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Messenger LA, Furnival-Adams J, Chan K, Pelloquin B, Paris L, Rowland M. Vector control for malaria prevention during humanitarian emergencies: a systematic review and meta-analysis. Lancet Glob Health 2023; 11:e534-e545. [PMID: 36925174 DOI: 10.1016/s2214-109x(23)00044-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 01/08/2023] [Accepted: 01/13/2023] [Indexed: 03/15/2023]
Abstract
BACKGROUND Humanitarian emergencies can lead to population displacement, food insecurity, severe health system disruptions, and malaria epidemics among individuals who are immunologically naive. We aimed to assess the impact of different vector control interventions on malaria disease burden during humanitarian emergencies. METHODS In this systematic review and meta-analysis, we searched ten electronic databases and two clinical trial registries from database inception to Oct 19, 2020, with no restrictions on language or study design. We also searched grey literature from 59 stakeholders. Studies were eligible if the population was affected by a humanitarian emergency in a malaria endemic region. We included studies assessing any vector control intervention and in which the primary outcome of interest was malaria infection risk. Reviewers (LAM, JF-A, KC, BP, and LP) independently extracted information from eligible studies, without masking of author or publication, into a database. We did random-effects meta-analyses to calculate pooled risk ratios (RRs) for randomised controlled trials, odds ratios (ORs) for dichotomous outcomes, and incidence rate ratios (IRR) for clinical malaria in non-randomised studies. Certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. This study is registered with PROSPERO, CRD42020214961. FINDINGS Of 12 475 studies screened, 22 studies were eligible for inclusion in our meta-analysis. All studies were conducted between Sept 1, 1989, and Dec 31, 2018, in chronic emergencies, with 616 611 participants from nine countries, evaluating seven different vector control interventions. Insecticide-treated nets significantly decreased Plasmodium falciparum incidence (RR 0·55 [95% CI 0·37-0·79]; high certainty) and Plasmodium vivax incidence (RR 0·69 [0·51-0·94]; high certainty). Evidence for an effect of indoor residual spraying on P falciparum (IRR 0·57 [95% CI 0·53-0·61]) and P vivax (IRR 0·51 [0·49-0·52]) incidence was of very low certainty. Topical repellents were associated with reductions in malaria infection (RR 0·58 [0·35-0·97]; moderate certainty). Moderate-to-high certainty evidence for an effect of insecticide-treated chaddars (equivalent to shawls or blankets) and insecticide-treated cattle on malaria outcomes was evident in some emergency settings. There was very low certainty evidence for the effect of insecticide-treated clothing. INTERPRETATION Study findings strengthen and support WHO policy recommendations to deploy insecticide-treated nets during chronic humanitarian emergencies. There is an urgent need to evaluate and adopt novel interventions for malaria control in the acute phase of humanitarian emergencies. FUNDING WHO Global Malaria Programme.
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Affiliation(s)
- Louisa A Messenger
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK; Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, NV, USA.
| | - Joanna Furnival-Adams
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK; ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Kallista Chan
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Bethanie Pelloquin
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK; School of Tropical Medicine and Global Health, University of Nagasaki, Nagasaki, Japan
| | | | - Mark Rowland
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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Azizi S, Matowo J, Mbewe NJ, Protopopoff N, Athumani R, Matiku W, Shayo M, Tenu F, Rowland M, Mosha F, Kitau J. Laboratory and semi-field efficacy evaluation of permethrin-piperonyl butoxide treated blankets against pyrethroid-resistant malaria vectors. Sci Rep 2022; 12:22166. [PMID: 36550139 PMCID: PMC9774072 DOI: 10.1038/s41598-022-26804-9] [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] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
To control pyrethroid-resistant malaria vectors, Indoor Residual Spraying (IRS) and Long-Lasting Insecticidal Nets (LLINs) that include additional ingredients to pyrethroid are being developed. Same progress needs to be made to the pyrethroid-treated blankets, which are more compatible with shelter structures found in emergency settings such as displaced populations. In the current study, efficacy of blankets treated with permethrin and piperonyl butoxide (PBO) was evaluated against pyrethroid-resistant Anopheles gambiae sensu stricto. Efficacy was compared with that of Olyset LLIN, Olyset Plus LLIN and untreated blanket in terms of mortality and blood-feeding inhibition against pyrethroid-resistant Anopheles gambiae mosquitoes. The current study indicates that, in emergency shelters such as migrant and refugee camps where LLINs cannot be used, PBO-permethrin blankets may provide protection against resistant mosquitoes if widely used. No side effects related to the use of the treated blankets were reported from the participants. These results need validation in a large-scale field trial to assess the epidemiological impact of the intervention, durability and acceptability of this new vector control strategy for malaria vector control.
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Affiliation(s)
- Salum Azizi
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania.
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania.
