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Takken W, Charlwood D, Lindsay SW. The behaviour of adult Anopheles gambiae, sub-Saharan Africa's principal malaria vector, and its relevance to malaria control: a review. Malar J 2024; 23:161. [PMID: 38783348 PMCID: PMC11112813 DOI: 10.1186/s12936-024-04982-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 05/11/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Mosquitoes of the Anopheles gambiae complex are one of the major vectors of malaria in sub-Saharan Africa. Their ability to transmit this disease of major public health importance is dependent on their abundance, biting behaviour, susceptibility and their ability to survive long enough to transmit malaria parasites. A deeper understanding of this behaviour can be exploited for improving vector surveillance and malaria control. FINDINGS Adult mosquitoes emerge from aquatic habitats at dusk. After a 24 h teneral period, in which the cuticle hardens and the adult matures, they may disperse at random and search upwind for a mate or to feed. Mating generally takes place at dusk in swarms that form over species-specific 'markers'. Well-nourished females may mate before blood-feeding, but the reverse is true for poorly-nourished insects. Females are monogamous and only mate once whilst males, that only feed on nectar, swarm nightly and can potentially mate up to four times. Females are able to locate hosts by following their carbon dioxide and odour gradients. When in close proximity to the host, visual cues, temperature and relative humidity are also used. Most blood-feeding occurs at night, indoors, with mosquitoes entering houses mainly through gaps between the roof and the walls. With the exception of the first feed, females are gonotrophically concordant and a blood meal gives rise to a complete egg batch. Egg development takes two or three days depending on temperature. Gravid females leave their resting sites at dusk. They are attracted by water gradients and volatile chemicals that provide a suitable aquatic habitat in which to lay their eggs. CONCLUSION Whilst traditional interventions, using insecticides, target mosquitoes indoors, additional protection can be achieved using spatial repellents outdoors, attractant traps or house modifications to prevent mosquito entry. Future research on the variability of species-specific behaviour, movement of mosquitoes across the landscape, the importance of light and vision, reproductive barriers to gene flow, male mosquito behaviour and evolutionary changes in mosquito behaviour could lead to an improvement in malaria surveillance and better methods of control reducing the current over-reliance on the indoor application of insecticides.
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Affiliation(s)
- Willem Takken
- Laboratory of Entomology, Wageningen University & Research, PO Box 16, 6700 AA, Wageningen, The Netherlands.
| | - Derek Charlwood
- Global Health and Tropical Medicine, Instituto de Hygiene e Medicina Tropical, Lisbon, Portugal
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Miarinjara A, Raveloson AO, Mugel SG, An N, Andriamiadanarivo A, Rajerison ME, Randremanana RV, Girod R, Gillespie TR. Socio-ecological risk factors associated with human flea infestations of rural household in plague-endemic areas of Madagascar. PLoS Negl Trop Dis 2024; 18:e0012036. [PMID: 38452122 PMCID: PMC10950221 DOI: 10.1371/journal.pntd.0012036] [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: 07/31/2023] [Revised: 03/19/2024] [Accepted: 02/29/2024] [Indexed: 03/09/2024] Open
Abstract
Plague is a flea-borne fatal disease caused by the bacterium Yersinia pestis, which persists in rural Madagascar. Although fleas parasitizing rats are considered the primary vectors of Y. pestis, the human flea, Pulex irritans, is abundant in human habitations in Madagascar, and has been found naturally infected by the plague bacterium during outbreaks. While P. irritans may therefore play a role in plague transmission if present in plague endemic areas, the factors associated with infestation and human exposure within such regions are little explored. To determine the socio-ecological risk factors associated with P. irritans infestation in rural households in plague-endemic areas of Madagascar, we used a mixed-methods approach, integrating results from P. irritans sampling, a household survey instrument, and an observational checklist. Using previously published vectorial capacity data, the minimal P. irritans index required for interhuman bubonic plague transmission was modeled to determine whether household infestations were enough to pose a plague transmission risk. Socio-ecological risk factors associated with a high P. irritans index were then identified for enrolled households using generalized linear models. Household flea abundance was also modeled using the same set of predictors. A high P. irritans index occurred in approximately one third of households and was primarily associated with having a traditional dirt floor covered with a plant fiber mat. Interventions targeting home improvement and livestock housing management may alleviate flea abundance and plague risk in rural villages experiencing high P. irritans infestation. As plague-control resources are limited in developing countries such as Madagascar, identifying the household parameters and human behaviors favoring flea abundance, such as those identified in this study, are key to developing preventive measures that can be implemented at the community level.
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Affiliation(s)
- Adélaïde Miarinjara
- Departments of Environmental Sciences and Environmental Health, Emory University and Rollins School of Public Health, Atlanta, United States of America
| | - Annick Onimalala Raveloson
- Medical Entomology Unit, Institut Pasteur de Madagascar, Antananarivo, Madagascar
- Ecole Doctorale Science de la Vie et de l’Environnement, Université d’Antananarivo, Antananarivo, Madagascar
| | - Stephen Gilbert Mugel
- Departments of Environmental Sciences and Environmental Health, Emory University and Rollins School of Public Health, Atlanta, United States of America
| | - Nick An
- Departments of Environmental Sciences and Environmental Health, Emory University and Rollins School of Public Health, Atlanta, United States of America
| | | | | | | | - Romain Girod
- Medical Entomology Unit, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - Thomas Robert Gillespie
- Departments of Environmental Sciences and Environmental Health, Emory University and Rollins School of Public Health, Atlanta, United States of America
- Centre Valbio, Ranomafana, Madagascar
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Lu C, Wang L, Jiang Y, Lan M, Wang F. Preconceptional, pregnant, and postnatal exposure to outdoor air pollution and indoor environmental factors: Effects on childhood parasitic infections. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169234. [PMID: 38101631 DOI: 10.1016/j.scitotenv.2023.169234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 11/26/2023] [Accepted: 12/07/2023] [Indexed: 12/17/2023]
Abstract
BACKGROUND Parasitic infections (PIs) are common and pose substantial health hazards in children globally, but the fundamental environmental variables exposure during crucial time window(s) are unclear. OBJECTIVES To identify key indoor and outdoor environmental factors leading to childhood PIs throughout critical time window(s). METHODS A combined cross-sectional and retrospective cohort study was performed on 8689 children residing in Changsha, China. Data was acquired pertaining to the health status and environmental exposure of the children in their homes. Personal exposure to outdoor air pollutants at the residential address during the preconceptional, perinatal, and postnatal periods was computed using data from ten air quality monitoring stations. An analysis of the relationships between childhood PIs and both indoor and outdoor factors was conducted using a multiple logistic regression model. RESULTS Childhood PIs were associated with outdoor CO and ozone (O3) exposure during the 10th-12th months prior to pregnancy, with ORs (95 % CI) of 1.68 (1.24-2.27) and 1.60 (1.15-2.22), respectively; childhood PIs were also associated with CO exposure during one year prior to pregnancy and the first trimester in utero [ORs = 1.57 (1.14-2.15) and 1.52 (1.17-1.97)]. Childhood PIs were found to be associated with PM2.5 exposure during pregnancy and the first year, with odds ratios of 1.51 (1.14-2.00) and 1.95 (1.22-3.12) per IQR increase in pollutant exposure, respectively. Exposures to smoke, renovation-related indoor air pollution (IAP), dampness and plant-related indoor allergens in the early life and past year were all associated with childhood PI, with odds ratios (95 % CI) ranging from 1.40 (1.01-1.95) for environmental tobacco smoke (ETS) during pregnancy to 1.63 (1.12-2.37) for mold/damp stains in the past year. In terms of PI risk, the early life and present periods were critical time windows for outdoor and indoor exposures, respectively. Certain individuals were more vulnerable to the PI risk associated with both indoor and outdoor exposures. Antibiotic use during child's lifetime and early years increased and decreased the PI risk of exposure to outdoor and indoor environments, respectively. CONCLUSIONS Exposure to outdoor air pollution in early life and indoor environments in the past year were found to be associated with childhood PI.
