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Saili K, de Jager C, Masaninga F, Chisanga B, Sinyolo A, Chiwaula J, Chirwa J, Hamainza B, Chanda E, Bakyaita NN, Mutero CM. Community perceptions, acceptability, and the durability of house screening interventions against exposure to malaria vectors in Nyimba district, Zambia. BMC Public Health 2024; 24:285. [PMID: 38267927 PMCID: PMC10809574 DOI: 10.1186/s12889-024-17750-4] [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: 07/22/2023] [Accepted: 01/11/2024] [Indexed: 01/26/2024] Open
Abstract
BACKGROUND House screening remains conspicuously absent in national malaria programs despite its recognition by the World Health Organization as a supplementary malaria vector-control intervention. This may be attributed, in part, to the knowledge gap in screen durability or longevity in local climatic conditions and community acceptance under specific cultural practices and socio-economic contexts. The objectives of this study were to assess the durability of window and door wire mesh screens a year after full house screening and to assess the acceptability of the house screening intervention to the participants involved. METHODS This study was conducted in Nyimba district, Zambia and used both quantitative and qualitative methods of data collection and analysis. Both direct observation and questionnaires were employed to assess the durability of the screens and the main reasons for damage. Findings on damage were summarized as percentages. Focus group discussions were used to assess people's knowledge, perceptions, and acceptability of the closing eaves and house screening intervention. Deductive coding and inductive coding were used to analyse the qualitative data. RESULTS A total of 321 out of 400 (80.3%) household owners of screened houses were interviewed. Many window screens (90.3%) were intact. In sharp contrast, most door screens were torn (n = 150; 46.7%) or entirely removed (n = 55; 17.1%). Most doors (n = 114; 76%) had their wire mesh damaged or removed on the bottom half. Goats (25.4%), rust (17.6%) and children (17.1%) were cited most as the cause of damage to door screens. The focus group discussion elicited positive experiences from the participants following the closing of eaves and screening of their windows and doors, ranging from sleeping peacefully due to reduced mosquito biting and/or nuisance and having fewer insects in the house. Participants linked house screening to reduced malaria in their households and community. CONCLUSION This study demonstrated that in rural south-east Zambia, closing eaves and screening windows and doors was widely accepted. Participants perceived that house screening reduced human-vector contact, reduced the malaria burden and nuisance biting from other potentially disease carrying insects. However, screened doors are prone to damage, mainly by children, domestic animals, rust, and termites.
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Affiliation(s)
- Kochelani Saili
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, P.O. Box 30772-00100, Kenya.
- School of Health Systems & Public Health, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa.
| | - Christiaan de Jager
- School of Health Systems & Public Health, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | | | - Brian Chisanga
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, P.O. Box 30772-00100, Kenya
- Development Economics Group, Wageningen University and Research, Wageningen, Netherlands
| | - Andy Sinyolo
- National Malaria Elimination Centre, Lusaka, Zambia
| | | | - Jacob Chirwa
- National Malaria Elimination Centre, Lusaka, Zambia
| | | | - Emmanuel Chanda
- World Health Organization, Regional Office, Brazzaville, Congo
| | | | - Clifford Maina Mutero
- International Centre of Insect Physiology and Ecology (icipe), Nairobi, P.O. Box 30772-00100, Kenya
- School of Health Systems & Public Health, University of Pretoria Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
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Máquina M, Opiyo MA, Cuamba N, Marrenjo D, Rodrigues M, Armando S, Nhate S, Luis F, Saúte F, Candrinho B, Lobo NF, Paaijmans KP. Multiple Anopheles species complicate downstream analysis and decision-making in a malaria pre-elimination area in southern Mozambique. Malar J 2024; 23:23. [PMID: 38238774 PMCID: PMC10797956 DOI: 10.1186/s12936-024-04842-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/05/2024] [Indexed: 01/22/2024] Open
Abstract