| | - Johnson Matowo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Njelembo Joshua Mbewe
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Natacha Protopopoff
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Rashid Athumani
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Wambura Matiku
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Magreth Shayo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Filemoni Tenu
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Mark Rowland
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
- Department of Disease Control, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Franklin Mosha
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- Pan African Malaria Vector Research Consortium (PAMVERC), Moshi, Tanzania
| | - Jovin Kitau
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- World Health Organization, Country Office, P.O. Box 9292, Dar es Salaam, Tanzania
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Fernandez Montoya L, Alafo C, Martí-Soler H, Máquina M, Comiche K, Cuamba I, Munguambe K, Cator L, Aide P, Galatas B, Cuamba N, Marrenjo D, Saúte F, Paaijmans KP. Overlaying human and mosquito behavioral data to estimate residual exposure to host-seeking mosquitoes and the protection of bednets in a malaria elimination setting where indoor residual spraying and nets were deployed together. PLoS One 2022; 17:e0270882. [PMID: 36107865 PMCID: PMC9477321 DOI: 10.1371/journal.pone.0270882] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 06/21/2022] [Indexed: 11/18/2022] Open
Abstract
Characterizing persistent malaria transmission that occurs after the combined deployment of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) is critical to guide malaria control and elimination efforts. This requires a detailed understanding of both human and vector behaviors at the same temporal and spatial scale. Cross-sectional human behavior evaluations and mosquito collections were performed in parallel in Magude district, Mozambique. Net use and the exact time when participant moved into each of five environments (outdoor, indoor before bed, indoor in bed, indoor after getting up, and outdoor after getting up) were recorded for individuals from three different age groups and both sexes during a dry and a rainy season. Malaria mosquitoes were collected with CDC light traps in combination with collection bottle rotators. The percentage of residual exposure to host-seeking vectors that occurred in each environment was calculated for five local malaria vectors with different biting behaviors, and the actual (at observed levels of LLIN use) and potential (i.e. if all residents had used an LLIN) personal protection conferred by LLINs was estimated. Anopheles arabiensis was responsible for more than 74% of residents' residual exposure to host-seeking vectors during the Magude project. The other four vector species (An. funestus s.s., An. parensis, An. squamosus and An. merus) were responsible for less than 10% each. The personal protection conferred by LLINs prevented only 39.2% of the exposure to host-seeking vectors that survived the implementation of both IRS and LLINs, and it differed significantly across seasons, vector species and age groups. At the observed levels of bednet use, 12.5% of all residual exposure to host-seeking vectors occurred outdoor during the evening, 21.9% indoor before going to bed, almost two thirds (64%) while people were in bed, 1.4% indoors after getting up and 0.2% outdoor after leaving the house. Almost a third of the residual exposure to host-seeking vectors (32.4%) occurred during the low transmission season. The residual bites of An. funestus s.s. and An. parensis outdoors and indoor before bedtime, of An. arabiensis indoors when people are in bed, and of An. squamosus both indoors and outdoors, are likely to have sustained malaria transmission throughout the Magude project. By increasing LLIN use, an additional 24.1% of exposure to the remaining hosts-seeking vectors could have been prevented. Since An. arabiensis, the most abundant vector, feeds primarily while people are in bed, increasing net use and net feeding inhibition (through e.g. community awareness activities and the selection of more effective LLINs) could significantly reduce the exposure to remaining host-seeking mosquitoes. Nonetheless, supplementary interventions aiming to reduce human-vector contact outdoors and/or indoors before people go to bed (e.g. through larval source management, window and eave screening, eave tubes, and spatial repellents) will be needed to reduce residual exposure to the outdoor and early biting An. funestus s.s. and An. parensis.
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Affiliation(s)
- Lucia Fernandez Montoya
- ISGlobal, Hospital Clínic—Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
| | - Celso Alafo
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
- Goodbye Malaria, Tchau Tchau Malaria Foundation, Chibungo, Mozambique
| | | | - Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
| | - Kiba Comiche
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
| | - Inocencia Cuamba
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
| | - Khatia Munguambe
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
| | | | - Pedro Aide
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
- Instituto Nacional da Saúde, Ministério da Saúde, Maputo, Mozambique
| | - Beatriz Galatas
- ISGlobal, Hospital Clínic—Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
| | - Nelson Cuamba
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Dulcisaria Marrenjo
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
| | - Krijn P. Paaijmans
- ISGlobal, Hospital Clínic—Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Mozambique
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, United States of America
- The Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Tempe, AZ, United States of America
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, United States of America
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Nguyen TT, Nguyen XX, Wilson-Barthes M, Sawada I, Muela J, Hausmann-Muela S, Pham TV, Van Nguyen H, Van Nguyen V, Tran DT, Gryseels C, D'Alessandro U, Grietens KP, Erhart A. Why using bed nets is a challenge among minority populations in Central Vietnam. Malar J 2022; 21:87. [PMID: 35292018 PMCID: PMC8922825 DOI: 10.1186/s12936-022-04114-9] [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: 08/10/2021] [Accepted: 03/02/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Despite freely distributed insecticide-treated nets (ITNs) and health information campaigns to increase their use among populations at risk, malaria transmission persists in forested areas in Vietnam, especially among ethnic minority communities. A mixed-methods study was conducted in four villages of Ca Dong and M'nong ethnicity in Central Vietnam between 2009 and 2011 to assess factors limiting the uptake of ITNs. METHODS The mixed-methods research design consisted of a qualitative study to explore the context and barriers to ITN use, and a cross-sectional household survey (n = 141) to quantify factors for limited and appropriate net use. RESULTS The Ca Dong and M'nong's livelihood was dependent on swidden farming in the forest. Poverty-related factors, including the lack of beds, blankets, the practice of sleeping around the kitchen fire and deteriorated ITNs due to open housing structures, were reasons for alternative and non-use of ITNs. When household members stayed overnight in plot huts at fields, ITNs were even more unavailable and easily deteriorated. 72.5% of households reported having received one net for every two persons, and 82.2% of participants reported to have used ITNs the night before the survey. However, only 18.4% of participants were estimated to be effectively protected by ITNs after accounting for the availability of torn ITNs and the way ITNs were used, for example as blankets, at both village and fields. Multi-variable logistic regression showed the effect of four significant factors for appropriate ITN use: i) being female (AOR = 8.08; p = 0.009); ii) aware of mosquito bites as the sole cause of malaria (AOR = 7.43; p = 0.008); iii) not sleeping around the kitchen fire (AOR = 24.57; p = 0.001); and iv) having sufficient number of ITNs in the household (AOR = 21.69; p = 0.001). CONCLUSION This study showed how social factors rooted in poverty and swidden agriculture limited the effective use of ITNs, despite high coverage, among ethnic minority populations in Central Vietnam. An in-depth understanding of the local context is essential to develop specific indicators for measuring ITN use.