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Affiliation(s)
- Chan Lu
- XiangYa School of Public Health, Central South University, Changsha, China.
| | - Lin Wang
- XiangYa School of Public Health, Central South University, Changsha, China
| | - Ying Jiang
- XiangYa School of Public Health, Central South University, Changsha, China
| | - Mengju Lan
- XiangYa School of Public Health, Central South University, Changsha, China
| | - Faming Wang
- Division of Animal and Human Health Engineering, Department of Biosystems, KU Leuven, Leuven, Belgium
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Semakula HM, Liang S, Mukwaya PI, Mugagga F, Nseka D, Wasswa H, Mwendwa P, Kayima P, Achuu SP, Nakato J. Bayesian belief network modelling approach for predicting and ranking risk factors for malaria infections among children under 5 years in refugee settlements in Uganda. Malar J 2023; 22:297. [PMID: 37794401 PMCID: PMC10552276 DOI: 10.1186/s12936-023-04735-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 09/29/2023] [Indexed: 10/06/2023] Open
Abstract
BACKGROUND Malaria risk factors at household level are known to be complex, uncertain, stochastic, nonlinear, and multidimensional. The interplay among these factors, makes targeted interventions, and resource allocation for malaria control challenging. However, few studies have demonstrated malaria's transmission complexity, control, and integrated modelling, with no available evidence on Uganda's refugee settlements. Using the 2018-2019 Uganda's Malaria Indicator Survey (UMIS) data, an alternative Bayesian belief network (BBN) modelling approach was used to analyse, predict, rank and illustrate the conceptual reasoning, and complex causal relationships among the risk factors for malaria infections among children under-five in refugee settlements of Uganda. METHODS In the UMIS, household level information was obtained using standardized questionnaires, and a total of 675 children under 5 years were tested for malaria. From the dataset, a casefile containing malaria test results, demographic, social-economic and environmental information was created. The casefile was divided into a training (80%, n = 540) and testing (20%, n = 135) datasets. The training dataset was used to develop the BBN model following well established guidelines. The testing dataset was used to evaluate model performance. RESULTS Model accuracy was 91.11% with an area under the receiver-operating characteristic curve of 0.95. The model's spherical payoff was 0.91, with the logarithmic, and quadratic losses of 0.36, and 0.16 respectively, indicating a strong predictive, and classification ability of the model. The probability of refugee children testing positive, and negative for malaria was 48.1% and 51.9% respectively. The top ranked malaria risk factors based on the sensitivity analysis included: (1) age of child; (2) roof materials (i.e., thatch roofs); (3) wall materials (i.e., poles with mud and thatch walls); (4) whether children sleep under insecticide-treated nets; 5) type of toilet facility used (i.e., no toilet facility, and pit latrines with slabs); (6) walk time distance to water sources (between 0 and 10 min); (7) drinking water sources (i.e., open water sources, and piped water on premises). CONCLUSION Ranking, rather than the statistical significance of the malaria risk factors, is crucial as an approach to applied research, as it helps stakeholders determine how to allocate resources for targeted malaria interventions within the constraints of limited funding in the refugee settlements.
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Affiliation(s)
- Henry Musoke Semakula
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P.O Box 7062, Kampala, Uganda.
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, 2055 Mowry Rd, Gainesville, FL, 32610, USA.
- Department of Environmental Health Sciences, School of Public Health & Health Sciences, University of Massachusetts, Amherst, 01003, USA.
| | - Song Liang
- Department of Environmental Health Sciences, School of Public Health & Health Sciences, University of Massachusetts, Amherst, 01003, USA
| | - Paul Isolo Mukwaya
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P.O Box 7062, Kampala, Uganda
| | - Frank Mugagga
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P.O Box 7062, Kampala, Uganda
| | - Denis Nseka
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P.O Box 7062, Kampala, Uganda
| | - Hannington Wasswa
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P.O Box 7062, Kampala, Uganda
| | - Patrick Mwendwa
- Department of Horticulture and Food Security, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya
| | - Patrick Kayima
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P.O Box 7062, Kampala, Uganda
| | - Simon Peter Achuu
- National Environmental Management Authority (NEMA), Plot 17/19/21 Jinja Road, P.O. Box 22255, Kampala, Uganda
| | - Jovia Nakato
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P.O Box 7062, Kampala, Uganda
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Semakula HM, Liang S, Mukwaya PI, Mugagga F, Swahn M, Nseka D, Wasswa H, Kayima P. Determinants of malaria infections among children in refugee settlements in Uganda during 2018-2019. Infect Dis Poverty 2023; 12:31. [PMID: 37032366 PMCID: PMC10084630 DOI: 10.1186/s40249-023-01090-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 03/29/2023] [Indexed: 04/11/2023] Open
Abstract
BACKGROUND While 5% of 247 million global malaria cases are reported in Uganda, it is also a top refugee hosting country in Africa, with over 1.36 million refugees. Despite malaria being an emerging challenge for humanitarian response in refugee settlements, little is known about its risk factors. This study aimed to investigate the risk factors for malaria infections among children under 5 years of age in refugee settlements in Uganda. METHODS We utilized data from Uganda's Malaria Indicator Survey which was conducted between December 2018 and February 2019 at the peak of malaria season. In this national survey, household level information was obtained using standardized questionnaires and a total of 7787 children under 5 years of age were tested for malaria using mainly the rapid diagnostic test. We focused on 675 malaria tested children under five in refugee settlements located in Yumbe, Arua, Adjumani, Moyo, Lamwo, Kiryadongo, Kyegegwa, Kamwenge and Isingiro districts. The extracted variables included prevalence of malaria, demographic, social-economic and environmental information. Multivariable logistic regression was used to identify and define the malaria associated risk factors. RESULTS Overall, malaria prevalence in all refugee settlements across the nine hosting districts was 36.6%. Malaria infections were higher in refugee settlements located in Isingiro (98.7%), Kyegegwa (58.6%) and Arua (57.4%) districts. Several risk factors were significantly associated with acquisition of malaria including fetching water from open water sources [adjusted odds ratio (aOR) = 1.22, 95% CI: 0.08-0.59, P = 0.002], boreholes (aOR = 2.11, 95% CI: 0.91-4.89, P = 0.018) and water tanks (aOR = 4.47, 95% CI: 1.67-11.9, P = 0.002). Other factors included pit-latrines (aOR = 1.48, 95% CI: 1.03-2.13, P = 0.033), open defecation (aOR = 3.29, 95% CI: 1.54-7.05, P = 0.002), lack of insecticide treated bed nets (aOR = 1.15, 95% CI: 0.43-3.13, P = 0.003) and knowledge on the causes of malaria (aOR = 1.09, 95% CI: 0.79-1.51, P = 0.005). CONCLUSIONS The persistence of the malaria infections were mainly due to open water sources, poor hygiene, and lack of preventive measures that enhanced mosquito survival and infection. Malaria elimination in refugee settlements requires an integrated control approach that combines environmental management with other complementary measures like insecticide treated bed nets, indoor residual spraying and awareness.
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Affiliation(s)
- Henry Musoke Semakula
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda.
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, 2055 Mowry Rd, Gainesville, FL, 32610, USA.
| | - Song Liang
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, 2055 Mowry Rd, Gainesville, FL, 32610, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Paul Isolo Mukwaya
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
| | - Frank Mugagga
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
| | - Monica Swahn
- Wellstar College of Health and Human Services, Kennesaw State University, Kennesaw, NW, USA
| | - Denis Nseka
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
| | - Hannington Wasswa
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
| | - Patrick Kayima
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
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Khan A, Bisanzio D, Mutuku F, Ndenga B, Grossi-Soyster EN, Jembe Z, Maina PW, Chebii PK, Ronga CO, Okuta V, LaBeaud AD. Spatiotemporal overlapping of dengue, chikungunya, and malaria infections in children in Kenya. BMC Infect Dis 2023; 23:183. [PMID: 36991340 PMCID: PMC10053720 DOI: 10.1186/s12879-023-08157-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 03/14/2023] [Indexed: 03/31/2023] Open
Abstract
Malaria, chikungunya virus (CHIKV), and dengue virus (DENV) are endemic causes of fever among children in Kenya. The risks of infection are multifactorial and may be influenced by built and social environments. The high resolution overlapping of these diseases and factors affecting their spatial heterogeneity has not been investigated in Kenya. From 2014-2018, we prospectively followed a cohort of children from four communities in both coastal and western Kenya. Overall, 9.8% were CHIKV seropositive, 5.5% were DENV seropositive, and 39.1% were malaria positive (3521 children tested). The spatial analysis identified hot-spots for all three diseases in each site and in multiple years. The results of the model showed that the risk of exposure was linked to demographics with common factors for the three diseases including the presence of litter, crowded households, and higher wealth in these communities. These insights are of high importance to improve surveillance and targeted control of mosquito-borne diseases in Kenya.
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Affiliation(s)
- Aslam Khan
- Stanford University School of Medicine, Stanford, CA, USA.
- Center for Academic Medicine, 453 Quarry Road, Palo Alto, CA, 94304, USA.
| | | | | | | | | | - Zainab Jembe
- Msambweni County Referral hospital, Msambweni, Kenya
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Abong’o B, Gimnig JE, Omoke D, Ochomo E, Walker ED. Screening eaves of houses reduces indoor mosquito density in rural, western Kenya. Malar J 2022; 21:377. [PMID: 36494664 PMCID: PMC9733111 DOI: 10.1186/s12936-022-04397-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 11/22/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Despite the scale-up of insecticide-treated nets and indoor residual spraying, the bulk of malaria transmission in western Kenya still occurs indoors, late at night. House improvement is a potential long-term solution to further reduce malaria transmission in the region. METHODS The impact of eave screening on mosquito densities was evaluated in two rural villages in western Kenya. One-hundred-and-twenty pairs of structurally similar, neighbouring houses were used in the study. In each pair, one house was randomly selected to receive eave screening at the beginning of the study while the other remained unscreened until the end of the sampling period. Mosquito sampling was performed monthly by motorized aspiration method for 4 months. The collected mosquitoes were analysed for species identification. RESULTS Compared to unscreened houses, significantly fewer female Anopheles funestus (RR = 0.40, 95% CI 0.29-0.55), Anopheles gambiae Complex (RR = 0.46, 95% CI 0.34-0.62) and Culex species (RR = 0.53, 95% CI 0.45-0.61) were collected in screened houses. No significant differences in the densities of the mosquitoes were detected in outdoor collections. Significantly fewer Anopheles funestus were collected indoors from houses with painted walls (RR = 0.05, 95% CI 0.01-0.38) while cooking in the house was associated with significantly lower numbers of Anopheles gambiae Complex indoors (RR = 0.60, 95% CI 0.45-0.79). Nearly all house owners (99.6%) wanted their houses permanently screened, including 97.7% that indicated a willingness to use their own resources. However, 99.2% required training on house screening. The cost of screening a single house was estimated at KES6,162.38 (US$61.62). CONCLUSION Simple house modification by eave screening has the potential to reduce the indoor occurrence of both Anopheles and Culex mosquito species. Community acceptance was very high although education and mobilization may be needed for community uptake of house modification for vector control. Intersectoral collaboration and favourable government policies on housing are important links towards the adoption of house improvements for malaria control.
