving our understanding of the mechanisms leading to a mosquito bite. Here, we review the biological factors known to influence the attractiveness of mosquitoes to humans, such as body odour, the skin microbiome, genetics and infection by parasites. We identify the knowledge gaps around the relative contribution of each factor, and the potential links between them, as well as the role of natural selection in shaping vector–host–parasite interactions. Finally, we argue that addressing these questions will contribute to improving current tools and the development of novel interventions for the future. This article is part of the theme issue ‘Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Julien Martinez
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Alicia Showering
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Catherine Oke
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Robert T Jones
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - James G Logan
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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28
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Hastings IM, Hardy D, Kay K, Sharma R. Incorporating genetic selection into individual-based models of malaria and other infectious diseases. Evol Appl 2020; 13:2723-2739. [PMID: 33294019 PMCID: PMC7691459 DOI: 10.1111/eva.13077] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 06/16/2020] [Accepted: 07/11/2020] [Indexed: 01/04/2023] Open
Abstract
INTRODUCTION Control strategies for human infections are often investigated using individual-based models (IBMs) to quantify their impact in terms of mortality, morbidity and impact on transmission. Genetic selection can be incorporated into the IBMs to track the spread of mutations whose origin and spread are driven by the intervention and which subsequently undermine the control strategy; typical examples are mutations which encode drug resistance or diagnosis- or vaccine-escape phenotypes. METHODS AND RESULTS We simulated the spread of malaria drug resistance using the IBM OpenMalaria to investigate how the finite sizes of IBMs require strategies to optimally incorporate genetic selection. We make four recommendations. Firstly, calculate and report the selection coefficients, s, of the advantageous allele as the key genetic parameter. Secondly, use these values of "s" to calculate the wait time until a mutation successfully establishes itself in the pathogen population. Thirdly, identify the inherent limits of the IBM to robustly estimate small selection coefficients. Fourthly, optimize computational efficacy: when "s" is small, fewer replicates of larger IBMs may be more efficient than a larger number of replicates of smaller size. DISCUSSION The OpenMalaria IBM of malaria was an exemplar and the same principles apply to IBMs of other diseases.
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Affiliation(s)
| | - Diggory Hardy
- Swiss Tropical and Public Health InstituteBaselSwitzerland
- University of BaselBaselSwitzerland
| | | | - Raman Sharma
- Liverpool School of Tropical MedicineLiverpoolUK
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29
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Ajayi OM, Eilerts DF, Bailey ST, Vinauger C, Benoit JB. Do Mosquitoes Sleep? Trends Parasitol 2020; 36:888-897. [PMID: 32952061 PMCID: PMC8094063 DOI: 10.1016/j.pt.2020.08.004] [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: 06/05/2020] [Revised: 08/17/2020] [Accepted: 08/20/2020] [Indexed: 10/23/2022]
Abstract
Sleep is a phenomenon conserved across the animal kingdom, where studies on Drosophila melanogaster have revealed that sleep phenotypes and molecular underpinnings are similar to those in mammals. However, little is known about sleep in blood-feeding arthropods, which have a critical role in public health as disease vectors. Specifically, sleep studies in mosquitoes are lacking despite considerable focus on how circadian processes, which have a central role in regulating sleep/wake cycles, impact activity, feeding, and immunity. Here, we review observations which suggest that sleep-like states likely occur in mosquitoes and discuss the potential role of sleep in relation to mosquito biology and their ability to function as disease vectors.
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Affiliation(s)
- Oluwaseun M Ajayi
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA. @mail.uc.edu
| | - Diane F Eilerts
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Samuel T Bailey
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Clément Vinauger
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
| | - Joshua B Benoit
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA. @uc.edu
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30
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Graumans W, Jacobs E, Bousema T, Sinnis P. When Is a Plasmodium-Infected Mosquito an Infectious Mosquito? Trends Parasitol 2020; 36:705-716. [PMID: 32620501 DOI: 10.1016/j.pt.2020.05.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 12/19/2022]
Abstract
Plasmodium parasites experience significant bottlenecks as they transit through the mosquito and are transmitted to their mammalian host. Oocyst prevalence on mosquito midguts and sporozoite prevalence in salivary glands are nevertheless commonly used to confirm successful malaria transmission, assuming that these are reliable indicators of the mosquito's capacity to give rise to secondary infections. Here we discuss recent insights in sporogonic development and transmission bottlenecks for Plasmodium. We highlight critical gaps in our knowledge and frame their importance in understanding the human and mosquito reservoirs of infection. A better understanding of the events that lead to successful inoculation of infectious sporozoites by mosquitoes is critical to designing effective interventions to shrink the malaria map.