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Affiliation(s)
- Thuan Thi Nguyen
- Socio-Ecological Health Research Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium. .,National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam.
| | - Xa Xuan Nguyen
- National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam
| | - Marta Wilson-Barthes
- International Health Institute, Brown University School of Public Health, Providence, USA
| | - Ikumi Sawada
- Department of Clinical Tropical Medicine, Institute of Tropical Medicine, Graduate School of Biomedical Science, Nagasaki University, Nagasaki, Japan
| | - Joan Muela
- University Ramon I Virgili, Tarragona, Spain.,Partners for Applied Social Sciences, PASS International, Tessenderlo, Belgium
| | | | - Thanh Vinh Pham
- National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam
| | - Hong Van Nguyen
- National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam
| | | | - Duong Thanh Tran
- National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam
| | - Charlotte Gryseels
- Socio-Ecological Health Research Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Koen Peeters Grietens
- Socio-Ecological Health Research Unit, Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.,Partners for Applied Social Sciences, PASS International, Tessenderlo, Belgium.,School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Annette Erhart
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
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Messenger LA, Furnival-Adams J, Pelloquin B, Rowland M. Vector control for malaria prevention during humanitarian emergencies: protocol for a systematic review and meta-analysis. BMJ Open 2021; 11:e046325. [PMID: 34315791 PMCID: PMC8317076 DOI: 10.1136/bmjopen-2020-046325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
INTRODUCTION Humanitarian emergencies, of either natural or anthropogenic origins, are equivalent to major disasters, which can lead to population displacement, food insecurity and health system disruptions. Almost two-thirds of people affected by humanitarian emergencies inhabit malaria endemic regions, particularly the WHO African Region, which currently accounts for 93% and 94% of malaria cases and deaths, respectively. As of late 2020, the United Nations Refugee Agency estimates that there are globally 79.5 million forcibly displaced people, including 45.7 million internally displaced people, 26 million refugees, 4.2 million asylum-seekers and 3.6 million Venezuelans displaced abroad. METHODS AND ANALYSES A systematic review and meta-analysis will be conducted to evaluate the impact of different vector control interventions on malaria disease burden during humanitarian emergencies. Published and grey literatures will be systematically retrieved from 10 electronic databases and 3 clinical trials registries. A systematic approach to screening, reviewing and data extraction will be applied based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Two review authors will independently assess full-text copies of potentially relevant articles based on inclusion criteria. Included studies will be assessed for risk of bias according to Cochrane and certainty of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Eligible studies with reported or measurable risk ratios or ORs with 95% CIs will be included in a meta-analysis. Subgroup analyses, including per study design, emergency phase and primary mode of intervention, may be performed if substantial heterogeneity is encountered. ETHICS AND DISSEMINATION Ethical approval is not required by the London School of Hygiene and Tropical Medicine to perform secondary analyses of existing anonymous data. Study findings will be disseminated via open-access publications in peer-reviewed journals, presentations to stakeholders and international policy makers, and will contribute to the latest WHO guidelines for malaria control during humanitarian emergencies. PROSPERO REGISTRATION NUMBER CRD42020214961.
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Affiliation(s)
| | | | - Bethanie Pelloquin
- Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Mark Rowland
- Disease Control, London School of Hygiene & Tropical Medicine, London, UK
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Rocha EM, Katak RDM, Campos de Oliveira J, Araujo MDS, Carlos BC, Galizi R, Tripet F, Marinotti O, Souza-Neto JA. Vector-Focused Approaches to Curb Malaria Transmission in the Brazilian Amazon: An Overview of Current and Future Challenges and Strategies. Trop Med Infect Dis 2020; 5:E161. [PMID: 33092228 PMCID: PMC7709627 DOI: 10.3390/tropicalmed5040161] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/10/2020] [Accepted: 10/13/2020] [Indexed: 01/05/2023] Open
Abstract
In Brazil, malaria transmission is mostly confined to the Amazon, where substantial progress has been made towards disease control in the past decade. Vector control has been historically considered a fundamental part of the main malaria control programs implemented in Brazil. However, the conventional vector-control tools have been insufficient to control or eliminate local vector populations due to the complexity of the Amazonian rainforest environment and ecological features of malaria vector species in the Amazon, especially Anopheles darlingi. Malaria elimination in Brazil and worldwide eradication will require a combination of conventional and new approaches that takes into account the regional specificities of vector populations and malaria transmission dynamics. Here we present an overview on both conventional and novel promising vector-focused tools to curb malaria transmission in the Brazilian Amazon. If well designed and employed, vector-based approaches may improve the implementation of malaria-control programs, particularly in remote or difficult-to-access areas and in regions where existing interventions have been unable to eliminate disease transmission. However, much effort still has to be put into research expanding the knowledge of neotropical malaria vectors to set the steppingstones for the optimization of conventional and development of innovative vector-control tools.
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Affiliation(s)
- Elerson Matos Rocha
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Ricardo de Melo Katak
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Juan Campos de Oliveira
- Programa de Pós-Graduação em Biotecnologia, Universidade Federal do Amazonas—PPGBIOTEC/UFAM, Manaus 69067-005, Brazil; (E.M.R.); (R.d.M.K.); (J.C.d.O.)
| | - Maisa da Silva Araujo
- Laboratory of Medical Entomology, Oswaldo Cruz Foundation, FIOCRUZ RONDONIA, Porto Velho, RO 76812-245, Brazil;
| | - Bianca Cechetto Carlos
- Department of Bioprocesses and Biotechnology, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil;
- Central Multiuser Laboratory, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil
| | - Roberto Galizi
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire ST5 5GB, UK; (R.G.); (F.T.)
| | - Frederic Tripet
- Centre of Applied Entomology and Parasitology, School of Life Sciences, Keele University, Staffordshire ST5 5GB, UK; (R.G.); (F.T.)