BACKGROUND Different anopheline species (even within a species group/complex) can differ in their feeding and resting behaviours, which impact both malaria transmission patterns as well as the efficacy of vector control interventions. While morphological identification of sampled specimens is an important first step towards understanding species diversity and abundance, misidentification can result in the implementation of less effective vector control measures, and consequently smaller reductions in the number of local malaria cases. Focusing on southern Mozambique, a malaria pre-elimination area where malaria remains persistent, the aims of this preliminary study were to use molecular identification (CO1 and ITS2 barcoding) to (1) validate the results from the morphological identification (with a particular focus on Anopheles pharoensis and Anopheles squamosus), and (2) have a closer look at the Anopheles coustani group (which includes Anopheles tenebrosus and Anopheles ziemanni). METHODS Female anopheline mosquitoes (n = 81) were identified morphologically and subsequently sequenced at the ribosomal DNA internal transcribed spacer region 2 (ITS2) and/or cytochrome oxidase subunit 1 (CO1) loci towards species determination. RESULTS Out of the 62 specimens that were identified morphologically to species, 4 (6.5%) were misidentified. Regarding the An. coustani group, morphological identification showed that several members are present in southern Mozambique, including An. coustani sensu lato (s.l.), An. ziemanni and An. tenebrosus. However, based on both ITS2 and CO1 sequences, the exact species remains unknown for the latter two members until voucher sequences are available for comparison. CONCLUSION The reason(s) for morphological misidentification of anopheline mosquitoes need to be mitigated. This is usually related to both the capacity (i.e. training) of the microscopist to identify anopheline species, and the information provided in the dichotomous identification key. As the An. coustani complex contributes to (residual) malaria transmission in sub-Saharan Africa, it may play a role in the observed persistent malaria in southern Mozambique. A better baseline characterizing of the local anophelines species diversity and behaviours will allow us to improve entomological surveillance strategies, better understand the impact of vector control on each local vector species, and identify new approaches to target those vector species.
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Affiliation(s)
- Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Mercy A Opiyo
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
- ISGlobal, Barcelona, Spain
- Malaria Elimination Initiative, University of California San Francisco, San Francisco, CA, USA
| | - Nelson Cuamba
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Dulcisária Marrenjo
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
| | | | | | - Sheila Nhate
- Maputo Provincial Health Service, Matola, Mozambique
| | - Fabião Luis
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique
| | - Baltazar Candrinho
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
| | - Neil F Lobo
- Malaria Elimination Initiative, University of California San Francisco, San Francisco, CA, USA
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Krijn P Paaijmans
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Manhica, Mozambique.
- ISGlobal, Barcelona, Spain.
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA.
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA.
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Saili K, de Jager C, Masaninga F, Sangoro OP, Nkya TE, Likulunga LE, Chirwa J, Hamainza B, Chanda E, Fillinger U, Mutero CM. House Screening Reduces Exposure to Indoor Host-Seeking and Biting Malaria Vectors: Evidence from Rural South-East Zambia. Trop Med Infect Dis 2024; 9:20. [PMID: 38251217 PMCID: PMC10821011 DOI: 10.3390/tropicalmed9010020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 12/31/2023] [Accepted: 01/09/2024] [Indexed: 01/23/2024] Open
Abstract
This study evaluated the impact of combining house screens with long-lasting insecticidal nets (LLINs) on mosquito host-seeking, resting, and biting behavior. Intervention houses received house screens and LLINs, while control houses received only LLINs. Centre for Disease Control light traps, pyrethrum spray collections and human landing catches were used to assess the densities of indoor and outdoor host-seeking, indoor resting, and biting behavior of malaria vectors in 15 sentinel houses per study arm per sampling method. The protective efficacy of screens and LLINs was estimated through entomological inoculation rates (EIRs). There were 68% fewer indoor host-seeking Anopheles funestus (RR = 0.32, 95% CI 0.20-0.51, p < 0.05) and 63% fewer An. arabiensis (RR = 0.37, 95% CI 0.22-0.61, p < 0.05) in screened houses than unscreened houses. There was a significantly higher indoor biting rate for unscreened houses (6.75 bites/person/h [b/p/h]) than for screened houses (0 b/p/h) (χ2 = 6.67, df = 1, p < 0.05). The estimated indoor EIR in unscreened houses was 2.91 infectious bites/person/six months, higher than that in screened houses (1.88 infectious bites/person/six months). Closing eaves and screening doors and windows has the potential to reduce indoor densities of malaria vectors and malaria transmission.