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Affiliation(s)
- Wouter Graumans
- Radboud University Medical Center, Radboud Institute for Health Sciences, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Ella Jacobs
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Teun Bousema
- Radboud University Medical Center, Radboud Institute for Health Sciences, Department of Medical Microbiology, Nijmegen, The Netherlands; Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.
| | - Photini Sinnis
- Department of Molecular Microbiology and Immunology, and Johns Hopkins Malaria Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
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31
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Hamley JID, Milton P, Walker M, Basáñez MG. Modelling exposure heterogeneity and density dependence in onchocerciasis using a novel individual-based transmission model, EPIONCHO-IBM: Implications for elimination and data needs. PLoS Negl Trop Dis 2019; 13:e0007557. [PMID: 31805049 PMCID: PMC7006940 DOI: 10.1371/journal.pntd.0007557] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/07/2020] [Accepted: 06/18/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Density dependence in helminth establishment and heterogeneity in exposure to infection are known to drive resilience to interventions based on mass drug administration (MDA). However, the interaction between these processes is poorly understood. We developed a novel individual-based model for onchocerciasis transmission, EPIONCHO-IBM, which accounts for both processes. We fit the model to pre-intervention epidemiological data and explore parasite dynamics during MDA with ivermectin. METHODOLOGY/PRINCIPAL FINDINGS Density dependence and heterogeneity in exposure to blackfly (vector) bites were estimated by fitting the model to matched pre-intervention microfilarial prevalence, microfilarial intensity and vector biting rate data from savannah areas of Cameroon and Côte d'Ivoire/Burkina Faso using Latin hypercube sampling. Transmission dynamics during 25 years of annual and biannual ivermectin MDA were investigated. Density dependence in parasite establishment within humans was estimated for different levels of (fixed) exposure heterogeneity to understand how parametric uncertainty may influence treatment dynamics. Stronger overdispersion in exposure to blackfly bites results in the estimation of stronger density-dependent parasite establishment within humans, consequently increasing resilience to MDA. For all levels of exposure heterogeneity tested, the model predicts a departure from the functional forms for density dependence assumed in the deterministic version of the model. CONCLUSIONS/SIGNIFICANCE This is the first, stochastic model of onchocerciasis, that accounts for and estimates density-dependent parasite establishment in humans alongside exposure heterogeneity. Capturing the interaction between these processes is fundamental to our understanding of resilience to MDA interventions. Given that uncertainty in these processes results in very different treatment dynamics, collecting data on exposure heterogeneity would be essential for improving model predictions during MDA. We discuss possible ways in which such data may be collected as well as the importance of better understanding the effects of immunological responses on establishing parasites prior to and during ivermectin treatment.
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Affiliation(s)
- Jonathan I. D. Hamley
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- * E-mail:
| | - Philip Milton
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hatfield, Untied Kingdom
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
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32
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Urbaniak J, Janowski D, Jacewski B. Isolation of nucleic acids using silicon dioxide powder as a tool for environmental monitoring. ENVIRONMENTAL MONITORING AND ASSESSMENT 2019; 191:732. [PMID: 31705223 PMCID: PMC6841745 DOI: 10.1007/s10661-019-7840-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 09/24/2019] [Indexed: 06/10/2023]
Abstract
Isolation and purification of nucleic acids are basic laboratory procedures used in molecular analysis supporting determination of organisms in environmental monitoring. However, many different methods of isolation are commonly used, often being designed for a particular type of DNA extraction. While researchers commonly decide on commercial isolation kits for their ease of use and efficiency, they require large amounts of studied tissue, and the cost of purchasing such kits over a long run can be high. To provide an alternative to using commercial kits, we have developed a simple, rapid, cost-effective, and reliable protocol for DNA isolation from cultured fungi on slants and from dried fungal samples using silica particles (silicon dioxide powder) in chaotropic conditions. With the presented method, it is possible to isolate good-quality DNA from fungi in less than 1.5 h, using easily accessible chemicals. Compared with other methods employing CTAB or commercial kits, it allows fast, easy, and cheap DNA purification from two main sources of fungi routinely used for research. In addition to the method protocol, we also provide advice for further optimization of the isolation process to account for specific conditions, making the procedure more useful.
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Affiliation(s)
- Jacek Urbaniak
- Department of Botany and Plant Ecology, Wrocław University of Plant Sciences, pl. Grunwaldzki 24a, 50-363, Wrocław, Poland.
| | - Daniel Janowski
- Institute of Dendrobiology PAS, ul. Parkowa 5, 62-035, Kórnik, Poland
| | - Brayan Jacewski
- Department of Botany and Plant Ecology, Wrocław University of Plant Sciences, pl. Grunwaldzki 24a, 50-363, Wrocław, Poland
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33
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Cooper L, Kang SY, Bisanzio D, Maxwell K, Rodriguez-Barraquer I, Greenhouse B, Drakeley C, Arinaitwe E, G Staedke S, Gething PW, Eckhoff P, Reiner RC, Hay SI, Dorsey G, Kamya MR, Lindsay SW, Grenfell BT, Smith DL. Pareto rules for malaria super-spreaders and super-spreading. Nat Commun 2019; 10:3939. [PMID: 31477710 PMCID: PMC6718398 DOI: 10.1038/s41467-019-11861-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 08/05/2019] [Indexed: 11/09/2022] Open
Abstract
Heterogeneity in transmission is a challenge for infectious disease dynamics and control. An 80-20 "Pareto" rule has been proposed to describe this heterogeneity whereby 80% of transmission is accounted for by 20% of individuals, herein called super-spreaders. It is unclear, however, whether super-spreading can be attributed to certain individuals or whether it is an unpredictable and unavoidable feature of epidemics. Here, we investigate heterogeneous malaria transmission at three sites in Uganda and find that super-spreading is negatively correlated with overall malaria transmission intensity. Mosquito biting among humans is 90-10 at the lowest transmission intensities declining to less than 70-30 at the highest intensities. For super-spreaders, biting ranges from 70-30 down to 60-40. The difference, approximately half the total variance, is due to environmental stochasticity. Super-spreading is thus partly due to super-spreaders, but modest gains are expected from targeting super-spreaders.
