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Coulibaly ZI, Gowelo S, Traore I, Mbewe RB, Ngulube W, Olanga EA, DePina AJ, Sanou A, Coleman S, Tangena JAA. Strengthening adult mosquito surveillance in Africa for disease control: learning from the present. Curr Opin Insect Sci 2023; 60:101110. [PMID: 37660835 PMCID: PMC7615242 DOI: 10.1016/j.cois.2023.101110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 08/27/2023] [Accepted: 08/29/2023] [Indexed: 09/05/2023]
Abstract
Mosquito surveillance is essential to successfully control and eliminate mosquito-borne diseases. Yet, it is often done by numerous organizations with little collaboration, incomplete understanding of existing gaps, and limited long-term vision. There is a clear disconnect between entomological and epidemiological indices, with entomological data informing control efforts inadequately. Here, we discuss current mosquito surveillance practises across the heterogeneous disease landscape in Africa. We advocate for the development of mosquito surveillance strategic plans to increase the impact and functionality of mosquito surveillance. We urge for a proactive approach to set up centralized mosquito data systems under the custodian of national governments, focus on epidemiologically relevant mosquito data, and increase the robustness of mosquito surveillance using a more spatially explicit sampling design.
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Affiliation(s)
| | - Steve Gowelo
- Malaria Alert centre of the Kamuzu University of Health Sciences, Malawi; University of California San Francisco, Malaria Elimination Initiative, USA
| | | | - Rex B Mbewe
- Malawi University of Business and Applied Sciences, Malawi; Malawi Liverpool Wellcome Trust, Malawi
| | | | - Evelyn A Olanga
- Malaria Alert centre of the Kamuzu University of Health Sciences, Malawi
| | | | - Antoine Sanou
- Centre National de Recherche et de Formation sur le Paludisme, Burkina Faso; Institut Supérieur de Développement Durable, Université de Fada N'Gourma, Burkina Faso
| | - Sylvester Coleman
- Vector Biology department, Liverpool School of Tropical Medicine, United Kingdom
| | - Julie-Anne A Tangena
- Vector Biology department, Liverpool School of Tropical Medicine, United Kingdom.
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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: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [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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Cohee LM, Goupeyou-Youmsi J, Seydel KB, Mangani C, Ntenda P, Sixpence A, Mbewe RB, Matengeni A, Takala-Harrison S, Walker ED, Wilson ML, Mzilahowa T, Laufer MK, Valim C, Taylor TE, Mathanga DP. Understanding the Intransigence of Malaria in Malawi. Am J Trop Med Hyg 2022; 107:40-48. [PMID: 36228915 PMCID: PMC9662216 DOI: 10.4269/ajtmh.21-1263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 03/19/2022] [Indexed: 01/29/2023] Open
Abstract
Despite the scale-up of interventions against malaria over the past decade, this disease remains a leading threat to health in Malawi. To evaluate the epidemiology of both Plasmodium falciparum infection and malaria disease, the Malawi International Center of Excellence for Malaria Research (ICEMR) has developed and implemented diverse and robust surveillance and research projects. Descriptive studies in ICEMR Phase 1 increased our understanding of the declining effectiveness of long-lasting insecticidal nets (LLINs), the role of school-age children in malaria parasite transmission, and the complexity of host-parasite interactions leading to disease. These findings informed the design of ICEMR Phase 2 to test hypotheses about LLIN use and effectiveness, vector resistance to insecticides, demographic targets of malaria control, patterns and causes of asymptomatic to life-threatening disease, and the impacts of RTS,S vaccination plus piperonyl butoxide-treated LLINs on infection and disease in young children. These investigations are helping us to understand mosquito-to-human and human-to-mosquito transmission in the context of Malawi's intransigent malaria problem.