| | | | - Jayme A. Souza-Neto
- Department of Bioprocesses and Biotechnology, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil;
- Central Multiuser Laboratory, School of Agricultural Sciences, São Paulo State University (UNESP), Botucatu 18610-034, Brazil
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Gopalakrishnan R, Mazumder A, Yadav R, Meher D, Singh R, Sukumaran D, Thakare VB, Palit M. Comparative evaluation of an improved test method for bioefficacy of insecticidal fabrics against dengue and malaria vectors. Parasit Vectors 2019; 12:375. [PMID: 31358045 PMCID: PMC6664487 DOI: 10.1186/s13071-019-3637-y] [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: 04/05/2019] [Accepted: 07/25/2019] [Indexed: 11/24/2022] Open
Abstract
Background Insecticidal fabrics are important personal protective measures against mosquitoes, ticks and other disease vectors. In the absence of internationally accepted guidelines, bioefficacy tests have been carried out using continuous exposure and three minutes exposure bioassay methods. Recently, we have reported an improved method for bioefficacy testing of insecticidal fabrics, which involves continuous exposure of mosquitoes to the test fabrics. The present paper reports the comparative evaluation of the outcomes of the continuous exposure bioassay and the three minutes bioassay on the same fabric samples. Methods Permethrin content in the treated fabric samples was determined through HPLC analysis and NMR studies were performed to establish the stability of the analyte. Bioefficacy tests were carried out against dengue vector Aedes aegypti and malaria vector Anopheles stephensi as per the improved test method and the three minutes bioassay method. Results The permethrin doses in the fabric samples ranged from 60 to 3000 mg/m2 and 36.2% of permethrin was retained after 10 washings. The extraction and chromatographic analysis were not found to affect the stability of permethrin. In continuous exposure, all fabric samples showed bioefficacy, as the mean complete knockdown time for both Ae. aegypti (10.5–34.5 min) and An. stephensi (14.5–36.8 min) was ≤ 71.5 min. The same samples were found to be not effective when tested using the three minutes bioassay method, since the knockdown and mortality percentages were well below the required bioefficacy values. The bioefficacy of the fabric samples in terms of complete knockdown time was significantly higher against Ae. aegypti in comparison to An. stephensi. The mean complete knockdown time of Ae. aegypti increased to 48.3 min after 10 washings indicating a significant reduction in bioefficacy. Conclusions Bioefficacy testing of the insecticidal fabrics using the improved method resulted in outcomes, which could be correlated better with the permethrin content in the fabric samples. The improved method is more appropriate for the testing of insecticidal fabrics than the three minutes bioassay method. Further evaluation of the improved method using different test arthropods could help in the formulation of specific guidelines for the bioefficacy testing of insecticidal fabrics.
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Affiliation(s)
| | - Avik Mazumder
- Defence Research & Development Establishment, Gwalior, 474002, India
| | - Ruchi Yadav
- Defence Research & Development Establishment, Gwalior, 474002, India
| | - Damayanti Meher
- Defence Research & Development Establishment, Gwalior, 474002, India
| | - Ram Singh
- Defence Research & Development Establishment, Gwalior, 474002, India
| | | | - Vikas B Thakare
- Defence Research & Development Establishment, Gwalior, 474002, India
| | - Meehir Palit
- Defence Research & Development Establishment, Gwalior, 474002, India
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Kröber T, Koussis K, Bourquin M, Tsitoura P, Konstantopoulou M, Awolola TS, Dani FR, Qiao H, Pelosi P, Iatrou K, Guerin PM. Odorant-binding protein-based identification of natural spatial repellents for the African malaria mosquito Anopheles gambiae. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 96:36-50. [PMID: 29656020 DOI: 10.1016/j.ibmb.2018.03.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 02/22/2018] [Accepted: 03/29/2018] [Indexed: 06/08/2023]
Abstract
There is increasing interest in the development of effective mosquito repellents of natural origin to reduce transmission of diseases such as malaria and yellow fever. To achieve this we have employed an in vitro competition assay involving odorant-binding proteins (OBPs) of the malaria mosquito, Anopheles gambiae, with a predominantly female expression bias to identify plant essential oils (EOs) containing bioactive compounds that target mosquito olfactory function. EOs and their fractions capable of binding to such OBPs displayed repellence against female mosquitoes in a laboratory repellent assay. Repellent EOs were subjected to gas chromatographic analysis linked to antennogram (EAG) recordings from female A. gambiae to identify the biologically active constituents. Among these compounds cumin alcohol, carvacrol, ethyl cinnamate and butyl cinnamate proved as effective as DEET at an equivalent dose in the repellent assay, and combinations of carvacrol with either butyl cinnamate or cumin alcohol proved to be significantly more effective than DEET in the assay. When tested as spatial repellents in experimental shelters housing sleeping humans in northern Nigeria a binary mixture of carvacrol plus cumin alcohol caused mosquitoes to leave shelters in significantly higher numbers to those induced by DEET in female Anopheles spp. and in numbers equivalent to that of DEET in Culex spp. mosquitoes. These findings indicate an approach for the identification of biologically active molecules of natural origin serving as repellents for mosquitoes.
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Affiliation(s)
- Thomas Kröber
- Institute of Biology, Faculty of Science, University of Neuchâtel, rue Emile-Argand 11, 2000 Neuchâtel, Switzerland.
| | - Konstantinos Koussis
- Insect Molecular Genetics and Biotechnology Group, National Centre for Scientific Research "Demokritos", 153 10 Aghia Paraskevi, Athens, Greece.
| | - Martine Bourquin
- Institute of Biology, Faculty of Science, University of Neuchâtel, rue Emile-Argand 11, 2000 Neuchâtel, Switzerland.
| | - Panagiota Tsitoura
- Insect Molecular Genetics and Biotechnology Group, National Centre for Scientific Research "Demokritos", 153 10 Aghia Paraskevi, Athens, Greece.
| | - Maria Konstantopoulou
- Laboratory of Chemical Ecology and Natural Products, Institute of Biosciences & Applications, National Centre for Scientific Research "Demokritos", 153 10 Aghia Paraskevi, Athens, Greece.
| | | | | | - Huili Qiao
- Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy.
| | - Paolo Pelosi
- Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy.
| | - Kostas Iatrou
- Insect Molecular Genetics and Biotechnology Group, National Centre for Scientific Research "Demokritos", 153 10 Aghia Paraskevi, Athens, Greece.
| | - Patrick M Guerin
- Institute of Biology, Faculty of Science, University of Neuchâtel, rue Emile-Argand 11, 2000 Neuchâtel, Switzerland.