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Affiliation(s)
- Bernard Abong’o
- grid.33058.3d0000 0001 0155 5938Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578-40100, Kisumu, Kenya
| | - John E. Gimnig
- grid.416738.f0000 0001 2163 0069Centers for Disease Control and Prevention, Division of Parasitic Diseases, Atlanta, GA 30341 USA
| | - Diana Omoke
- grid.33058.3d0000 0001 0155 5938Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578-40100, Kisumu, Kenya
| | - Eric Ochomo
- grid.33058.3d0000 0001 0155 5938Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578-40100, Kisumu, Kenya
| | - Edward D. Walker
- grid.17088.360000 0001 2150 1785Michigan State University, 6169 Biomedical Physical Sciences Building, East Lansing, MI 48824 USA
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Abstract
BACKGROUND Malaria remains an important public health problem. Research in 1900 suggested house modifications may reduce malaria transmission. A previous version of this review concluded that house screening may be effective in reducing malaria. This update includes data from five new studies. OBJECTIVES To assess the effects of house modifications that aim to reduce exposure to mosquitoes on malaria disease and transmission. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (PubMed); Embase (OVID); Centre for Agriculture and Bioscience International (CAB) Abstracts (Web of Science); and the Latin American and Caribbean Health Science Information database (LILACS) up to 25 May 2022. We also searched the World Health Organization International Clinical Trials Registry Platform, ClinicalTrials.gov, and the ISRCTN registry to identify ongoing trials up to 25 May 2022. SELECTION CRITERIA Randomized controlled trials, including cluster-randomized controlled trials (cRCTs), cross-over studies, and stepped-wedge designs were eligible, as were quasi-experimental trials, including controlled before-and-after studies, controlled interrupted time series, and non-randomized cross-over studies. We sought studies investigating primary construction and house modifications to existing homes reporting epidemiological outcomes (malaria case incidence, malaria infection incidence or parasite prevalence). We extracted any entomological outcomes that were also reported in these studies. DATA COLLECTION AND ANALYSIS Two review authors independently selected eligible studies, extracted data, and assessed the risk of bias. We used risk ratios (RR) to compare the effect of the intervention with the control for dichotomous data. For continuous data, we presented the mean difference; and for count and rate data, we used rate ratios. We presented all results with 95% confidence intervals (CIs). We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS One RCT and six cRCTs met our inclusion criteria, with an additional six ongoing RCTs. We did not identify any eligible non-randomized studies. All included trials were conducted in sub-Saharan Africa since 2009; two randomized by household and four at the block or village level. All trials assessed screening of windows, doors, eaves, ceilings, or any combination of these; this was either alone, or in combination with roof modification or eave tube installation (an insecticidal "lure and kill" device that reduces mosquito entry whilst maintaining some airflow). In one trial, the screening material was treated with 2% permethrin insecticide. In five trials, the researchers implemented the interventions. A community-based approach was adopted in the other trial. Overall, the implementation of house modifications probably reduced malaria parasite prevalence (RR 0.68, 95% CI 0.57 to 0.82; 5 trials, 5183 participants; moderate-certainty evidence), although an inconsistent effect was observed in a subpopulation of children in one study. House modifications reduced moderate to severe anaemia prevalence (RR 0.70, 95% CI 0.55 to 0.89; 3 trials, 3643 participants; high-certainty evidence). There was no consistent effect on clinical malaria incidence, with rate ratios ranging from 0.38 to 1.62 (3 trials, 3365 participants, 4126.6 person-years). House modifications may reduce indoor mosquito density (rate ratio 0.63, 95% CI 0.30 to 1.30; 4 trials, 9894 household-nights; low-certainty evidence), although two studies showed little effect on this parameter. AUTHORS' CONCLUSIONS House modifications - largely screening, sometimes combined with insecticide and lure and kill devices - were associated with a reduction in malaria parasite prevalence and a reduction in people with anaemia. Findings on malaria incidence were mixed. Modifications were also associated with lower indoor adult mosquito density, but this effect was not present in some studies.
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Affiliation(s)
- Tilly Fox
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Marty Chaplin
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Mark Napier
- Council for Scientific and Industrial Research, Pretoria, South Africa
- Centre for Development Support, University of the Free State, Bloemfontein, South Africa
| | - Evelyn A Olanga
- Malaria Alert Centre of the College of Medicine, Blantyre, Malawi
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Asale A, Kassie M, Abro Z, Enchalew B, Belay A, Sangoro PO, Tchouassi DP, Mutero CM. The combined impact of LLINs, house screening, and pull-push technology for improved malaria control and livelihoods in rural Ethiopia: study protocol for household randomised controlled trial. BMC Public Health 2022; 22:930. [PMID: 35538444 PMCID: PMC9088127 DOI: 10.1186/s12889-022-12919-1] [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: 07/30/2021] [Accepted: 03/04/2022] [Indexed: 11/23/2022] Open
Abstract
Background The combined application of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are commonly used malaria interventions that target indoor Anopheles vectors. Recent studies on the effects of house screening (HS) and LLINs have demonstrated a reduction in indoor vector densities and malaria when the interventions are combined. In addition, complementary interventions are needed to curb co-occurring pest populations which pose menace to agricultural crop productivity and food security. However, interventions that impact malaria mainly centre on public health strategies, overlooking subtle but important component of agricultural measures. Addressing the coexisting risks of malaria and crop pests could contribute to improved livelihood of communities. Methods A four-armed household, cluster-randomized, controlled study will be conducted to assess the combined impact of HS, LLINs and push-pull agricultural technology (PPT) against clinical malaria in children in Ethiopia. The unit of randomization will be the household, which includes a house and its occupants. A total of 838 households will be enrolled in this study. In this trial 246 households will receive LLINs and HS, 250 will receive LLINs, HS and PPT, 175 households will receive LLINs and PPT. The remaining 167 houses which receive LLINs only will be used as control. One child aged ≤14 years will be enrolled per household in each treatment and followed for clinical malaria using active case detection to estimate malaria incidence for two malaria transmission seasons. Discussion Episodes of clinical malaria, density of indoor biting malaria vectors, sporozoite infection rate, improved crop infestation rate, crop yield gain, livestock productivity and cost effectiveness analysis will be the end points of this study. Socio-economic, social demographic, cost-effectiveness analysis will be conducted using qualitative and participatory methods to explore the acceptability of HS and PPT. Documenting the combined impact of LLINs, HS and PPT on the prevalence of clinical malaria and crop pest damage will be the first of its kind. Trial registration Pan African Clinical Trials Registry, PACTR202006878245287. 24/06/2020. https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=11101. Supplementary Information The online version contains supplementary material available at 10.1186/s12889-022-12919-1.
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Affiliation(s)
- Abebe Asale
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia.
| | - Menale Kassie
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Zewdu Abro
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Bayu Enchalew
- International Centre of Insect Physiology and Ecology, Addis Ababa, Ethiopia
| | - Aklilu Belay
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
| | - Peter O Sangoro
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - David P Tchouassi
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Clifford M Mutero
- International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,University of Pretoria Institute for Sustainable Malaria Control, School of Health Systems and Public Health, University of Pretoria, Pretoria, South Africa
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10
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Musiime AK, Krezanoski PJ, Smith DL, Kilama M, Conrad MD, Otto G, Kyagamba P, Asiimwe J, Rek J, Nankabirwa JI, Arinaitwe E, Akol AM, Kamya MR, Staedke SG, Drakeley C, Bousema T, Lindsay SW, Dorsey G, Tusting LS. House design and risk of malaria, acute respiratory infection and gastrointestinal illness in Uganda: A cohort study. PLOS GLOBAL PUBLIC HEALTH 2022; 2:e0000063. [PMID: 36962263 PMCID: PMC10022195 DOI: 10.1371/journal.pgph.0000063] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 11/15/2021] [Indexed: 11/18/2022]
Abstract
House construction is rapidly modernizing across Africa but the potential benefits for human health are poorly understood. We hypothesised that improvements to housing would be associated with reductions in malaria, acute respiratory infection (ARI) and gastrointestinal illness in an area of low malaria endemicity in Uganda. Data were analysed from a cohort study of male and female child and adult residents (n = 531) of 80 randomly-selected households in Nagongera sub-county, followed for 24 months (October 4, 2017 to October 31, 2019). Houses were classified as modern (brick walls, metal roof and closed eaves) or traditional (all other homes). Light trap collections of mosquitoes were done every two weeks in all sleeping rooms. Every four weeks, we measured malaria infection (using microscopy and qPCR to detect malaria parasites), incidence of malaria, ARI and gastrointestinal illness. We collected 15,780 adult female Anopheles over 7,631 nights. We collected 13,277 blood samples of which 10.2% (1,347) were positive for malaria parasites. Over 958 person years we diagnosed 38 episodes of uncomplicated malaria (incidence 0.04 episodes per person-year at risk), 2,553 episodes of ARI (incidence 2.7 episodes per person-year) and 387 episodes of gastrointestinal illness (incidence 0.4 episodes per person-year). Modern houses were associated with a 53% lower human biting rate compared to traditional houses (adjusted incidence rate ratio [aIRR] 0.47, 95% confidence interval [CI] 0.32-0.67, p<0.001) and a 24% lower incidence of gastrointestinal illness (aIRR 0.76, 95% CI 0.59-0.98, p = 0.04) but no changes in malaria prevalence, malaria incidence nor ARI incidence. House improvements may reduce mosquito-biting rates and gastrointestinal illness among children and adults. For the health sector to leverage Africa's housing modernization, research is urgently needed to identify the healthiest house designs and to assess their effectiveness across a range of epidemiological settings in sub-Saharan Africa.