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Affiliation(s)
- Lauren M. Cohee
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | | | - Karl B. Seydel
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan
| | - Charles Mangani
- School of Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Peter Ntenda
- Malaria Alert Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Alick Sixpence
- Malaria Alert Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Rex B. Mbewe
- Department of Physics and Biochemical Sciences, Malawi University of Business and Applied Sciences, Blantyre, Malawi
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan
| | - Alfred Matengeni
- Malaria Alert Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Shannon Takala-Harrison
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Edward D. Walker
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan
| | - Mark L. Wilson
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, Michigan
| | - Themba Mzilahowa
- Malaria Alert Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Miriam K. Laufer
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Clarissa Valim
- Department of Global Health, Boston University School of Public Health, Boston, Massachusetts
| | - Terrie E. Taylor
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan
| | - Don P. Mathanga
- Malaria Alert Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
- School of Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
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Mbewe RB, Keven JB, Mzilahowa T, Mathanga D, Wilson M, Cohee L, Laufer MK, Walker ED. Blood-feeding patterns of Anopheles vectors of human malaria in Malawi: implications for malaria transmission and effectiveness of LLIN interventions. Malar J 2022; 21:67. [PMID: 35241083 PMCID: PMC8892392 DOI: 10.1186/s12936-022-04089-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 02/16/2022] [Indexed: 11/23/2022] Open
Abstract
Background Access to human hosts by Anopheles mosquitoes is a key determinant of vectorial capacity for malaria, but it can be limited by use of long-lasting insecticidal nets (LLINs). In Malawi, pyrethroid-treated LLINs with and without the synergist piperonyl butoxide (PBO) were distributed to control malaria. This study investigated the blood-feeding patterns of malaria vectors and whether LLINs containing pyrethroid and PBO led to a reduction of human blood feeding than those containing only pyrethroids. Methods Mosquitoes were sampled inside houses from May 2019 through April 2020 by aspiration, pyrethrum spray catch, and light trap methods in two sites. One site (Namanolo, Balaka district) had LLINs containing only pyrethroids whereas the other (Ntaja, Machinga district) had LLINs with both pyrethroids and PBO. Anopheles species, their blood-meal host, and infection with Plasmodium falciparum were determined using PCR methods. Results A total of 6585 female Anopheles were sampled in 203 houses. Of these, 633 (9.6%) were blood-fed mosquitoes comprising of 279 (44.1%) Anopheles arabiensis, 103 (16.3%) Anopheles gambiae 212 (33.5), Anopheles funestus, 2 (0.3%), Anopheles parensis and 37 (5.8%) were unidentified Anopheles spp. Blood meal hosts were successfully identified for 85.5% (n = 541) of the blood-fed mosquitoes, of which 436 (81.0%) were human blood meals, 28 (5.2%) were goats, 11 (2.0%) were dogs, 60 (11.1%) were mixed goat-human blood meals, 5 (0.9%) were dog–human, and 1 was a mixed dog-goat. Human blood index (fraction of blood meals that were humans) was significantly higher in Namanolo (0.96) than Ntaja (0.89). Even though human blood index was high, goats were over-selected than humans after accounting for relative abundance of both hosts. The number of infectious Anopheles bites per person-year was 44 in Namanolo and 22 in Ntaja. Conclusion Although LLINs with PBO PBO may have reduced human blood feeding, access to humans was extremely high despite high LLIN ownership and usage rates in both sites. This finding could explain persistently high rates of malaria infections in Malawi. However, this study had one village for each net type, thus the observed differences may have been a result of other factors present in each village. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04089-7.
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Affiliation(s)
- Rex B Mbewe
- Department of Physics and Biochemical Sciences, Polytechnic, University of Malawi, Blantyre, Malawi. .,Department of Entomology, Michigan State University, East Lansing, MI, 48824, USA.
| | - John B Keven
- Department of Entomology, Michigan State University, East Lansing, MI, 48824, USA.,Department of Public Health, University of California-Irvine, Irvine, CA, USA
| | - Themba Mzilahowa
- Malaria Alert Center, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Don Mathanga
- Malaria Alert Center, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Mark Wilson
- Department of Epidemiology, School of Public Health, University of Michigan, Ann Arbor, MI, USA
| | - Lauren Cohee
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Miriam K Laufer
- 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, 48824, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
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Keven JB, Artzberger G, Gillies ML, Mbewe RB, Walker ED. Probe-based multiplex qPCR identifies blood-meal hosts in Anopheles mosquitoes from Papua New Guinea. Parasit Vectors 2020; 13:111. [PMID: 32111232 PMCID: PMC7048118 DOI: 10.1186/s13071-020-3986-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 02/21/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Determination of blood-meal hosts in blood-fed female Anopheles mosquitoes is important for evaluating vectorial capacity of vector populations and assessing effectiveness of vector control measures. Sensitive molecular methods are needed to detect traces of host blood in mosquito samples, to differentiate hosts, and to detect mixed host blood meals. This paper describes a molecular probe-based quantitative PCR for identifying blood-meal hosts in Anopheles malaria vectors from Papua New Guinea. METHODS TaqMan oligonucleotide probes targeting specific regions of mitochondrial or nuclear DNA of the three primary Anopheles blood-meal hosts, humans, pigs and dogs, were incorporated into a multiplex, quantitative PCR which was optimized for sensitivity and specificity. RESULTS Amplification of serially diluted DNA showed that the quantitative PCR detected as low as 10-5 ng/μl of host DNA. Application to field-collected, blood-fed Anopheles showed that the quantitative PCR identified the vertebrate hosts for 89% (335/375) of mosquitoes whereas only 55% (104/188) of blood-meal samples tested in a conventional PCR were identified. Of the 104 blood-fed Anopheles that were positive in both PCR methods, 16 (15.4%) were identified as mixed blood meals by the quantitative PCR whereas only 3 (2.9%) were mixed blood meals by the conventional PCR. CONCLUSIONS The multiplex quantitative PCR described here is sensitive at detecting low DNA concentration and mixed host DNA in samples and useful for blood-meal analysis of field mosquitoes, in particular mixed-host blood meals.