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Affiliation(s)
- Laura Cooper
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.,Department of Veterinary Medicine, Cambridge University, Cambridge, UK
| | - Su Yun Kang
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Donal Bisanzio
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK.,RTI International, Washington, DC, USA.,Epidemiology and Public Health Division, School of Medicine, University of Nottingham, Nottingham, UK
| | - Kilama Maxwell
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Isabel Rodriguez-Barraquer
- Department of Epidemiology, Johns Hopkins University, Baltimore, MD, USA.,Department of Medicine, University of California, San Francisco, CA, USA
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Chris Drakeley
- London School of Hygiene & Tropical Medicine, London, UK
| | - Emmanuel Arinaitwe
- Infectious Diseases Research Collaboration, Kampala, Uganda.,London School of Hygiene & Tropical Medicine, London, UK
| | | | - Peter W Gething
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | | | - Robert C Reiner
- Department of Health Metrics Sciences, School of Medicine, University of Washington, Seattle, WA, USA.,Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USA
| | - Simon I Hay
- Department of Health Metrics Sciences, School of Medicine, University of Washington, Seattle, WA, USA.,Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USA
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Moses R Kamya
- School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Steven W Lindsay
- School of Biological and Biomedical Sciences, Durham University, Durham, UK
| | - Bryan T Grenfell
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.,Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ, USA.,Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
| | - David L Smith
- Department of Health Metrics Sciences, School of Medicine, University of Washington, Seattle, WA, USA. .,Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USA.
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34
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Stresman G, Bousema T, Cook J. Malaria Hotspots: Is There Epidemiological Evidence for Fine-Scale Spatial Targeting of Interventions? Trends Parasitol 2019; 35:822-834. [PMID: 31474558 DOI: 10.1016/j.pt.2019.07.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/29/2019] [Accepted: 07/29/2019] [Indexed: 12/20/2022]
Abstract
As data at progressively granular spatial scales become available, the temptation is to target interventions to areas with higher malaria transmission - so-called hotspots - with the aim of reducing transmission in the wider community. This paper reviews literature to determine if hotspots are an intrinsic feature of malaria epidemiology and whether current evidence supports hotspot-targeted interventions. Hotspots are a consistent feature of malaria transmission at all endemicities. The smallest spatial unit capable of supporting transmission is the household, where peri-domestic transmission occurs. Whilst the value of focusing interventions to high-burden areas is evident, there is currently limited evidence that local-scale hotspots fuel transmission. As boundaries are often uncertain, there is no conclusive evidence that hotspot-targeted interventions accelerate malaria elimination.
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Affiliation(s)
- Gillian Stresman
- Infection Biology Department, London School of Hygiene and Tropical Medicine, London, UK.
| | - Teun Bousema
- Radboud University Medical Centre, Department of Microbiology, HB Nijmegen, The Netherlands.
| | - Jackie Cook
- Medical Research Council (MRC) Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
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35
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Chakim I, Pumpaibool T. The diversity of Anopheles blood feeding patterns suggests different malaria protection strategies in different localities. F1000Res 2019; 8:1217. [PMID: 33110498 PMCID: PMC7578570 DOI: 10.12688/f1000research.19341.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/24/2019] [Indexed: 03/31/2024] Open
Abstract
Background: Malaria is a significant health burden for many countries worldwide. Insecticide-treated bed nets and mosquito repellent are considered effective methods for preventing Anopheles bites. However, changes in the biological properties of the vector have led to a reduction in their effectiveness. Most published studies have only investigated the human population factor, not the dynamics of vector behavior. Therefore, this study aims to investigate the importance of primary vector activity for selecting an appropriate malaria protection strategy. Methods: Initially, active case detection (ACD) was carried out in western and eastern parts of Indonesia, Jambi and Sumba, to confirm their endemicity level. According to the 2016 national health report of Indonesia, Jambi has an annual parasite index (API) of 0.14 and Sumba has an API of 5.41. A series of entomological observations were carried out to compare the biting activity of Anopheles vector in two localities, with a total of 216 houses and catchers (108 in each study site). Results: The results indicated that endemicity at the sub-district level is higher than that at the provincial level. Only Anopheles balabacensi was found to be exophagic. Multiple comparisons found different biting times between the sites, suggesting that early evening (18.00-20.00) is most likely to be the time when mosquitos transmit the Plasmodium parasite in Jambi, while during sleeping hours (21.00-01.00) is the peak biting time of Anopheles mosquitos in Sumba. Conclusions: The study demonstrates the importance of Anopheles species blood feeding patterns in selecting an appropriate malaria protection strategy.