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Affiliation(s)
- Alex K Musiime
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Paul J Krezanoski
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, United States of America
| | - David L Smith
- Department of Health Metrics Sciences, University of Washington, Seattle, United States of America
| | - Maxwell Kilama
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Melissa D Conrad
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, United States of America
| | - Geoffrey Otto
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | | | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | | | - Anne M Akol
- Department of Zoology, Entomology and Fisheries Sciences, College of Natural Sciences, Makerere University, Kampala, Uganda
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Sarah G Staedke
- Faculty of Infectious and Tropical Diseases, Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Steve W Lindsay
- Department of Biosciences, Durham University, Durham, United Kingdom
| | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, United States of America
| | - Lucy S Tusting
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Centre on Climate Change and Planetary Health, London School of Hygiene & Tropical Medicine, London, United Kingdom
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11
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Kawada H, Nakazawa S, Ohashi K, Kambewa EA, Pemba DF. Indoor environmental factors and house structures affect vaporization of active ingredient from spatial repellent devices placed in typical rural houses in south eastern Malawi. Jpn J Infect Dis 2021; 75:288-295. [PMID: 34853193 DOI: 10.7883/yoken.jjid.2021.584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The use of a metofluthrin-impregnated spatial repellent device (MSRD) is a new, practically effective method for preventing mosquito blood feeding. Indoor environmental factors such as room temperature and ventilation rate are thought to be important for MSRD activity. Measurements of room temperature and vaporization of metofluthrin from MSRD in typical rural metal-roof houses and thatched-roof houses in southeastern Malawi were conducted. The relationship between house structure and number of collected Anopheline mosquitoes with and without MSRD treatment was also investigated. The difference between daytime room temperature and nighttime room temperature was significantly higher in metal-roof houses than thatched-roof houses. The vaporization of metofluthrin from the MSRD was not accelerated by the high room temperature, but by the high indoor air flow by ventilation. The number of mosquito collections was significantly higher in thatched-roof houses than in metal-roof houses. MSRD-treated thatched-roof houses have a higher probability of mosquito infestation, but the vaporization of metofluthrin is also higher due to indoor air flow, resulting in a reduction in mosquito numbers. Metal-roof houses with closed eaves reduce the probability of mosquito invasion, and a longer predicted effectiveness occurs with MSRD because of the controlled release of metofluthrin through lower indoor air flow.
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Affiliation(s)
- Hitoshi Kawada
- Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, JAPAN
| | - Shusuke Nakazawa
- Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, JAPAN
| | - Kazunori Ohashi
- Health and Crop Sciences Research Laboratory, Sumitomo Chemical Co., Ltd., JAPAN
| | - Eggrey Aisha Kambewa
- Vector Borne Disease Laboratory, Chancellor College, University of Malawi, Republic of Malawi
| | - Dylo Foster Pemba
- Vector Borne Disease Laboratory, Chancellor College, University of Malawi, Republic of Malawi
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12
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Carrasco-Tenezaca M, Jatta E, Jawara M, Bradley J, Pinder M, D'Alessandro U, Knudsen J, Lindsay SW. Effect of roof colour on indoor temperature and human comfort levels, with implications for malaria control: a pilot study using experimental houses in rural Gambia. Malar J 2021; 20:423. [PMID: 34715869 PMCID: PMC8555212 DOI: 10.1186/s12936-021-03951-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
Background In rural sub-Saharan Africa, thatch roofs are being replaced by metal roofs. Metal roofing, however, increases indoor temperatures above human comfort levels, and thus makes it more likely that residents will not use an insecticide-treated bed net (ITN) at night. Whether the colour of a metal roof affects indoor temperature and human comfort was assessed. Methods Two identical, experimental houses were constructed with metal roofs in rural Gambia. Roof types were: (1) original bare-metal, (2) painted with red oxide primer or (3) white gloss, to reflect solar radiation. Pairwise comparisons were run in six, five-night blocks during the malaria season 2018. Indoor climate was measured in each house and multivariate analysis used to compare indoor temperatures during the day and night. Results From 21.00 to 23.59 h, when most residents decide whether to use an ITN or not, the indoor temperature of a house with a bare metal roof was 31.5 °C (95% CI 31.2–31.8 °C), a red roof, 30.3 °C (95% CI 30.0–30.6) and a white roof, 29.8 °C (95% CI 29.4–30.1). During the same period, red-roofed houses were 1.23 °C cooler (95% CI 1.22–1.23) and white roofs 1.74 °C cooler (95% CI 1.70–1.79) than bare-metal roofed houses (p < 0.001). Similar results were found from 00.00 to 06.00 h. Maximum daily temperatures were 0.93 °C lower in a white-roofed house (95% CI 0.10–0.30, p < 0.001), but not a red roof (mean maximum temperature difference = 0.44 °C warmer, 95% CI 0.43–0.45, p = 0.081), compared with the bare-metal roofed houses. Human comfort analysis showed that from 21.00 to 23.59 h houses with white roofs (comfortable for 87% time) were more comfortable than bare-metal roofed houses (comfortable for 13% time; odds ratio = 43.7, 95% CI 27.5–69.5, p < 0.001). The cost of painting a metal roof white is approximately 31–68 USD. Conclusions Houses with a white roof were consistently cooler and more comfortable than those with a bare metal roof. Painting the roofs of houses white is a cheap way of making a dwelling more comfortable for the occupants and could potentially increase bed net use in hot humid countries. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03951-4.
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Affiliation(s)
| | - Ebrima Jatta
- National Malaria Control Programme, Banjul, The Gambia
| | - Musa Jawara
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - John Bradley
- London School of Hygiene & Tropical Medicine, MRC International Statistics and Epidemiology Group, London, UK
| | - Margaret Pinder
- Department of Biosciences, Durham University, Durham, UK.,Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia.,Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Jakob Knudsen
- Schools of Architecture, Design and Conservation, The Royal Danish Academy of Fine Arts, Copenhagen, Denmark
| | - Steve W Lindsay
- Department of Biosciences, Durham University, Durham, UK. .,Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
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13
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Yaro JB, Tiono AB, Sanou A, Toe HK, Bradley J, Ouedraogo A, Ouedraogo ZA, Guelbeogo MW, Agboraw E, Worrall E, Sagnon N'F, Lindsay SW, Wilson AL. Risk factors associated with house entry of malaria vectors in an area of Burkina Faso with high, persistent malaria transmission and high insecticide resistance. Malar J 2021; 20:397. [PMID: 34629053 PMCID: PMC8504047 DOI: 10.1186/s12936-021-03926-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 09/26/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In rural Burkina Faso, the primary malaria vector Anopheles gambiae sensu lato (s.l.) primarily feeds indoors at night. Identification of factors which influence mosquito house entry could lead to development of novel malaria vector control interventions. A study was therefore carried out to identify risk factors associated with house entry of An. gambiae s.l. in south-west Burkina Faso, an area of high insecticide resistance. METHODS Mosquitoes were sampled monthly during the malaria transmission season using CDC light traps in 252 houses from 10 villages, each house sleeping at least one child aged five to 15 years old. Potential risk factors for house entry of An. gambiae s.l. were measured, including socio-economic status, caregiver's education and occupation, number of people sleeping in the same part of the house as the child, use of anti-mosquito measures, house construction and fittings, proximity of anopheline aquatic habitats and presence of animals near the house. Mosquito counts were compared using a generalized linear mixed-effect model with negative binomial and log link function, adjusting for repeated collections. RESULTS 20,929 mosquitoes were caught, of which 16,270 (77.7%) were An. gambiae s.l. Of the 6691 An. gambiae s.l. identified to species, 4101 (61.3%) were An. gambiae sensu stricto and 2590 (38.7%) Anopheles coluzzii. Having a metal-roof on the child's sleeping space (IRR = 0.55, 95% CI 0.32-0.95, p = 0.03) was associated with fewer malaria vectors inside the home. CONCLUSION This study demonstrated that the rate of An. gambiae s.l. was 45% lower in sleeping spaces with a metal roof, compared to those with thatch roofs. Improvements in house construction, including installation of metal roofs, should be considered in endemic areas of Africa to reduce the burden of malaria.