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9
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Messenger LA, Rowland M. Insecticide-treated durable wall lining (ITWL): future prospects for control of malaria and other vector-borne diseases. Malar J 2017; 16:213. [PMID: 28532494 PMCID: PMC5441104 DOI: 10.1186/s12936-017-1867-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 05/15/2017] [Indexed: 11/24/2022] Open
Abstract
While long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the cornerstones of malaria vector control throughout sub-Saharan Africa, there is an urgent need for the development of novel insecticide delivery mechanisms to sustain and consolidate gains in disease reduction and to transition towards malaria elimination and eradication. Insecticide-treated durable wall lining (ITWL) may represent a new paradigm for malaria control as a potential complementary or alternate longer-lasting intervention to IRS. ITWL can be attached to inner house walls, remain efficacious over multiple years and overcome some of the operational constraints of first-line control strategies, specifically nightly behavioural compliance required of LLINs and re-current costs and user fatigue associated with IRS campaigns. Initial experimental hut trials of insecticide-treated plastic sheeting reported promising results, achieving high levels of vector mortality, deterrence and blood-feeding inhibition, particularly when combined with LLINs. Two generations of commercial ITWL have been manufactured to date containing either pyrethroid or non-pyrethroid formulations. While some Phase III trials of these products have demonstrated reductions in malaria incidence, further large-scale evidence is still required before operational implementation of ITWL can be considered either in a programmatic or more targeted community context. Qualitative studies of ITWL have identified aesthetic value and observable entomological efficacy as key determinants of household acceptability. However, concerns have been raised regarding installation feasibility and anticipated cost-effectiveness. This paper critically reviews ITWL as both a putative mechanism of house improvement or more conventional intervention and discusses its future prospects as a method for controlling malaria and other vector-borne diseases.
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Affiliation(s)
- Louisa A Messenger
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
| | - Mark Rowland
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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10
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Killeen GF, Tatarsky A, Diabate A, Chaccour CJ, Marshall JM, Okumu FO, Brunner S, Newby G, Williams YA, Malone D, Tusting LS, Gosling RD. Developing an expanded vector control toolbox for malaria elimination. BMJ Glob Health 2017; 2:e000211. [PMID: 28589022 PMCID: PMC5444090 DOI: 10.1136/bmjgh-2016-000211] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 11/30/2016] [Accepted: 12/11/2016] [Indexed: 11/21/2022] Open
Abstract
Vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) accounts for most of the malaria burden reductions achieved recently in low and middle-income countries (LMICs). LLINs and IRS are highly effective, but are insufficient to eliminate malaria transmission in many settings because of operational constraints, growing resistance to available insecticides and mosquitoes that behaviourally avoid contact with these interventions. However, a number of substantive opportunities now exist for rapidly developing and implementing more diverse, effective and sustainable malaria vector control strategies for LMICs. For example, mosquito control in high-income countries is predominantly achieved with a combination of mosquito-proofed housing and environmental management, supplemented with large-scale insecticide applications to larval habitats and outdoor spaces that kill off vector populations en masse, but all these interventions remain underused in LMICs. Programmatic development and evaluation of decentralised, locally managed systems for delivering these proactive mosquito population abatement practices in LMICs could therefore enable broader scale-up. Furthermore, a diverse range of emerging or repurposed technologies are becoming available for targeting mosquitoes when they enter houses, feed outdoors, attack livestock, feed on sugar or aggregate into mating swarms. Global policy must now be realigned to mobilise the political and financial support necessary to exploit these opportunities over the decade ahead, so that national malaria control and elimination programmes can access a much broader, more effective set of vector control interventions.
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Affiliation(s)
- Gerry F Killeen
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, United Republic of Tanzania
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Allison Tatarsky
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, California, USA
| | - Abdoulaye Diabate
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Carlos J Chaccour
- Instituto de Salud Global, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
- Instituto de Salud Tropical, Universidad de Navarra, Pamplona, Spain
| | - John M Marshall
- Divisions of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, California, USA
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, United Republic of Tanzania
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Shannon Brunner
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, California, USA
| | - Gretchen Newby
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, California, USA
| | - Yasmin A Williams
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, California, USA
| | - David Malone
- Innovative Vector Control Consortium, Liverpool, UK
| | - Lucy S Tusting
- Oxford Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Roland D Gosling
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, California, USA
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11
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Kweka EJ, Lyaruu LJ, Mahande AM. Efficacy of PermaNet® 3.0 and PermaNet® 2.0 nets against laboratory-reared and wild Anopheles gambiae sensu lato populations in northern Tanzania. Infect Dis Poverty 2017; 6:11. [PMID: 28095897 PMCID: PMC5242039 DOI: 10.1186/s40249-016-0220-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 12/15/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mosquitoes have developed resistance against pyrethroids, the only class of insecticides approved for use on long-lasting insecticidal nets (LLINs). The present study sought to evaluate the efficacy of the pyrethroid synergist PermaNet® 3.0 LLIN versus the pyrethroid-only PermaNet® 2.0 LLIN, in an East African hut design in Lower Moshi, northern Tanzania. In this setting, resistance to pyrethroid insecticides has been identified in Anopheles gambiae mosquitoes. METHODS Standard World Health Organization bioefficacy evaluations were conducted in both laboratory and experimental huts. Experimental hut evaluations were conducted in an area where there was presence of a population of highly pyrethroid-resistant An. arabiensis mosquitoes. All nets used were subjected to cone bioassays and then to experimental hut trials. Mosquito mortality, blood-feeding inhibition and personal protection rate were compared between untreated nets, unwashed LLINs and LLINs that were washed 20 times. RESULTS Both washed and unwashed PermaNet® 2.0 and PermaNet® 3.0 LLINs had knockdown and mortality rates of 100% against a susceptible strain of An. gambiae sensu stricto. The adjusted mortality rate of the wild mosquito population after use of the unwashed PermaNet® 3.0 and PermaNet® 2.0 nets was found to be higher than after use of the washed PermaNet® 2.0 and PermaNet® 3.0 nets. CONCLUSIONS Given the increasing incidence of pyrethroid resistance in An. gambiae mosquitoes in Tanzania, we recommend that consideration is given to its distribution in areas with pyrethroid-resistant malaria vectors within the framework of a national insecticide-resistance management plan.