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Affiliation(s)
- Irfanul Chakim
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
- Faculty of Public Health, Universitas Muhammadiyah Semarang, Kota Semarang, Jawa Tengah, 50273, Indonesia
| | - Tepanata Pumpaibool
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
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36
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Chakim I, Pumpaibool T. The diversity of Anopheles blood feeding patterns suggests different malaria protection strategies in different localities. F1000Res 2019; 8:1217. [PMID: 33110498 PMCID: PMC7578570 DOI: 10.12688/f1000research.19341.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/12/2020] [Indexed: 03/31/2024] Open
Abstract
Background: Malaria is a significant health burden for many countries worldwide. Insecticide-treated bed nets and mosquito repellent are considered effective methods for preventing Anopheles bites. However, changes in the biological properties of the vector have led to a reduction in their effectiveness. Most published studies have only investigated the human population factor, not the dynamics of vector behavior. Therefore, this study aims to investigate the importance of primary vector activity for selecting an appropriate malaria protection strategy. Methods: Initially, active case detection (ACD) was carried out in western and eastern parts of Indonesia, Jambi and Sumba, to confirm their endemicity level. According to the 2016 national health report of Indonesia, Jambi has an annual parasite index (API) of 0.14 and Sumba has an API of 5.41. A series of entomological observations were carried out to compare the biting activity of Anopheles vectors in two localities, with a total of 216 houses and 216 catchers (108 at each study site). Results: The results indicated that endemicity at the sub-district level is higher than that at the provincial level. Only Anopheles balabacensi was found to be exophagic. Multiple comparisons found different biting times between the sites, suggesting that early evening (18.00-20.00) is most likely to be the time when mosquitoes transmit the Plasmodium parasite in Jambi, while during sleeping hours (21.00-01.00) is the peak biting time of Anopheles mosquitoes in Sumba. Conclusions: The study demonstrates the importance of Anopheles species blood feeding patterns in selecting an appropriate malaria protection strategy.
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Affiliation(s)
- Irfanul Chakim
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
- Faculty of Public Health, Universitas Muhammadiyah Semarang, Kota Semarang, Jawa Tengah, 50273, Indonesia
| | - Tepanata Pumpaibool
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
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37
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Chakim I, Pumpaibool T. The diversity of Anopheles blood feeding patterns suggests different malaria protection strategies in different localities. F1000Res 2019; 8:1217. [PMID: 33110498 PMCID: PMC7578570 DOI: 10.12688/f1000research.19341.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/29/2019] [Indexed: 03/31/2024] Open
Abstract
Background: Malaria is a significant health burden for many countries worldwide. Insecticide-treated bed nets and mosquito repellent are considered effective methods for preventing Anopheles bites. However, changes in the biological properties of the vector have led to a reduction in their effectiveness. Most published studies have only investigated the human population factor, not the dynamics of vector behavior. Therefore, this study aims to investigate the importance of primary vector activity for selecting an appropriate malaria protection strategy. Methods: Initially, active case detection (ACD) was carried out in western and eastern parts of Indonesia, Jambi and Sumba, to confirm their endemicity level. According to the 2016 national health report of Indonesia, Jambi has an annual parasite index (API) of 0.14 and Sumba has an API of 5.41. A series of entomological observations were carried out to compare the biting activity of Anopheles vector in two localities, with a total of 216 houses and 216 catchers (108 in each study site). Results: The results indicated that endemicity at the sub-district level is higher than that at the provincial level. Only Anopheles balabacensi was found to be exophagic. Multiple comparisons found different biting times between the sites, suggesting that early evening (18.00-20.00) is most likely to be the time when mosquitoes transmit the Plasmodium parasite in Jambi, while during sleeping hours (21.00-01.00) is the peak biting time of Anopheles mosquitoes in Sumba. Conclusions: The study demonstrates the importance of Anopheles species blood feeding patterns in selecting an appropriate malaria protection strategy.
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Affiliation(s)
- Irfanul Chakim
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
- Faculty of Public Health, Universitas Muhammadiyah Semarang, Kota Semarang, Jawa Tengah, 50273, Indonesia
| | - Tepanata Pumpaibool
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
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38
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Chakim I, Pumpaibool T. The diversity of Anopheles blood feeding patterns suggests different malaria protection strategies in different localities. F1000Res 2019; 8:1217. [PMID: 33110498 PMCID: PMC7578570 DOI: 10.12688/f1000research.19341.4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/15/2020] [Indexed: 11/20/2022] Open
Abstract
Background: Malaria is a significant health burden for many countries worldwide. Insecticide-treated bed nets and mosquito repellent are considered effective methods for preventing Anopheles bites. However, changes in the biological properties of the vector have led to a reduction in their effectiveness. The vector has been studied, but the behaviour has been poorly examined. Therefore, this study aims to investigate the importance of primary vector activity for selecting an appropriate malaria protection strategy. Methods: Initially, active case detection (ACD) was carried out in western and eastern parts of Indonesia, Jambi and Sumba, to confirm their endemicity level. According to the 2016 national health report of Indonesia, Jambi has an annual parasite index (API) of 0.14 and Sumba has an API of 5.41. A series of entomological observations were carried out to compare the biting activity of Anopheles vectors in two localities, with a total of 216 houses and 216 catchers (108 at each study site). Results: The results indicated that endemicity at the sub-district level is higher than that at the provincial level. Only Anopheles balabacensi was found to be exophagic. Multiple comparisons found different biting times between the sites, suggesting that early evening (18.00-20.00) is most likely to be the time when mosquitoes transmit the Plasmodium parasite in Jambi, while during sleeping hours (21.00-01.00) is the peak biting time of Anopheles mosquitoes in Sumba. Conclusions: The study demonstrates the importance of Anopheles species blood feeding patterns in selecting an appropriate malaria protection strategy.