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Affiliation(s)
- Jean Baptiste Yaro
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso.,Department of Biosciences, Durham University, Durham, UK
| | - Alfred B Tiono
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - Antoine Sanou
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - Hyacinthe K Toe
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Alphonse Ouedraogo
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - Z Amidou Ouedraogo
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - Moussa W Guelbeogo
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | - Efundem Agboraw
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Eve Worrall
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - N 'Fale Sagnon
- Centre National de Recherche Et de Formation Sur Le Paludisme, Ouagadougou, Burkina Faso
| | | | - Anne L Wilson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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14
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Characterizing Small-Town Development Using Very High Resolution Imagery within Remote Rural Settings of Mozambique. REMOTE SENSING 2021. [DOI: 10.3390/rs13173385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
While remotely sensed images of various resolutions have been widely used in identifying changes in urban and peri-urban environments, only very high resolution (VHR) imagery is capable of providing the information needed for understanding the changes taking place in remote rural environments, due to the small footprints and low density of man-made structures in these settings. However, limited by data availability, mapping man-made structures and conducting subsequent change detections in remote areas are typically challenging and thus require a certain level of flexibility in algorithm design that takes into account the specific environmental and image conditions. In this study, we mapped all buildings and corrals for two remote villages in Mozambique based on two single-date VHR images that were taken in 2004 and 2012, respectively. Our algorithm takes advantage of the presence of shadows and, through a fusion of both spectra- and object-based analysis techniques, is able to differentiate buildings with metal and thatch roofs with high accuracy (overall accuracy of 86% and 94% for 2004 and 2012, respectively). The comparison of the mapping results between 2004 and 2012 reveals multiple lines of evidence suggesting that both villages, while differing in many aspects, have experienced substantial increases in the economic status. As a case study, our project demonstrates the capability of a coupling of VHR imagery with locally adjusted classification algorithms to infer the economic development of small, remote rural settlements.
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15
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Hamid-Adiamoh M, Nwakanma D, Assogba BS, Ndiath MO, D’Alessandro U, Afrane YA, Amambua-Ngwa A. Influence of insecticide resistance on the biting and resting preferences of malaria vectors in the Gambia. PLoS One 2021; 16:e0241023. [PMID: 34166376 PMCID: PMC8224845 DOI: 10.1371/journal.pone.0241023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 06/11/2021] [Indexed: 11/23/2022] Open
Abstract
Background The scale-up of indoor residual spraying and long-lasting insecticidal nets, together with other interventions have considerably reduced the malaria burden in The Gambia. This study examined the biting and resting preferences of the local insecticide-resistant vector populations few years following scale-up of anti-vector interventions. Method Indoor and outdoor-resting Anopheles gambiae mosquitoes were collected between July and October 2019 from ten villages in five regions in The Gambia using pyrethrum spray collection (indoor) and prokopack aspirator from pit traps (outdoor). Polymerase chain reaction assays were performed to identify molecular species, insecticide resistance mutations, Plasmodium infection rate and host blood meal. Results A total of 844 mosquitoes were collected both indoors (421, 49.9%) and outdoors (423, 50.1%). Four main vector species were identified, including An. arabiensis (indoor: 15%, outdoor: 26%); An. coluzzii (indoor: 19%, outdoor: 6%), An. gambiae s.s. (indoor: 11%, outdoor: 16%), An. melas (indoor: 2%, outdoor: 0.1%) and hybrids of An. coluzzii-An. gambiae s.s (indoors: 3%, outdoors: 2%). A significant preference for outdoor resting was observed in An. arabiensis (Pearson X2 = 22.7, df = 4, P<0.001) and for indoor resting in An. coluzzii (Pearson X2 = 55.0, df = 4, P<0.001). Prevalence of the voltage-gated sodium channel (Vgsc)-1014S was significantly higher in the indoor-resting (allele freq. = 0.96, 95%CI: 0.78–1, P = 0.03) than outdoor-resting (allele freq. = 0.82, 95%CI: 0.76–0.87) An. arabiensis population. For An. coluzzii, the prevalence of most mutation markers was higher in the outdoor (allele freq. = 0.92, 95%CI: 0.81–0.98) than indoor-resting (allele freq. = 0.78, 95%CI: 0.56–0.86) mosquitoes. However, in An. gambiae s.s., the prevalence of Vgsc-1014F, Vgsc-1575Y and GSTe2-114T was high (allele freq. = 0.96–1), but did not vary by resting location. The overall sporozoite positivity rate was 1.3% (95% CI: 0.5–2%) in mosquito populations. Indoor-resting An. coluzzii had mainly fed on human blood while indoor-resting An. arabiensis fed on animal blood. Conclusion In this study, high levels of resistance mutations were observed that could be influencing the mosquito populations to rest indoors or outdoors. The prevalent animal-biting behaviour demonstrated in the mosquito populations suggest that larval source management could be an intervention to complement vector control in this setting.
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Affiliation(s)
- Majidah Hamid-Adiamoh
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Accra, Ghana
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
- * E-mail:
| | - Davis Nwakanma
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Benoit Sessinou Assogba
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Mamadou Ousmane Ndiath
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Umberto D’Alessandro
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Yaw A. Afrane
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular, University of Ghana, Legon, Accra, Ghana
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Accra, Ghana
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit, The Gambia at The London School of Hygiene & Tropical Medicine, Banjul, The Gambia
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16
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Deutsch-Feldman M, Brazeau NF, Parr JB, Thwai KL, Muwonga J, Kashamuka M, Tshefu Kitoto A, Aydemir O, Bailey JA, Edwards JK, Verity R, Emch M, Gower EW, Juliano JJ, Meshnick SR. Spatial and epidemiological drivers of Plasmodium falciparum malaria among adults in the Democratic Republic of the Congo. BMJ Glob Health 2021; 5:bmjgh-2020-002316. [PMID: 32601091 PMCID: PMC7326263 DOI: 10.1136/bmjgh-2020-002316] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 04/22/2020] [Accepted: 04/25/2020] [Indexed: 11/17/2022] Open
Abstract
Background Adults are frequently infected with malaria and may serve as a reservoir for further transmission, yet we know relatively little about risk factors for adult infections. In this study, we assessed malaria risk factors among adults using samples from the nationally representative, cross-sectional 2013–2014 Demographic and Health Survey (DHS) conducted in the Democratic Republic of the Congo (DRC). We further explored differences in risk factors by urbanicity. Methods Plasmodium falciparum infection was determined by PCR. Covariates were drawn from the DHS to model individual, community and environmental-level risk factors for infection. Additionally, we used deep sequencing data to estimate the community-level proportions of drug-resistant infections and included these estimates as potential risk factors. All identified factors were assessed for differences in associations by urbanicity. Results A total of 16 126 adults were included. Overall prevalence of malaria was 30.3% (SE=1.1) by PCR; province-level prevalence ranged from 6.7% to 58.3%. Only 17% of individuals lived in households with at least one bed-net for every two people, as recommended by the WHO. Protective factors included increasing within-household bed-net coverage (Prevalence Ratio=0.85, 95% CI=0.76–0.95) and modern housing (PR=0.58, 95% CI=0.49–0.69). Community-level protective factors included increased median wealth (PR=0.87, 95% CI=0.83–0.92). Education, wealth, and modern housing showed protective associations in cities but not in rural areas. Conclusions The DRC continues to suffer from a high burden of malaria; interventions that target high-risk groups and sustained investment in malaria control are sorely needed. Areas of high prevalence should be prioritised for interventions to target the largest reservoirs for further transmission.
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Affiliation(s)
- Molly Deutsch-Feldman
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Nicholas F Brazeau
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jonathan B Parr
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Kyaw L Thwai
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jeremie Muwonga
- National AIDS Control Program, Kinshasa, Congo (the Democratic Republic)
| | - Melchior Kashamuka
- School of Public Health, University of Kinshasa Faculty of Medicine, Kinshasa, Congo (the Democratic Republic)
| | - Antoinette Tshefu Kitoto
- School of Public Health, University of Kinshasa Faculty of Medicine, Kinshasa, Congo (the Democratic Republic)
| | - Ozkan Aydemir
- Department of Pathology and Laboratory Medicine, Brown University Warren Alpert Medical School, Providence, Rhode Island, USA
| | - Jeffrey A Bailey
- Department of Pathology and Laboratory Medicine, Brown University Warren Alpert Medical School, Providence, Rhode Island, USA
| | - Jessie K Edwards
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Robert Verity
- Medical Research Council Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Michael Emch
- Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Emily W Gower
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jonathan J Juliano
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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17
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Sikalima J, Schue JL, Hill SE, Mulenga M, Handema R, Daka V, Chileshe J, Kasongo W, Chaponda M, Bukasa Kabuya JB, Moss WJ, Ippolito MM. House Structure Is Associated with Malaria among Febrile Patients in a High-Transmission Region of Zambia. Am J Trop Med Hyg 2021; 104:2131-2138. [PMID: 33844650 DOI: 10.4269/ajtmh.20-1378] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/10/2021] [Indexed: 11/07/2022] Open
Abstract
Since the late nineteenth century, the importance of house structure as a determinant of malaria risk has been recognized. Few studies to date have examined the association of housing and malaria in clinical populations. We conducted a cross-sectional study of febrile patients (n = 282) at two rural health clinics in a high malaria-transmission area of northern Zambia. Participants underwent testing for Plasmodium falciparum infection by PCR. Demographic and other risk factors including house structure, indoor residual spraying (IRS), bed net use, education level, and household income were collected. Data were fitted to logistic regression models for relational and mediation analyses. Residing in a house with a thatch roof was associated with higher odds of malaria than residing in a house with corrugated metal (odds ratio: 2.6; 95% CI: 1.0-6.3, P = 0.04). Lower income and educational attainment were also associated with greater odds of malaria. Living under a thatch roof accounted for 24% (95% CI: 14-82) of the effect of household income on malaria risk, and income accounted for 11% (95% CI: 8-19) of the effect of education. Neither IRS nor bed net use was associated with malaria risk despite large, local investments in these vector control interventions. The findings testify to malaria as a disease of rural poverty and contribute further evidence to the utility of housing improvements in vector control programs.