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Affiliation(s)
- Eliningaya J Kweka
- Tropical Pesticides Research Institute, Division of Livestock and Human Diseases Vector Control, Mosquito Section, P.O. Box 3024, Arusha, Tanzania. .,Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania.
| | - Lucile J Lyaruu
- Tropical Pesticides Research Institute, Division of Livestock and Human Diseases Vector Control, Mosquito Section, P.O. Box 3024, Arusha, Tanzania
| | - Aneth M Mahande
- Tropical Pesticides Research Institute, Division of Livestock and Human Diseases Vector Control, Mabogini field station, Moshi, Tanzania
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12
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Churcher TS, Lissenden N, Griffin JT, Worrall E, Ranson H. The impact of pyrethroid resistance on the efficacy and effectiveness of bednets for malaria control in Africa. eLife 2016; 5. [PMID: 27547988 PMCID: PMC5025277 DOI: 10.7554/elife.16090] [Citation(s) in RCA: 141] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/18/2016] [Indexed: 11/29/2022] Open
Abstract
Long lasting pyrethroid treated bednets are the most important tool for preventing malaria. Pyrethroid resistant Anopheline mosquitoes are now ubiquitous in Africa, though the public health impact remains unclear, impeding the deployment of more expensive nets. Meta-analyses of bioassay studies and experimental hut trials are used to characterise how pyrethroid resistance changes the efficacy of standard bednets, and those containing the synergist piperonyl butoxide (PBO), and assess its impact on malaria control. New bednets provide substantial personal protection until high levels of resistance, though protection may wane faster against more resistant mosquito populations as nets age. Transmission dynamics models indicate that even low levels of resistance would increase the incidence of malaria due to reduced mosquito mortality and lower overall community protection over the life-time of the net. Switching to PBO bednets could avert up to 0.5 clinical cases per person per year in some resistance scenarios. DOI:http://dx.doi.org/10.7554/eLife.16090.001 In recent years, widespread use of insecticide-treated bednets has prevented hundreds of thousands cases of malaria in Africa. Insecticide-treated bednets protect people in two ways: they provide a physical barrier that prevents the insects from biting and the insecticide kills mosquitos that come into contact with the net while trying to bite. Unfortunately, some mosquitoes in Africa are evolving so that they can survive contact with the insecticide currently used on bednets. How this emerging insecticide resistance is changing the number of malaria infections in Africa is not yet clear and it is difficult for scientists to study. To help mitigate the effects of insecticide resistance, scientists are testing new strategies to boost the effects of bednets, such as adding a second chemical that makes the insecticide on bednets more deadly to mosquitoes. In some places, adding this second chemical makes the nets more effective, but in others it does not. Moreover, these doubly treated, or “combination”, nets are more expensive and so it can be hard for health officials to decide whether and where to use them. Now, Churcher et al. have used computer modeling to help predict how insecticide resistance might change malaria infection rates and help determine when it makes sense to switch to the combination net. Insecticide-treated bednets provide good protection for individuals sleeping under them until relatively high levels of resistance are achieved, as measured using a simple test. As more resistant mosquitos survive encounters with the nets, the likelihood of being bitten before bed or while sleeping unprotected by a net increases. This is expected to increase malaria infections. As bednets age and are washed multiple times, they lose some of their insecticide and this problem becomes worse. Churcher et al. also show that the combination bednets may provide some additional protection against resistant mosquitos and reduce the number of malaria infections in some cases. The experiments show a simple test could help health officials determine which type of net would be most beneficial. The experiments and the model Churcher et al. created also may help scientists studying how to prevent increased spread of malaria in communities where mosquitos are becoming resistant to insecticide-treated nets. DOI:http://dx.doi.org/10.7554/eLife.16090.002
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Affiliation(s)
- Thomas S Churcher
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | | | - Jamie T Griffin
- MRC Centre for Outbreak Analysis and Modelling, Infectious Disease Epidemiology, Imperial College London, London, United Kingdom.,Queen Mary's University, London, United Kingdom
| | - Eve Worrall
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Hilary Ranson
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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13
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Msellemu D, Namango HI, Mwakalinga VM, Ntamatungiro AJ, Mlacha Y, Mtema ZJ, Kiware S, Lobo NF, Majambere S, Dongus S, Drakeley CJ, Govella NJ, Chaki PP, Killeen GF. The epidemiology of residual Plasmodium falciparum malaria transmission and infection burden in an African city with high coverage of multiple vector control measures. Malar J 2016; 15:288. [PMID: 27216734 PMCID: PMC4877954 DOI: 10.1186/s12936-016-1340-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Accepted: 05/11/2016] [Indexed: 12/11/2022] Open
Abstract
Background In the Tanzanian city of Dar es Salaam, high coverage of long-lasting insecticidal nets (LLINs), larvicide application (LA) and mosquito-proofed housing, was complemented with improved access to artemisinin-based combination therapy and rapid diagnostic tests by the end of 2012. Methods Three rounds of city-wide, cluster-sampled cross-sectional surveys of malaria parasite infection status, spanning 2010 to 2012, were complemented by two series of high-resolution, longitudinal surveys of vector density. Results Larvicide application using a granule formulation of Bacillus thuringiensis var. israelensis (Bti) had no effect upon either vector density (P = 0.820) or infection prevalence (P = 0.325) when managed by a private-sector contractor. Infection prevalence rebounded back to 13.8 % in 2010, compared with <2 % at the end of a previous Bti LA evaluation in 2008. Following transition to management by the Ministry of Health and Social Welfare (MoHSW), LA consistently reduced vector densities, first using the same Bti granule in early 2011 [odds ratio (OR) (95 % confidence interval (CI)) = 0.31 (0.14, 0.71), P = 0.0053] and then a pre-diluted aqueous suspension formulation from mid 2011 onwards [OR (95 % CI) = 0.15 (0.07, 0.30), P ≪ 0.000001]. While LA by MoHSW with the granule formulation was associated with reduced infection prevalence [OR (95 % CI) = 0.26 (0.12, 0.56), P = 0.00040], subsequent liquid suspension use, following a mass distribution to achieve universal coverage of LLINs that reduced vector density [OR (95 % CI) = 0.72 (0.51, 1.01), P = 0.057] and prevalence [OR (95 % CI) = 0.80 (0.69, 0.91), P = 0.0013], was not associated with further prevalence reduction (P = 0.836). Sleeping inside houses with complete window screens only reduced infection risk [OR (95 % CI) = 0.71 (0.62, 0.82), P = 0.0000036] if the evenings and mornings were also spent indoors. Furthermore, infection risk was only associated with local vector density [OR (95 % CI) = 6.99 (1.12, 43.7) at one vector mosquito per trap per night, P = 0.037] among the minority (14 %) of households lacking screening. Despite attenuation of malaria transmission and immunity, 88 % of infected residents experienced no recent fever, only 0.4 % of these afebrile cases had been treated for malaria, and prevalence remained high (9.9 %) at the end of the study. Conclusions While existing vector control interventions have dramatically attenuated malaria transmission in Dar es Salaam, further scale-up and additional measures to protect against mosquito bites outdoors are desirable. Accelerated elimination of chronic human infections persisting at high prevalence will require active, population-wide campaigns with curative drugs. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1340-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Daniel Msellemu