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Affiliation(s)
- Kochelani Saili
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (O.P.S.); (T.E.N.); (U.F.); (C.M.M.)
- University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems & Public Health, University of Pretoria, Pretoria 0028, South Africa;
| | - Christiaan de Jager
- University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems & Public Health, University of Pretoria, Pretoria 0028, South Africa;
| | - Freddie Masaninga
- Country Office, World Health Organization, P.O. Box 32346, Lusaka 10101, Zambia;
| | - Onyango P. Sangoro
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (O.P.S.); (T.E.N.); (U.F.); (C.M.M.)
| | - Theresia E. Nkya
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (O.P.S.); (T.E.N.); (U.F.); (C.M.M.)
- Mbeya College of Health and Allied Sciences, University of Dar es Salaam, Mbeya 35063, Tanzania
| | - Likulunga Emmanuel Likulunga
- Department of Biological Sciences, University of Zambia, Great East Road Campus, P.O. Box 32379, Lusaka 10101, Zambia;
| | - Jacob Chirwa
- National Malaria Elimination Centre, P.O. Box 32509, Lusaka 10101, Zambia; (J.C.); (B.H.)
| | - Busiku Hamainza
- National Malaria Elimination Centre, P.O. Box 32509, Lusaka 10101, Zambia; (J.C.); (B.H.)
| | - Emmanuel Chanda
- WHO Regional Office for Africa, Cite du Djoue, Brazzaville P.O. Box 06, Congo
| | - Ulrike Fillinger
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (O.P.S.); (T.E.N.); (U.F.); (C.M.M.)
| | - Clifford Maina Mutero
- International Centre of Insect Physiology and Ecology (icipe), Nairobi P.O. Box 30772-00100, Kenya; (O.P.S.); (T.E.N.); (U.F.); (C.M.M.)
- University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems & Public Health, University of Pretoria, Pretoria 0028, South Africa;
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Msugupakulya BJ, Urio NH, Jumanne M, Ngowo HS, Selvaraj P, Okumu FO, Wilson AL. Changes in contributions of different Anopheles vector species to malaria transmission in east and southern Africa from 2000 to 2022. Parasit Vectors 2023; 16:408. [PMID: 37936155 PMCID: PMC10631025 DOI: 10.1186/s13071-023-06019-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/18/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Malaria transmission in Africa is facilitated by multiple species of Anopheles mosquitoes. These vectors have different behaviors and vectorial capacities and are affected differently by vector control interventions, such as insecticide-treated nets and indoor residual spraying. This review aimed to assess changes in the contribution of different vector species to malaria transmission in east and southern Africa over 20 years of widespread insecticide-based vector control. METHODS We searched PubMed, Global Health, and Web of Science online databases for articles published between January 2000 and April 2023 that provided species-specific sporozoite rates for different malaria vectors in east and southern Africa. We extracted data on study characteristics, biting rates, sporozoite infection proportions, and entomological inoculation rates (EIR). Using EIR data, the proportional contribution of each species to malaria transmission was estimated. RESULTS Studies conducted between 2000 and 2010 identified the Anopheles gambiae complex as the primary malaria vector, while studies conducted from 2011 to 2021 indicated the dominance of Anopheles funestus. From 2000 to 2010, in 57% of sites, An. gambiae demonstrated higher parasite infection prevalence than other Anopheles species. Anopheles gambiae also accounted for over 50% of EIR in 76% of the study sites. Conversely, from 2011 to 2021, An. funestus dominated with higher infection rates than other Anopheles in 58% of sites and a majority EIR contribution in 63% of sites. This trend coincided with a decline in overall EIR and the proportion of sporozoite-infected An. gambiae. The main vectors in the An. gambiae complex in the region were Anopheles arabiensis and An. gambiae sensu stricto (s.s.), while the important member of the An. funestus group was An. funestus s.s. CONCLUSION The contribution of different vector species in malaria transmission has changed over the past 20 years. As the role of An. gambiae has declined, An. funestus now appears to be dominant in most settings in east and southern Africa. Other secondary vector species may play minor roles in specific localities. To improve malaria control in the region, vector control should be optimized to match these entomological trends, considering the different ecologies and behaviors of the dominant vector species.