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Affiliation(s)
- Irfanul Chakim
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
- Faculty of Public Health, Universitas Muhammadiyah Semarang, Kota Semarang, Jawa Tengah, 50273, Indonesia
| | - Tepanata Pumpaibool
- College of Public Health Sciences, Chulalongkorn University, Bangkok, 10330, Thailand
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39
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Barry A, Behet MC, Nébié I, Lanke K, Grignard L, Ouedraogo A, Soulama I, Drakeley C, Sauerwein R, Bolscher JM, Dechering KJ, Bousema T, Tiono AB, Gonçalves BP. Functional antibodies against Plasmodium falciparum sporozoites are associated with a longer time to qPCR-detected infection among schoolchildren in Burkina Faso. Wellcome Open Res 2019; 3:159. [PMID: 30828645 PMCID: PMC6381444 DOI: 10.12688/wellcomeopenres.14932.2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/23/2019] [Indexed: 11/23/2022] Open
Abstract
Background: Individuals living in malaria-endemic regions develop immunity against severe malaria, but it is unclear whether immunity against pre-erythrocytic stages that blocks initiation of blood-stage infection after parasite inoculation develops following continuous natural exposure. Methods: We cleared schoolchildren living in an area (health district of Saponé, Burkina Faso) with highly endemic seasonal malaria of possible sub-patent infections and examined them weekly for incident infections by nested PCR. Plasma samples collected at enrolment were used to quantify antibodies to the pre-eryhrocytic-stage antigens circumsporozoite protein (CSP) and Liver stage antigen 1 (LSA-1).
In vitro sporozoite gliding inhibition and hepatocyte invasion inhibition by naturally acquired antibodies were assessed using
Plasmodium falciparum NF54 sporozoites. Associations between antibody responses, functional pre-erythrocytic immunity phenotypes and time to infection detected by
18S quantitative PCR were studied. Results: A total of 51 children were monitored. Anti-CSP antibody titres showed a positive association with sporozoite gliding motility inhibition (P<0.0001, Spearman’s ρ=0.76).
In vitro hepatocyte invasion was inhibited by naturally acquired antibodies (median inhibition, 19.4% [IQR 15.2-40.9%]), and there were positive correlations between invasion inhibition and gliding inhibition (P=0.005, Spearman’s ρ=0.67) and between invasion inhibition and CSP-specific antibodies (P=0.002, Spearman’s ρ=0.76). Survival analysis indicated longer time to infection in individuals displaying higher-than-median sporozoite gliding inhibition activity (P=0.01), although this association became non-significant after adjustment for blood-stage immunity (P = 0.06). Conclusions: In summary, functional antibodies against the pre-erythrocytic stages of malaria infection are acquired in children who are repeatedly exposed to
Plasmodium parasites. This immune response does not prevent them from becoming infected during a malaria transmission season, but might delay the appearance of blood stage parasitaemia. Our approach could not fully separate the effects of pre-erythrocytic-specific and blood-stage-specific antibody-mediated immune responses
in vivo; epidemiological studies powered and designed to address this important question should become a research priority.
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Affiliation(s)
- Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.,Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marije C Behet
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Issa Nébié
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Robert Sauerwein
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
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40
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Barry A, Behet MC, Nébié I, Lanke K, Grignard L, Ouedraogo A, Soulama I, Drakeley C, Sauerwein R, Bolscher JM, Dechering KJ, Bousema T, Tiono AB, Gonçalves BP. Functional antibodies against Plasmodium falciparum sporozoites are associated with a longer time to qPCR-detected infection among schoolchildren in Burkina Faso. Wellcome Open Res 2019; 3:159. [PMID: 30828645 DOI: 10.12688/wellcomeopenres.14932.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/03/2018] [Indexed: 01/29/2023] Open
Abstract
Background: Individuals living in malaria-endemic regions develop immunity against severe malaria, but it is unclear whether immunity against pre-erythrocytic stages that blocks initiation of blood-stage infection after parasite inoculation develops following continuous natural exposure. Methods: We cleared schoolchildren living in an area (health district of Saponé, Burkina Faso) with highly endemic seasonal malaria of possible sub-patent infections and examined them weekly for incident infections by nested PCR. Plasma samples collected at enrolment were used to quantify antibodies to the pre-eryhrocytic-stage antigens circumsporozoite protein (CSP) and Liver stage antigen 1 (LSA-1). In vitro sporozoite gliding inhibition and hepatocyte invasion inhibition by naturally acquired antibodies were assessed using Plasmodium falciparum NF54 sporozoites. Associations between antibody responses, functional pre-erythrocytic immunity phenotypes and time to infection detected by 18S quantitative PCR were studied. Results: A total of 51 children were monitored. Anti-CSP antibody titres showed a positive association with sporozoite gliding motility inhibition (P<0.0001, Spearman's ρ=0.76). In vitro hepatocyte invasion was inhibited by naturally acquired antibodies (median inhibition, 19.4% [IQR 15.2-40.9%]), and there were positive correlations between invasion inhibition and gliding inhibition (P=0.005, Spearman's ρ=0.67) and between invasion inhibition and CSP-specific antibodies (P=0.002, Spearman's ρ=0.76). Survival analysis indicated longer time to infection in individuals displaying higher-than-median sporozoite gliding inhibition activity (P=0.01), although this association became non-significant after adjustment for blood-stage immunity (P = 0.06). Conclusions: In summary, functional antibodies against the pre-erythrocytic stages of malaria infection are acquired in children who are repeatedly exposed to Plasmodium parasites. This immune response does not prevent them from becoming infected during a malaria transmission season, but might delay the appearance of blood stage parasitaemia. Our approach could not fully separate the effects of pre-erythrocytic-specific and blood-stage-specific antibody-mediated immune responses in vivo; epidemiological studies powered and designed to address this important question should become a research priority.