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Hagai I Namango
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,School of Biological Sciences, University of Nairobi, Nairobi, Kenya
| | - Victoria M Mwakalinga
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Alex J Ntamatungiro
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Yeromin Mlacha
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Zacharia J Mtema
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Samson Kiware
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Mathematics, Statistics and Computer Science, Marquette University, Milwaukee, WI, USA
| | - Neil F Lobo
- Eck Institute for Global Health, Notre Dame University, Notre Dame, IN, USA
| | - Silas Majambere
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Stefan Dongus
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.,Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Christopher J Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Nicodem J Govella
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Prosper P Chaki
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Gerry F Killeen
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania. .,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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14
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Mmbando AS, Okumu FO, Mgando JP, Sumaye RD, Matowo NS, Madumla E, Kaindoa E, Kiware SS, Lwetoijera DW. Effects of a new outdoor mosquito control device, the mosquito landing box, on densities and survival of the malaria vector, Anopheles arabiensis, inside controlled semi-field settings. Malar J 2015; 14:494. [PMID: 26645085 PMCID: PMC4673850 DOI: 10.1186/s12936-015-1013-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2015] [Accepted: 11/24/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The significance of malaria transmission occurring outdoors has risen even in areas where indoor interventions such as long-lasting insecticidal nets and indoor residual spraying are common. The actual contamination rates and effectiveness of recently developed outdoor mosquito control device, the mosquito landing box (MLB), on densities and daily survival of host-seeking laboratory Anopheles arabiensis, which readily bites humans outdoors was demonstrated. METHODS Experiments were conducted in large semi-field systems (SFS) with human volunteers inside, to mimic natural ecosystems, and using MLBs baited with natural or synthetic human odours and carbon dioxide. The MLBs were dusted with 10% pyriproxyfen (PPF) or entomopathogenic fungi (Metarhizium anisopliae) spores to mark mosquitoes physically contacting the devices. Each night, 400 laboratory-reared An. arabiensis females were released in one SFS chamber with two MLBs, and another chamber without MLBs (control). Mosquitoes were individually recaptured while attempting to bite volunteers inside SFS or by aspiration from SFS walls. Mosquitoes from chambers with PPF-treated MLBs and respective controls were individually dipped in water-filled cups containing ten conspecific third-instar larvae, whose subsequent development was monitored. Mosquitoes recaptured from chambers with fungi-treated MLBs were observed for fungal hyphal growth on their cadavers. Separately, effects on daily survival were determined by exposing An. arabiensis in chambers having MLBs treated with 5% pirimiphos methyl compared to chambers without MLBs (control), after which the mosquitoes were recaptured and monitored individually until they died. RESULTS Up to 63% (152/240) and 43% (92/210) of mosquitoes recaptured inside treatment chambers were contaminated with pyriproxyfen and M. anisopliae, respectively, compared to 8% (19/240) and 0% (0/164) in controls. The mean number of larvae emerging from cups in which adults from chambers with PPF-treated MLBs were dipped was significantly lower [0.75 (0.50-1.01)], than in controls [28.79 (28.32-29.26)], P < 0.001). Daily survival of mosquitoes exposed to 5% pirimiphos methyl was nearly two-fold lower than controls [hazard ratio (HR) = 1.748 (1.551-1.920), P < 0.001]. CONCLUSION High contamination rates in exposed mosquitoes even in presence of humans, demonstrates potential of MLBs for controlling outdoor-biting malaria vectors, either by reducing their survival or directly killing host-seeking mosquitoes. The MLBs also have potential for dispensing filial infanticides, such as PPF, which mosquitoes can transmit to their aquatic habitats for mosquito population control.
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Affiliation(s)
- Arnold S Mmbando
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
| | - Joseph P Mgando
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
| | - Robert D Sumaye
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
| | - Nancy S Matowo
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa.
| | - Edith Madumla
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
| | - Emmanuel Kaindoa
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
| | - Samson S Kiware
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- Department of Mathematics, Statistics and Computer Science, Marquette University, Milwaukee, WI, USA.
| | - Dickson W Lwetoijera
- Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania.
- Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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15
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Londono-Renteria B, Patel JC, Vaughn M, Funkhauser S, Ponnusamy L, Grippin C, Jameson SB, Apperson C, Mores CN, Wesson DM, Colpitts TM, Meshnick SR. Long-Lasting Permethrin-Impregnated Clothing Protects Against Mosquito Bites in Outdoor Workers. Am J Trop Med Hyg 2015. [PMID: 26195460 DOI: 10.4269/ajtmh.15-0130] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Outdoor exposure to mosquitoes is a risk factor for many diseases, including malaria and dengue. We have previously shown that long-lasting permethrin-impregnated clothing protects against tick and chigger bites in a double-blind randomized controlled trial in North Carolina outdoor workers. Here, we evaluated whether this clothing is protective against mosquito bites by measuring changes in antibody titers to mosquito salivary gland extracts. On average, there was a 10-fold increase in titer during the spring and summer when mosquito exposure was likely to be the highest. During the first year of the study, the increase in titer in subjects wearing treated uniforms was 2- to 2.5-fold lower than that of control subjects. This finding suggests that long-lasting permethrin-impregnated clothing provided protection against mosquito bites.