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Affiliation(s)
- John B Keven
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA. .,Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea.
| | - Georgia Artzberger
- Department of Biomedical Laboratory Diagnostics, Michigan State University, East Lansing, MI, USA
| | - Mary L Gillies
- Department of Biomedical Laboratory Diagnostics, Michigan State University, East Lansing, MI, USA
| | - Rex B Mbewe
- Department of Entomology, Michigan State University, East Lansing, MI, USA.,Department of Physics and Biochemical Sciences, University of Malawi, The Polytechnic, Blantyre, Malawi
| | - Edward D Walker
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA.,Department of Entomology, Michigan State University, East Lansing, MI, USA
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Mzilahowa T, Chiumia M, Mbewe RB, Uzalili VT, Luka-Banda M, Kutengule A, Mathanga DP, Ali D, Chiphwanya J, Zoya J, Mulenga S, Dodoli W, Bergeson-Lockwood J, Troell P, Oyugi J, Lindblade K, Gimnig JE. Increasing insecticide resistance in Anopheles funestus and Anopheles arabiensis in Malawi, 2011-2015. Malar J 2016; 15:563. [PMID: 27876046 PMCID: PMC5120501 DOI: 10.1186/s12936-016-1610-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/09/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Susceptibility of principal Anopheles malaria vectors to common insecticides was monitored over a 5-year period across Malawi to inform and guide the national malaria control programme. METHODS Adult blood-fed Anopheles spp. and larvae were collected from multiple sites in sixteen districts across the country between 2011 and 2015. First generation (F1) progeny aged 2-5 days old were tested for susceptibility, using standard WHO procedures, against pyrethroids (permethrin and deltamethrin), carbamates (bendiocarb and propoxur), organophosphates (malathion and pirimiphos-methyl) and an organochlorine (DDT). RESULTS Mortality of Anopheles funestus to deltamethrin, permethrin, bendiocarb and propoxur declined significantly over the 5-year (2011-2015) monitoring period. There was wide variation in susceptibility to DDT but it was not associated with time. In contrast, An. funestus exhibited 100% mortality to the organophosphates (malathion and pirimiphos-methyl) at all sites tested. There was reduced mortality of Anopheles arabiensis to deltamethrin over time though this was not statistically significant. However, mortality of An. arabiensis exposed to permethrin declined significantly over time. Anopheles arabiensis exposed to DDT were more likely to be killed if there was high ITN coverage in the mosquito collection area the previous year. There were no other associations between mosquito mortality in a bioassay and ITN coverage or IRS implementation. Mortality of An. funestus from four sites exposed to deltamethrin alone ranged from 2 to 31% and from 41 to 94% when pre-exposed to the synergist piperonyl butoxide followed by deltamethrin. For permethrin alone, mortality ranged from 2 to 13% while mortality ranged from 63 to 100% when pre-exposed to PBO. CONCLUSION Pyrethroid resistance was detected in An. funestus and An. arabiensis populations across Malawi and has worsened over the last 5 years. New insecticides and control strategies are urgently needed to reduce the burden of malaria in Malawi.
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Affiliation(s)
- Themba Mzilahowa
- Malaria Alert Centre, Malawi College of Medicine, Chichiri, P/Bag 360, Blantyre 3, Malawi.
| | - Martin Chiumia
- Malaria Alert Centre, Malawi College of Medicine, Chichiri, P/Bag 360, Blantyre 3, Malawi
| | - Rex B Mbewe
- Malaria Alert Centre, Malawi College of Medicine, Chichiri, P/Bag 360, Blantyre 3, Malawi
| | - Veronica T Uzalili
- Malaria Alert Centre, Malawi College of Medicine, Chichiri, P/Bag 360, Blantyre 3, Malawi
| | - Madalitso Luka-Banda
- Malaria Alert Centre, Malawi College of Medicine, Chichiri, P/Bag 360, Blantyre 3, Malawi
| | - Anna Kutengule
- Malaria Alert Centre, Malawi College of Medicine, Chichiri, P/Bag 360, Blantyre 3, Malawi
| | - Don P Mathanga
- Malaria Alert Centre, Malawi College of Medicine, Chichiri, P/Bag 360, Blantyre 3, Malawi
| | - Doreen Ali
- Community Health Services Unit, National Malaria Control Programme, Ministry of Health, Lilongwe, Malawi
| | - John Chiphwanya
- Community Health Services Unit, National Malaria Control Programme, Ministry of Health, Lilongwe, Malawi
| | - John Zoya
- Community Health Services Unit, National Malaria Control Programme, Ministry of Health, Lilongwe, Malawi
| | - Shadreck Mulenga
- Community Health Services Unit, National Malaria Control Programme, Ministry of Health, Lilongwe, Malawi
| | | | | | - Peter Troell
- President's Malaria Initiative, Centers for Disease Control and Prevention, Lilongwe, Malawi
| | - Jessica Oyugi
- Division of Parasitic Diseases and Malaria, Centers for Diseases Control and Prevention, Atlanta, GA, USA
| | - Kim Lindblade
- Division of Parasitic Diseases and Malaria, Centers for Diseases Control and Prevention, Atlanta, GA, USA
| | - John E Gimnig
- Division of Parasitic Diseases and Malaria, Centers for Diseases Control and Prevention, Atlanta, GA, USA
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