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Affiliation(s)
- Betwel J Msugupakulya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
| | - Naomi H Urio
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania
| | - Mohammed Jumanne
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK
| | - Prashanth Selvaraj
- Institute for Disease Modeling, Bill and Melinda Gates Foundation, Seattle, USA
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- School of Life Science and Bioengineering, The Nelson Mandela African Institution of Sciences & Technology, Arusha, Tanzania.
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, Glasgow, UK.
- School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Park Town, Johannesburg, Republic of South Africa.
| | - Anne L Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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Gueye A, Ngom EHM, Diagne A, Ndoye BB, Dione ML, Sambe BS, Sokhna C, Diallo M, Niang M, Dia I. Host feeding preferences of malaria vectors in an area of low malaria transmission. Sci Rep 2023; 13:16410. [PMID: 37775717 PMCID: PMC10542387 DOI: 10.1038/s41598-023-43761-z] [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: 06/28/2023] [Accepted: 09/28/2023] [Indexed: 10/01/2023] Open
Abstract
Studying the behaviour and trophic preferences of mosquitoes is an important step in understanding the exposure of vertebrate hosts to vector-borne diseases. In the case of human malaria, transmission increases when mosquitoes feed more on humans than on other animals. Therefore, understanding the spatio-temporal dynamics of vectors and their feeding preferences is essential for improving vector control measures. In this study, we investigated the feeding behaviour of Anopheles mosquitoes at two sites in the Sudanian areas of Senegal where transmission is low following the implementation of vector control measures. Blood-fed mosquitoes were collected monthly from July to November 2022 by pyrethrum spray catches in sleeping rooms of almost all houses in Dielmo and Ndiop villages, and blood meals were identified as from human, bovine, ovine, equine and chicken by ELISA. Species from the An. gambiae complex were identified by PCR. The types and numbers of potential domestic animal hosts were recorded in each village. The Human Blood Index (HBI) and the Manly Selection Ratio (MSR) were calculated to determine whether hosts were selected in proportion to their abundance. Spatio-temporal variation in HBI was examined using the Moran's index. A total of 1251 endophilic Anopheles females were collected in 115 bedrooms, including 864 blood fed females of 6 species. An. arabiensis and An. funestus were predominant in Dielmo and Ndiop, respectively. Of the 864 blood meals tested, 853 gave a single host positive result mainly on bovine, equine, human, ovine and chicken in decreasing order in both villages. Overall, these hosts were not selected in proportion to their abundance. The human host was under-selected, highlighting a marked zoophily for the vectors. Over time and space, the HBI were low with no obvious trend, with higher and lower values observed in each of the five months at different points in each village. These results highlight the zoophilic and exophagic behaviour of malaria vectors. This behaviour is likely to be a consequence of the distribution and use of LLINs in both villages and may increase risk of residual outdoor transmission. This underlines the need to study the feeding host profile of outdoor resting populations and how domestic animals may influence malaria epidemiology in order to tailor effective malaria vector control strategies in the two villages.
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Affiliation(s)
- Assiyatou Gueye
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - El Hadji Malick Ngom
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Aissatou Diagne
- Pole Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Baye Bado Ndoye
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Mamadou Lamine Dione
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Babacar Souleymane Sambe
- Pole Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Cheikh Sokhna
- UMR Vecteurs Infections Tropicales et Mediterraneennes (VITROME), Campus International UCAD-IRD, Route des Peres Maristes, BP 1386, Dakar, Senegal
| | - Mawlouth Diallo
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Makhtar Niang
- Pole Immunophysiopathologie et Maladies Infectieuses, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Ibrahima Dia
- Pole de Zoologie Medicale, Institut Pasteur de Dakar, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
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