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Affiliation(s)
- Berlin Londono-Renteria
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Jaymin C Patel
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Meagan Vaughn
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Sheana Funkhauser
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Loganathan Ponnusamy
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Crystal Grippin
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Sam B Jameson
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Charles Apperson
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Christopher N Mores
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Dawn M Wesson
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Tonya M Colpitts
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
| | - Steven R Meshnick
- Department of Pathology, Immunology and Microbiology, University of South Carolina, Columbia, South Carolina; Department of Tropical Medicine, Tulane University, New Orleans, Louisiana; Department of Epidemiology, Gillings School of Global Public Health, Chapel Hill, North Carolina; Department of Entomology, North Carolina State University, Raleigh, North Carolina; Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana
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Kweka EJ, Munga S, Himeidan Y, Githeko AK, Yan G. Assessment of mosquito larval productivity among different land use types for targeted malaria vector control in the western Kenya highlands. Parasit Vectors 2015; 8:356. [PMID: 26142904 PMCID: PMC4491214 DOI: 10.1186/s13071-015-0968-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 06/27/2015] [Indexed: 11/10/2022] Open
Abstract
Background Mosquito larval source management (LSM) is likely to be more effective when adequate information such as dominant species, seasonal abundance, type of productive habitat, and land use type are available for targeted sites. LSM has been an effective strategy for reducing malaria morbidity in both urban and rural areas in Africa where sufficient proportions of larval habitats can be targeted. In this study, we conducted longitudinal larval source surveillance in the western Kenya highlands, generating data which can be used to establish cost-effective targeted intervention tools. Methods One hundred and twenty-four (124) positive larval habitats were monitored weekly and sampled for mosquito larvae over the 85-week period from 28 July 2009 to 3 March 2011. Two villages in the western Kenya highlands, Mbale and Iguhu, were included in the study. After preliminary sampling, habitats were classified into four types: hoof prints (n = 21; 17 % of total), swamps (n = 32; 26 %), abandoned goldmines (n = 35; 28 %) and drainage ditches (n = 36; 29 %). Positive habitats occurred in two land use types: farmland (66) and pasture (58). No positive larval habitats occurred in shrub land or forest. Results A total of 46,846 larvae were sampled, of which 44.1 % (20,907) were from abandoned goldmines, 30.9 % (14,469) from drainage ditches, 22.4 % (10,499) from swamps and 2.1 % (971) from hoof prints. In terms of land use types, 57.2 % (26,799) of the sampled larvae were from pasture and 42.8 % (20,047) were from farmland. Of the specimens identified morphologically, 24,583 (52.5 %) were Anopheles gambiae s.l., 11,901 (25.4 %) were Culex quinquefasciatus, 5628 (12 %) were An. funestus s.l. and 4734 (10.1 %) were other anopheline species (An. coustani, An. squamosus, An. ziemanni or An. implexus). Malaria vector dynamics varied seasonally, with An.gambiae s.s. dominating during wet season and An.arabiensis during dry season. An increased proportion of An. arabiensis was observed compared to previous studies. Conclusion These results suggest that long-term monitoring of larval habitats can establish effective surveillance systems and tools. Additionally, the results suggest that larval control is most effective in the dry season due to habitat restriction, with abandoned goldmines, drainage ditches and swamps being the best habitats to target. Both farmland and pasture should be targeted for effective larval control. An increased proportion of An. arabiensis in the An. gambiae complex was noticed in this study for the very first time in the western Kenya highlands; hence, further control tools should be in place for effective control of An. arabiensis.
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Affiliation(s)
- Eliningaya J Kweka
- Division of Livestock and Human Health Disease Vector Control, Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, Tanzania. .,Department of Medical Parasitology and Entomology, School of Medicine, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania. .,Pan African Mosquito Control Association (PAMCA), P.O. Box 9653, Dar es Salaam, Tanzania.
| | - Stephen Munga
- Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya.
| | - Yousif Himeidan
- Pan African Mosquito Control Association (PAMCA), P.O. Box 9653, Dar es Salaam, Tanzania. .,Entomology Unit, Faculty of Agriculture and Natural Resources, University of Kassala, P.O. Box 71, New Halfa, Sudan.
| | - Andrew K Githeko
- Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya.
| | - Guyuin Yan
- Program in Public Health, University of California, Irvine, CA, 92697, USA.
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Irish SR. The behaviour of mosquitoes in relation to humans under holed bednets: the evidence from experimental huts. Mem Inst Oswaldo Cruz 2014; 109:905-11. [PMID: 25410994 PMCID: PMC4296495 DOI: 10.1590/0074-0276140159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 08/15/2014] [Indexed: 11/22/2022] Open
Abstract
The physical integrity of bednets is a concern of national malaria control programs,
as it is a key factor in determining the rate of replacement of bednets. It is
largely assumed that increased numbers of holes will result in a loss of protection
of sleepers from potentially infective bites. Experimental hut studies are valuable
in understanding mosquito behaviour indoors, particularly as it relates to blood
feeding and mortality. This review summarises findings from experimental hut studies,
focusing on two issues: (i) the effect of different numbers or sizes of holes in
bednets and (ii) feeding behaviour and mortality with holed nets as compared with
unholed nets. As might be expected, increasing numbers and area of holes resulted in
increased blood feeding by mosquitoes on sleepers. However, the presence of holes did
not generally have a large effect on the mortality of mosquitoes. Successfully
entering a holed mosquito net does not necessarily mean that mosquitoes spend less
time in contact with the net, which could explain the lack in differences in
mortality. Further behavioural studies are necessary to understand mosquito behaviour
around nets and the importance of holed nets on malaria transmission.
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Affiliation(s)
- Seth R Irish
- Entomology Branch, Department of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Center for Global Health, Atlanta, GA, USA
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