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Affiliation(s)
- Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.,Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Marije C Behet
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Issa Nébié
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alphonse Ouedraogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Robert Sauerwein
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
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41
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Giraud E, Martin O, Yakob L, Rogers M. Quantifying Leishmania Metacyclic Promastigotes from Individual Sandfly Bites Reveals the Efficiency of Vector Transmission. Commun Biol 2019; 2:84. [PMID: 30854476 PMCID: PMC6395631 DOI: 10.1038/s42003-019-0323-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 01/22/2019] [Indexed: 01/12/2023] Open
Abstract
Predicting how Leishmania will respond to control efforts requires an understanding of their transmission strategy. Using real-time quantitative PCR to quantify infectious metacyclic and non-metacyclic forms in mouse skin from single sandfly bites we show that most transmissions were highly enriched for infectious parasites. However, a quarter of sandflies were capable of transmitting high doses containing more non-infectious promastigotes from the vector's midgut. Mouse infections replicating "high" to "low" quality, low-dose transmissions confirmed clear differences in the pathology of the infection and their onward transmissibility back to sandflies. Borrowing methods originally developed to account for exposure heterogeneity among hosts, we show how these high-dose, low-quality transmitters act as super-spreading vectors, capable of inflating Leishmania transmission potential by as much as six-fold. These results highlight the hidden potential of transmission of mixed Leishmania promastigote stages on disease prevalence and the role of dose heterogeneity as an underlying strategy for efficient transmission.
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Affiliation(s)
- Emilie Giraud
- Department of Immunology and Infection, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.,Institut Pasteur, 25-28 rue du Dr Roux 75015, Paris, France
| | - Oihane Martin
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Laith Yakob
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Matthew Rogers
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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42
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Martin LB, Addison B, Bean AGD, Buchanan KL, Crino OL, Eastwood JR, Flies AS, Hamede R, Hill GE, Klaassen M, Koch RE, Martens JM, Napolitano C, Narayan EJ, Peacock L, Peel AJ, Peters A, Raven N, Risely A, Roast MJ, Rollins LA, Ruiz-Aravena M, Selechnik D, Stokes HS, Ujvari B, Grogan LF. Extreme Competence: Keystone Hosts of Infections. Trends Ecol Evol 2019; 34:303-314. [PMID: 30704782 PMCID: PMC7114649 DOI: 10.1016/j.tree.2018.12.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/10/2018] [Accepted: 12/13/2018] [Indexed: 12/20/2022]
Abstract
Individual hosts differ extensively in their competence for parasites, but traditional research has discounted this variation, partly because modeling such heterogeneity is difficult. This discounting has diminished as tools have improved and recognition has grown that some hosts, the extremely competent, can have exceptional impacts on disease dynamics. Most prominent among these hosts are the superspreaders, but other forms of extreme competence (EC) exist and others await discovery; each with potentially strong but distinct implications for disease emergence and spread. Here, we propose a framework for the study and discovery of EC, suitable for different host-parasite systems, which we hope enhances our understanding of how parasites circulate and evolve in host communities.
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Affiliation(s)
- Lynn B Martin
- Global and Planetary Health, University of South Florida, Tampa, Florida 33620, USA.