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Affiliation(s)
- Jay Sikalima
- 1Tropical Diseases Research Centre, Ndola, Zambia
| | - Jessica L Schue
- 2Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,3Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Sarah E Hill
- 4Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Modest Mulenga
- 5Department of Public Health, Michael Chilufya Sata School of Medicine, Copperbelt University, Kitwe, Zambia
| | - Ray Handema
- 1Tropical Diseases Research Centre, Ndola, Zambia
| | - Victor Daka
- 5Department of Public Health, Michael Chilufya Sata School of Medicine, Copperbelt University, Kitwe, Zambia
| | | | | | | | | | - William J Moss
- 3Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Matthew M Ippolito
- 3Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
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Pinder M, Bradley J, Jawara M, Affara M, Conteh L, Correa S, Jeffries D, Jones C, Kandeh B, Knudsen J, Olatunji Y, Sicuri E, D'Alessandro U, Lindsay SW. Improved housing versus usual practice for additional protection against clinical malaria in The Gambia (RooPfs): a household-randomised controlled trial. Lancet Planet Health 2021; 5:e220-e229. [PMID: 33838737 PMCID: PMC8051018 DOI: 10.1016/s2542-5196(21)00002-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 12/21/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
BACKGROUND In malaria-endemic areas, residents of modern houses have less malaria than those living in traditional houses. We aimed to assess whether children in The Gambia received an incremental benefit from improved housing, where current best practice of insecticide-treated nets, indoor residual spraying, seasonal malaria chemoprevention in children younger than 5 years, and prompt treatment against clinical malaria was in place. METHODS In this randomised controlled study, 800 households with traditional thatched-roofed houses were randomly selected from 91 villages in the Upper River Region of The Gambia. Within each village, equal numbers of houses were randomly allocated to the control and intervention groups using a sampling frame. Houses in the intervention group were modified with metal roofs and screened doors and windows, whereas houses in the control group received no modifications. In each group, clinical malaria in children aged 6 months to 13 years was monitored by active case detection over 2 years (2016-17). We did monthly collections from indoor light traps to estimate vector densities. Primary endpoints were the incidence of clinical malaria in study children with more than 50% of observations each year and household vector density. The trial is registered at ISRCTN02622179. FINDINGS In June, 2016, 785 houses had one child each recruited into the study (398 in unmodified houses and 402 in modified houses). 26 children in unmodified houses and 28 children in modified houses did not have at least 50% of visits in a year and so were excluded from analysis. 38 children in unmodified houses were recruited after study commencement, as were 21 children in modified houses, meaning 410 children in unmodified houses and 395 in modified houses were included in the parasitological analyses. At the end of the study, 659 (94%) of 702 children were reported to have slept under an insecticide-treated net; 662 (88%) of 755 children lived in houses that received indoor residual spraying; and 151 (90%) of 168 children younger than 5 years had seasonal malaria chemoprevention. Incidence of clinical malaria was 0·12 episodes per child-year in children in the unmodified houses and 0·20 episodes per child-year in the modified houses (unadjusted incidence rate ratio [RR] 1·68 [95% CI 1·11-2·55], p=0·014). Household vector density was 3·30 Anopheles gambiae per house per night in the unmodified houses compared with 3·60 in modified houses (unadjusted RR 1·28 [0·87-1·89], p=0·21). INTERPRETATION Improved housing did not provide protection against clinical malaria in this area of low seasonal transmission with high coverage of insecticide-treated nets, indoor residual spraying, and seasonal malaria chemoprevention. FUNDING Global Health Trials funded by Medical Research Council, UK Department for International Development, and Wellcome Trust.
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Affiliation(s)
- Margaret Pinder
- Department of Biosciences, Durham University, Durham, UK; Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, UK
| | - Musa Jawara
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Muna Affara
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia; Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany
| | - Lesong Conteh
- London School of Economics and Political Science, London, UK
| | - Simon Correa
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - David Jeffries
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Caroline Jones
- KEMRI-Wellcome Trust Programme, Kilifi, Kenya and Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Balla Kandeh
- National Malaria Control Programme, Banjul, The Gambia
| | - Jakob Knudsen
- Royal Danish Academy - Architecture, Design, Conservation, Copenhagen, Denmark
| | - Yekini Olatunji
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia
| | - Elisa Sicuri
- School of Public Health, Imperial College London, London, UK; ISGlobal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, The Gambia; Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Steve W Lindsay
- Department of Biosciences, Durham University, Durham, UK; Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
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Jaiteh F, Ribera JM, Masunaga Y, Okebe J, D'Alessandro U, Balen J, Achan J, Gerrets R, Peeters Grietens K. Complexities in Defining the Unit of Intervention for Reactive Community-Based Malaria Treatment in the Gambia. Front Public Health 2021; 9:601152. [PMID: 33718317 PMCID: PMC7952428 DOI: 10.3389/fpubh.2021.601152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 02/02/2021] [Indexed: 11/24/2022] Open
Abstract
With significant declines in malaria, infections are increasingly clustered in households, or groups of households where malaria transmission is higher than in surrounding household/villages. To decrease transmission in such cases, reactive interventions target household members of clinical malaria cases, with the intervention unit (e.g., the "household/s") derived from an epidemiological and operational perspective. A lack of unanimity regarding the spatial range of the intervention unit calls for greater importance to be placed on social context in conceptualizing the appropriate unit. A novel malaria elimination strategy based on reactive treatment was recently evaluated by a cluster randomized trial in a low transmission setting in The Gambia. Transdisciplinary research was used to assess and improve the effectiveness of the intervention which consisted, among others, of reflecting on whether the household was the most adequate unit of analysis. The intervention was piloted on the smallest treatment unit possible and was further adapted following a better understanding of the social and epidemiological context. Intervention units defined according to (i) shared sleeping spaces and (ii) household membership, showed substantial limitations as it was not possible to define them clearly and they were extremely variable within the study setting. Incorporating local definitions and community preference in the trial design led to the appropriate intervention unit-the compound-defined as an enclosed space containing one or several households belonging to the same extended patrilineal family. Our study demonstrates the appropriateness of using transdisciplinary research for investigating alternative intervention units that are better tailored to reactive treatment approaches.
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Affiliation(s)
- Fatou Jaiteh
- Medical Research Council Unit the Gambia at the London School of Hygiene and Tropical Medicine, Banjul, Gambia
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Faculty of Social and Behavioural Sciences, Amsterdam Institute of Social Science Research, Amsterdam, Netherlands
| | | | - Yoriko Masunaga
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Faculty of Social and Behavioural Sciences, Amsterdam Institute of Social Science Research, Amsterdam, Netherlands
| | - Joseph Okebe
- Medical Research Council Unit the Gambia at the London School of Hygiene and Tropical Medicine, Banjul, Gambia
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Umberto D'Alessandro
- Medical Research Council Unit the Gambia at the London School of Hygiene and Tropical Medicine, Banjul, Gambia
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Julie Balen
- School of Health and Related Research (ScHARR), The University of Sheffield, Sheffield, United Kingdom
| | - Jane Achan
- Medical Research Council Unit the Gambia at the London School of Hygiene and Tropical Medicine, Banjul, Gambia
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Rene Gerrets
- Faculty of Social and Behavioural Sciences, Amsterdam Institute of Social Science Research, Amsterdam, Netherlands
| | - Koen Peeters Grietens
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- PASS Suisse, Neuchâtel, Switzerland
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
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20
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Jones RT, Ant TH, Cameron MM, Logan JG. Novel control strategies for mosquito-borne diseases. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190802. [PMID: 33357056 PMCID: PMC7776938 DOI: 10.1098/rstb.2019.0802] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2020] [Indexed: 12/23/2022] Open
Abstract
Mosquito-borne diseases are an increasing global health challenge, threatening over 40% of the world's population. Despite major advances in malaria control since 2000, recent progress has stalled. Additionally, the risk of Aedes-borne arboviruses is rapidly growing, with the unprecedented spread of dengue and chikungunya viruses, outbreaks of yellow fever and the 2015 epidemic of Zika virus in Latin America. To counteract this growing problem, diverse and innovative mosquito control technologies are currently under development. Conceptually, these span an impressive spectrum of approaches, from invasive transgene cassettes with the potential to crash mosquito populations or reduce the vectorial capacity of a population, to low-cost alterations in housing design that restrict mosquito entry. This themed issue will present articles providing insight into the breadth of mosquito control research, while demonstrating the requirement for an interdisciplinary approach. The issue will highlight mosquito control technologies at varying stages of development and includes both opinion pieces and research articles with laboratory and field-based data on control strategy development. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Robert T. Jones
- Department of Disease Control, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
| | - Thomas H. Ant
- Centre for Virus Research, Bearsden Road, Bearsden, Glasgow G61 1QH, UK
| | - Mary M. Cameron
- Department of Disease Control, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
| | - James G. Logan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
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21
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Soma DD, Zogo B, Taconet P, Somé A, Coulibaly S, Baba-Moussa L, Ouédraogo GA, Koffi A, Pennetier C, Dabiré KR, Moiroux N. Quantifying and characterizing hourly human exposure to malaria vectors bites to address residual malaria transmission during dry and rainy seasons in rural Southwest Burkina Faso. BMC Public Health 2021; 21:251. [PMID: 33516197 PMCID: PMC7847557 DOI: 10.1186/s12889-021-10304-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/21/2021] [Indexed: 11/17/2022] Open
Abstract
Background To sustain the efficacy of malaria vector control, the World Health Organization (WHO) recommends the combination of effective tools. Before designing and implementing additional strategies in any setting, it is critical to monitor or predict when and where transmission occurs. However, to date, very few studies have quantified the behavioural interactions between humans and Anopheles vectors in Africa. Here, we characterized residual transmission in a rural area of Burkina Faso where long lasting insecticidal nets (LLIN) are widely used. Methods We analysed data on both human and malaria vectors behaviours from 27 villages to measure hourly human exposure to vector bites in dry and rainy seasons using a mathematical model. We estimated the protective efficacy of LLINs and characterised where (indoors vs. outdoors) and when both LLIN users and non-users were exposed to vector bites. Results The percentage of the population who declared sleeping under a LLIN the previous night was very high regardless of the season, with an average LLIN use ranging from 92.43 to 99.89%. The use of LLIN provided > 80% protection against exposure to vector bites. The proportion of exposure for LLIN users was 29–57% after 05:00 and 0.05–12% before 20:00. More than 80% of exposure occurred indoors for LLIN users and the estimate reached 90% for children under 5 years old in the dry cold season. Conclusions LLINs are predicted to provide considerable protection against exposure to malaria vector bites in the rural area of Diébougou. Nevertheless, LLIN users are still exposed to vector bites which occurred mostly indoors in late morning. Therefore, complementary strategies targeting indoor biting vectors in combination with LLIN are expected to be the most efficient to control residual malaria transmission in this area. Supplementary Information The online version contains supplementary material available at 10.1186/s12889-021-10304-y.