| | - BriAnne Addison
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | - Andrew G D Bean
- CSIRO Health & Biosecurity at the Australian Animal Health Laboratory, Geelong, VIC 3220, Australia
| | - Katherine L Buchanan
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | - Ondi L Crino
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | - Justin R Eastwood
- School of Biological Sciences, Monash University, VIC 3800, Australia
| | - Andrew S Flies
- Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7008, Australia
| | - Rodrigo Hamede
- School of Natural Sciences, University of Tasmania, Hobart, TAS 7001, Australia
| | - Geoffrey E Hill
- Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
| | - Marcel Klaassen
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | - Rebecca E Koch
- School of Biological Sciences, Monash University, VIC 3800, Australia
| | - Johanne M Martens
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | | | - Edward J Narayan
- School of Science and Health, Western Sydney University, Penrith, NSW 2751, Australia
| | - Lee Peacock
- School of Biological Sciences, Monash University, VIC 3800, Australia
| | - Alison J Peel
- Environmental Futures Research Institute, Griffith University, Nathan, QLD 4111, Australia
| | - Anne Peters
- School of Biological Sciences, Monash University, VIC 3800, Australia
| | - Nynke Raven
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | - Alice Risely
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | - Michael J Roast
- School of Biological Sciences, Monash University, VIC 3800, Australia
| | - Lee A Rollins
- School of Biological, Earth and Environmental Sciences, Evolution & Ecology Research Centre, University of New South Wales, Sydney, NSW 2052, Australia
| | - Manuel Ruiz-Aravena
- School of Natural Sciences, University of Tasmania, Hobart, TAS 7001, Australia
| | - Dan Selechnik
- School of Life and Environmental Sciences (SOLES), University of Sydney, Sydney, NSW 2006, Australia
| | - Helena S Stokes
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | - Beata Ujvari
- School of Life and Environmental Sciences, Deakin University, Geelong Waurn Ponds, VIC 3216, Australia
| | - Laura F Grogan
- Environmental Futures Research Institute, Griffith University, Nathan, QLD 4111, Australia
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43
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Orsborne J, Furuya-Kanamori L, Jeffries CL, Kristan M, Mohammed AR, Afrane YA, O'Reilly K, Massad E, Drakeley C, Walker T, Yakob L. Using the human blood index to investigate host biting plasticity: a systematic review and meta-regression of the three major African malaria vectors. Malar J 2018; 17:479. [PMID: 30563533 PMCID: PMC6299493 DOI: 10.1186/s12936-018-2632-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 12/14/2018] [Indexed: 12/17/2022] Open
Abstract
Background The proportion of mosquito blood-meals that are of human origin, referred to as the ‘human blood index’ or HBI, is a key determinant of malaria transmission. Methods A systematic review was conducted followed by meta-regression of the HBI for the major African malaria vectors. Results Evidence is presented for higher HBI among Anopheles gambiae (M/S forms and Anopheles coluzzii/An. gambiae sensu stricto are not distinguished for most studies and, therefore, combined) as well as Anopheles funestus when compared with Anopheles arabiensis (prevalence odds ratio adjusted for collection location [i.e. indoor or outdoor]: 1.62; 95% CI 1.09–2.42; 1.84; 95% CI 1.35–2.52, respectively). This finding is in keeping with the entomological literature which describes An. arabiensis to be more zoophagic than the other major African vectors. However, analysis also revealed that HBI was more associated with location of mosquito captures (R2 = 0.29) than with mosquito (sibling) species (R2 = 0.11). Conclusions These findings call into question the appropriateness of current methods of assessing host preferences among disease vectors and have important implications for strategizing vector control. Electronic supplementary material The online version of this article (10.1186/s12936-018-2632-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- James Orsborne
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Luis Furuya-Kanamori
- Department of Population Medicine, College of Medicine, Qatar University, Doha, Qatar
| | - Claire L Jeffries
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Mojca Kristan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Abdul Rahim Mohammed
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Korle Bu, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Korle Bu, Accra, Ghana
| | - Kathleen O'Reilly
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Eduardo Massad
- School of Applied Mathematics, Fundacao Getulio Vargas, Rio de Janeiro, Brazil
| | - Chris Drakeley
- Department of Immunology & Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Thomas Walker
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Laith Yakob
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
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44
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Kang SY, Battle KE, Gibson HS, Cooper LV, Maxwell K, Kamya M, Lindsay SW, Dorsey G, Greenhouse B, Rodriguez-Barraquer I, Reiner RCJ, Smith DL, Bisanzio D. Heterogeneous exposure and hotspots for malaria vectors at three study sites in Uganda. Gates Open Res 2018; 2:32. [PMID: 30706054 PMCID: PMC6350504 DOI: 10.12688/gatesopenres.12838.2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2018] [Indexed: 11/30/2022] Open
Abstract
Background: Heterogeneity in malaria transmission has household, temporal, and spatial components. These factors are relevant for improving the efficiency of malaria control by targeting heterogeneity. To quantify variation, we analyzed mosquito counts from entomological surveillance conducted at three study sites in Uganda that varied in malaria transmission intensity. Mosquito biting or exposure is a risk factor for malaria transmission. Methods: Using a Bayesian zero-inflated negative binomial model, validated via a comprehensive simulation study, we quantified household differences in malaria vector density and examined its spatial distribution. We introduced a novel approach for identifying changes in vector abundance hotspots over time by computing the Getis-Ord statistic on ratios of household biting propensities for different scenarios. We also explored the association of household biting propensities with housing and environmental covariates. Results: In each site, there was evidence for hot and cold spots of vector abundance, and spatial patterns associated with urbanicity, elevation, or other environmental covariates. We found some differences in the hotspots in rainy vs. dry seasons or before vs. after the application of control interventions. Housing quality explained a portion of the variation among households in mosquito counts. Conclusion: This work provided an improved understanding of heterogeneity in malaria vector density at the three study sites in Uganda and offered a valuable opportunity for assessing whether interventions could be spatially targeted to be aimed at abundance hotspots which may increase malaria risk. Indoor residual spraying was shown to be a successful measure of vector control interventions in Tororo, Uganda. Cement walls, brick floors, closed eaves, screened airbricks, and tiled roofs were features of a house that had shown reduction of household biting propensity. Improvements in house quality should be recommended as a supplementary measure for malaria control reducing risk of infection.
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Affiliation(s)
- Su Yun Kang
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Katherine E Battle
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Harry S Gibson
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Laura V Cooper
- Department of Veterinary Medicine, Cambridge University, Cambridge, UK
| | - Kilama Maxwell
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Moses Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | | | - Robert C Jr Reiner
- Institute for Health Metrics & Evaluation, University of Washington, Seattle, WA, USA
| | - David L Smith
- Institute for Health Metrics & Evaluation, University of Washington, Seattle, WA, USA
| | - Donal Bisanzio
- RTI International, Washington DC, USA.,Centre for Tropical Diseases, Sacro Cuore-Don Calabria Hospital, Negrar, Italy
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45
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Pires CV, Alves JRS, Lima BAS, Paula RB, Costa HL, Torres LM, Sousa TN, Soares IS, Sanchez BAM, Fontes CJF, Ntumngia FB, Adams JH, Kano FS, Carvalho LH. Blood-stage Plasmodium vivax antibody dynamics in a low transmission setting: A nine year follow-up study in the Amazon region. PLoS One 2018; 13:e0207244. [PMID: 30419071 PMCID: PMC6231651 DOI: 10.1371/journal.pone.0207244] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/26/2018] [Indexed: 11/23/2022] Open
Abstract
Plasmodium vivax remains a global health problem and its ability to cause relapses and subpatent infections challenge control and elimination strategies. Even in low malaria transmission settings, such as the Amazon basin, where progress in malaria control has caused a remarkable reduction in case incidence, a recent increase in P. vivax transmission demonstrates the continued vulnerability of P.vivax-exposed populations. As part of a search for complementary approaches to P.vivax surveillance in areas in which adults are the majority of the exposed-population, here we evaluated the potential of serological markers covering a wide range of immunogenicity to estimate malaria transmission trends. For this, antibodies against leading P. vivax blood-stage vaccine candidates were assessed during a 9 year follow-up study among adults exposed to unstable malaria transmission in the Amazon rainforest. Circulating antibody levels against immunogenic P. vivax proteins, such as the Apical Membrane Antigen-1, were a sensitive measure of recent P. vivax exposure, while antibodies against less immunogenic proteins were indicative of naturally-acquired immunity, including the novel engineered Duffy binding protein II immunogen (DEKnull-2). Our results suggest that the robustness of serology to estimate trends in P.vivax malaria transmission will depend on the immunological background of the study population, and that for adult populations exposed to unstable P.vivax malaria transmission, the local heterogeneity of antibody responses should be considered when considering use of serological surveillance.
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Affiliation(s)
- Camilla V. Pires
- Instituto René Rachou/FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | | | | | - Ruth B. Paula
- Instituto René Rachou/FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | - Helena L. Costa
- Instituto René Rachou/FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | | | - Taís N. Sousa
- Instituto René Rachou/FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
| | - Irene S. Soares
- Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Bruno A. M. Sanchez
- Instituto de Ciências da Saúde, Universidade Federal de Mato Grosso, Campus Sinop, Sinop, Mato Grosso, Brazil
| | - Cor J. F. Fontes
- Hospital Júlio Muller, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso, Brazil
| | - Francis B. Ntumngia
- Center for Global Health and Infectious Diseases Research, Department of Global Health, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - John H. Adams
- Center for Global Health and Infectious Diseases Research, Department of Global Health, College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Flora S. Kano
- Instituto René Rachou/FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
- * E-mail: (LHC); (FSK)
| | - Luzia H. Carvalho
- Instituto René Rachou/FIOCRUZ, Belo Horizonte, Minas Gerais, Brazil
- * E-mail: (LHC); (FSK)
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46
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Kang SY, Battle KE, Gibson HS, Cooper LV, Maxwell K, Kamya M, Lindsay SW, Dorsey G, Greenhouse B, Rodriguez-Barraquer I, Reiner RCJ, Smith DL, Bisanzio D. Heterogeneous exposure and hotspots for malaria vectors at three study sites in Uganda. Gates Open Res 2018. [DOI: 10.12688/gatesopenres.12838.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background: Heterogeneity in malaria transmission has household, temporal, and spatial components. These factors are relevant for improving the efficiency of malaria control by targeting heterogeneity. To quantify variation, we analyzed mosquito counts from entomological surveillance conducted at three study sites in Uganda that varied in malaria transmission intensity. Methods: Using a Bayesian zero-inflated negative binomial model, validated via a comprehensive simulation study, we quantified household differences in malaria vector density and examined its spatial distribution. We introduced a novel approach for identifying changes in malaria hotspots over time by computing the Getis-Ord statistic on ratios of household biting propensities for different scenarios. We also explored the association of household biting propensities with housing and environmental covariates. Results: In each site, there was evidence for hot and cold spots, spatial patterns associated with urbanicity, elevation, or other environmental covariates. We found some differences in the hotspots in rainy vs. dry seasons or before vs. after the application of control interventions. Housing quality explained a portion of the variation among households in mosquito counts. Conclusion: This work provided an improved understanding of heterogeneity in malaria vector density at the three study sites in Uganda and offered a valuable opportunity for assessing whether interventions could be spatially targeted to be aimed at hotspots of malaria risk. Indoor residual spraying was shown to be a successful measure of vector control interventions in Tororo, Uganda. Cement walls, brick floors, closed eaves, screened airbricks, and tiled roofs were features of a house that had shown protective effects towards malaria risk. Improvements in house quality should be recommended as a supplementary measure for malaria control.
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