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Affiliation(s)
- D D Soma
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso. .,Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso. .,MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France.
| | - B Zogo
- MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France.,Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire.,Université d'Abomey Calavi, Abomey-Calavi, Benin
| | - P Taconet
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France
| | - A Somé
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - S Coulibaly
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | | | - G A Ouédraogo
- Université Nazi Boni (UNB), Bobo-Dioulasso, Burkina Faso
| | - A Koffi
- Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire
| | - C Pennetier
- MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France.,Institut Pierre Richet (IPR), Bouaké, Côte d'Ivoire
| | - K R Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso
| | - N Moiroux
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, Burkina Faso.,MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France
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22
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Abstract
BACKGROUND Despite being preventable, malaria remains an important public health problem. The World Health Organization (WHO) reports that overall progress in malaria control has plateaued for the first time since the turn of the century. Researchers and policymakers are therefore exploring alternative and supplementary malaria vector control tools. Research in 1900 indicated that modification of houses may be effective in reducing malaria: this is now being revisited, with new research now examining blocking house mosquito entry points or modifying house construction materials to reduce exposure of inhabitants to infectious bites. OBJECTIVES To assess the effects of house modifications on malaria disease and transmission. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (PubMed); Embase (OVID); Centre for Agriculture and Bioscience International (CAB) Abstracts (Web of Science); and the Latin American and Caribbean Health Science Information database (LILACS), up to 1 November 2019. We also searched the WHO International Clinical Trials Registry Platform (www.who.int/ictrp/search/en/), ClinicalTrials.gov (www.clinicaltrials.gov), and the ISRCTN registry (www.isrctn.com/) to identify ongoing trials up to the same date. SELECTION CRITERIA Randomized controlled trials, including cluster-randomized controlled trials (cRCTs), cross-over studies, and stepped-wedge designs were eligible, as were quasi-experimental trials, including controlled before-and-after studies, controlled interrupted time series, and non-randomized cross-over studies. We only considered studies reporting epidemiological outcomes (malaria case incidence, malaria infection incidence or parasite prevalence). We also summarised qualitative studies conducted alongside included studies. DATA COLLECTION AND ANALYSIS Two review authors selected eligible studies, extracted data, and assessed the risk of bias. We used risk ratios (RR) to compare the effect of the intervention with the control for dichotomous data. For continuous data, we presented the mean difference; and for count and rate data, we used rate ratios. We presented all results with 95% confidence intervals (CIs). We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS Six cRCTs met our inclusion criteria, all conducted in sub-Saharan Africa; three randomized by household, two by village, and one at the community level. All trials assessed screening of windows, doors, eaves, ceilings or any combination of these; this was either alone, or in combination with eave closure, roof modification or eave tube installation (a "lure and kill" device that reduces mosquito entry whilst maintaining some airflow). In two trials, the interventions were insecticide-based. In five trials, the researchers implemented the interventions. The community implemented the interventions in the sixth trial. At the time of writing the review, two of the six trials had published results, both of which compared screened houses (without insecticide) to unscreened houses. One trial in Ethiopia assessed screening of windows and doors. Another trial in the Gambia assessed full screening (screening of eaves, doors and windows), as well as screening of ceilings only. Screening may reduce clinical malaria incidence caused by Plasmodium falciparum (rate ratio 0.38, 95% CI 0.18 to 0.82; 1 trial, 184 participants, 219.3 person-years; low-certainty evidence; Ethiopian study). For malaria parasite prevalence, the point estimate, derived from The Gambia study, was smaller (RR 0.84, 95% CI 0.60 to 1.17; 713 participants, 1 trial; low-certainty evidence), and showed an effect on anaemia (RR 0.61, 95% CI 0.42, 0.89; 705 participants; 1 trial, moderate-certainty evidence). Screening may reduce the entomological inoculation rate (EIR): both trials showed lower estimates in the intervention arm. In the Gambian trial, there was a mean difference in EIR between the control houses and treatment houses ranging from 0.45 to 1.50 (CIs ranged from -0.46 to 2.41; low-certainty evidence), depending on the study year and treatment arm. The Ethiopian trial reported a mean difference in EIR of 4.57, favouring screening (95% CI 3.81 to 5.33; low-certainty evidence). Pooled analysis of the trials showed that individuals living in fully screened houses were slightly less likely to sleep under a bed net (RR 0.84, 95% CI 0.65 to 1.09; 2 trials, 203 participants). In one trial, bed net usage was also lower in individuals living in houses with screened ceilings (RR 0.69, 95% CI 0.50 to 0.95; 1 trial, 135 participants). AUTHORS' CONCLUSIONS Based on the two trials published to date, there is some evidence that screening may reduce malaria transmission and malaria infection in people living in the house. The four trials awaiting publication are likely to enrich the current evidence base, and we will add these to this review when they become available.
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Affiliation(s)
- Joanna Furnival-Adams
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Evelyn A Olanga
- Malaria Alert Centre of the College of Medicine, Blantyre, Malawi
| | - Mark Napier
- Council for Scientific and Industrial Research, Pretoria, South Africa
- Centre for Development Support, University of the Free State, Bloemfontein, South Africa
| | - Paul Garner
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
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23
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Kua KP, Lee SWH. Randomized trials of housing interventions to prevent malaria and Aedes-transmitted diseases: A systematic review and meta-analysis. PLoS One 2021; 16:e0244284. [PMID: 33417600 PMCID: PMC7793286 DOI: 10.1371/journal.pone.0244284] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 12/08/2020] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Mosquito-borne diseases remain a significant public health problem in tropical regions. Housing improvements such as screening of doors and windows may be effective in reducing disease transmission, but the impact remains unclear. OBJECTIVES To examine whether housing interventions were effective in reducing mosquito densities in homes and the impact on the incidence of mosquito-borne diseases. METHODS In this systematic review and meta-analysis, we searched 16 online databases, including NIH PubMed, CINAHL Complete, LILACS, Ovid MEDLINE, and Cochrane Central Register of Controlled Trials for randomized trials published from database inception to June 30, 2020. The primary outcome was the incidence of any mosquito-borne diseases. Secondary outcomes encompassed entomological indicators of the disease transmission. I2 values were used to explore heterogeneity between studies. A random-effects meta-analysis was used to assess the primary and secondary outcomes, with sub-group analyses for type of interventions on home environment, study settings (rural, urban, or mixed), and overall house type (traditional or modern housing). RESULTS The literature search yielded 4,869 articles. After screening, 18 studies were included in the qualitative review, of which nine were included in the meta-analysis. The studies enrolled 7,200 households in Africa and South America, reporting on malaria or dengue only. The type of home environmental interventions included modification to ceilings and ribbons to close eaves, screening doors and windows with nets, insecticide-treated wall linings in homes, nettings over gables and eaves openings, mosquito trapping systems, metal-roofed houses with mosquito screening, gable windows and closed eaves, and prototype houses using southeast Asian designs. Pooled analysis depicted a lower risk of mosquito-borne diseases in the housing intervention group (OR = 0.68; 95% CI = 0.48 to 0.95; P = 0.03). Subgroup analysis depicted housing intervention reduced the risk of malaria in all settings (OR = 0.63; 95% CI = 0.39 to 1.01; P = 0.05). In urban environment, housing intervention was found to decrease the risk of both malaria and dengue infections (OR = 0.52; 95% CI = 0.27 to 0.99; P = 0.05).Meta-analysis of pooled odds ratio showed a significant benefit of improved housing in reducing indoor vector densities of both Aedes and Anopheles (OR = 0.35; 95% CI = 0.23 to 0.54; P<0.001). CONCLUSIONS Housing intervention could reduce transmission of malaria and dengue among people living in the homes. Future research should evaluate the protective effect of specific house features and housing improvements associated with urban development.
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Affiliation(s)
- Kok Pim Kua
- Puchong Health Clinic, Petaling District Health Office, Ministry of Health Malaysia, Petaling, Malaysia
| | - Shaun Wen Huey Lee
- School of Pharmacy, Monash University Malaysia, Sunway City, Malaysia
- Asian Center for Evidence Synthesis in Population, Implementation, and Clinical Outcomes (PICO), Health and Well-being Cluster, Global Asia in the 21st Century (GA21) Platform, Monash University Malaysia, Sunway City, Malaysia
- Gerontechnology Laboratory, Global Asia in the 21st Century (GA21) Platform, Monash University Malaysia, Sunway City, Malaysia
- Faculty of Health and Medical Sciences, Taylor's University, Subang Jaya, Malaysia
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Lindsay SW, Davies M, Alabaster G, Altamirano H, Jatta E, Jawara M, Carrasco-Tenezaca M, von Seidlein L, Shenton FC, Tusting LS, Wilson AL, Knudsen J. Recommendations for building out mosquito-transmitted diseases in sub-Saharan Africa: the DELIVER mnemonic. Philos Trans R Soc Lond B Biol Sci 2020; 376:20190814. [PMID: 33357059 DOI: 10.1098/rstb.2019.0814] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
In sub-Saharan Africa, most transmission of mosquito-transmitted diseases, such as malaria or dengue, occurs within or around houses. Preventing mosquito house entry and reducing mosquito production around the home would help reduce the transmission of these diseases. Based on recent research, we make key recommendations for reducing the threat of mosquito-transmitted diseases through changes to the built environment. The mnemonic, DELIVER, recommends the following best practices: (i) Doors should be screened, self-closing and without surrounding gaps; (ii) Eaves, the space between the wall and roof, should be closed or screened; (iii) houses should be Lifted above the ground; (iv) Insecticide-treated nets should be used when sleeping in houses at night; (v) houses should be Ventilated, with at least two large-screened windows to facilitate airflow; (vi) Environmental management should be conducted regularly inside and around the home; and (vii) Roofs should be solid, rather than thatch. DELIVER is a package of interventions to be used in combination for maximum impact. Simple changes to the built environment will reduce exposure to mosquito-transmitted diseases and help keep regions free from these diseases after elimination. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Steven W Lindsay
- Department of Biosciences, Durham University, Durham DH1 3LE, UK
| | - Michael Davies
- Bartlett School Environment, Energy & Resources, Faculty of the Built Environment, University College London, London WC1H 0NN, UK
| | | | - Hector Altamirano
- Bartlett School Environment, Energy & Resources, Faculty of the Built Environment, University College London, London WC1H 0NN, UK
| | - Ebrima Jatta
- National Malaria Control Programme, Banjul, The Gambia
| | - Musa Jawara
- Medical Research Council Unit Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | | | - Lorenz von Seidlein
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Fiona C Shenton
- Department of Biosciences, Durham University, Durham DH1 3LE, UK
| | - Lucy S Tusting
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Anne L Wilson
- Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Jakob Knudsen
- The Royal Danish Academy of Fine Arts, School of Architecture, Design and Conservation, The School of Architecture, Copenhagen, Denmark
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25
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Abstract
BACKGROUND Despite being preventable, malaria remains an important public health problem. The World Health Organization (WHO) reports that overall progress in malaria control has plateaued for the first time since the turn of the century. Researchers and policymakers are therefore exploring alternative and supplementary malaria vector control tools. Research in 1900 indicated that modification of houses may be effective in reducing malaria: this is now being revisited, with new research now examining blocking house mosquito entry points or modifying house construction materials to reduce exposure of inhabitants to infectious bites. OBJECTIVES To assess the effects of house modifications on malaria disease and transmission. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; MEDLINE (PubMed); Embase (OVID); Centre for Agriculture and Bioscience International (CAB) Abstracts (Web of Science); and the Latin American and Caribbean Health Science Information database (LILACS), up to 1 November 2019. We also searched the WHO International Clinical Trials Registry Platform (www.who.int/ictrp/search/en/), ClinicalTrials.gov (www.clinicaltrials.gov), and the ISRCTN registry (www.isrctn.com/) to identify ongoing trials up to the same date. SELECTION CRITERIA Randomized controlled trials, including cluster-randomized controlled trials (cRCTs), cross-over studies, and stepped-wedge designs were eligible, as were quasi-experimental trials, including controlled before-and-after studies, controlled interrupted time series, and non-randomized cross-over studies. We only considered studies reporting epidemiological outcomes (malaria case incidence, malaria infection incidence or parasite prevalence). We also summarised qualitative studies conducted alongside included studies. DATA COLLECTION AND ANALYSIS Two review authors selected eligible studies, extracted data, and assessed the risk of bias. We used risk ratios (RR) to compare the effect of the intervention with the control for dichotomous data. For continuous data, we presented the mean difference; and for count and rate data, we used rate ratios. We presented all results with 95% confidence intervals (CIs). We assessed the certainty of evidence using the GRADE approach. MAIN RESULTS Six cRCTs met our inclusion criteria, all conducted in sub-Saharan Africa; three randomized by household, two by village, and one at the community level. All trials assessed screening of windows, doors, eaves, ceilings or any combination of these; this was either alone, or in combination with eave closure, roof modification or eave tube installation (a "lure and kill" device that reduces mosquito entry whilst maintaining some airflow). In two trials, the interventions were insecticide-based. In five trials, the researchers implemented the interventions. The community implemented the interventions in the sixth trial. At the time of writing the review, two of the six trials had published results, both of which compared screened houses (without insecticide) to unscreened houses. One trial in Ethiopia assessed screening of windows and doors. Another trial in the Gambia assessed full screening (screening of eaves, doors and windows), as well as screening of ceilings only. Screening may reduce clinical malaria incidence caused by Plasmodium falciparum (rate ratio 0.38, 95% CI 0.18 to 0.82; 1 trial, 184 participants, 219.3 person-years; low-certainty evidence; Ethiopian study). For malaria parasite prevalence, the point estimate, derived from The Gambia study, was smaller (RR 0.84, 95% CI 0.60 to 1.17; 713 participants, 1 trial; moderate-certainty evidence), and showed an effect on anaemia (RR 0.61, 95% CI 0.42, 0.89; 705 participants; 1 trial, moderate-certainty evidence). Screening may reduce the entomological inoculation rate (EIR): both trials showed lower estimates in the intervention arm. In the Gambian trial, there was a mean difference in EIR between the control houses and treatment houses ranging from 0.45 to 1.50 (CIs ranged from -0.46 to 2.41; low-certainty evidence), depending on the study year and treatment arm. The Ethiopian trial reported a mean difference in EIR of 4.57, favouring screening (95% CI 3.81 to 5.33; low-certainty evidence). Pooled analysis of the trials showed that individuals living in fully screened houses were slightly less likely to sleep under a bed net (RR 0.84, 95% CI 0.65 to 1.09; 2 trials, 203 participants). In one trial, bed net usage was also lower in individuals living in houses with screened ceilings (RR 0.69, 95% CI 0.50 to 0.95; 1 trial, 135 participants). AUTHORS' CONCLUSIONS Based on the two trials published to date, there is some evidence that screening may reduce malaria transmission and malaria infection in people living in the house. The four trials awaiting publication are likely to enrich the current evidence base, and we will add these to this review when they become available.
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Affiliation(s)
- Joanna Furnival-Adams
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Evelyn A Olanga
- Malaria Alert Centre of the College of Medicine, Blantyre, Malawi
| | - Mark Napier
- Council for Scientific and Industrial Research, Pretoria, South Africa
- Centre for Development Support, University of the Free State, Bloemfontein, South Africa
| | - Paul Garner
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
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Knudsen JB, Pinder M, Jatta E, Jawara M, Yousuf MA, Søndergaard AT, Lindsay SW. Measuring ventilation in different typologies of rural Gambian houses: a pilot experimental study. Malar J 2020; 19:273. [PMID: 32736629 PMCID: PMC7393878 DOI: 10.1186/s12936-020-03327-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/07/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND African houses are frequently too hot and uncomfortable to use a bed net at night. Indoor thermal comfort is often evaluated by measuring temperature and humidity, ignoring ventilation. This study explored ways to measure ventilation in single-roomed rural Gambian houses during the malaria transmission season and evaluated building designs that could increase airflow at night and help keep the occupants comfortable. METHODS Two identical mud-walled houses were constructed with a metal roof, three doors and closed eaves. Experiment 1 compared five methods for measuring ventilation in a building: (1) using a blower door, (2) increasing carbon dioxide (CO2) levels indoors using an artificial source of CO2 and then measuring the rate of gas decay, (3) using a similar approach with a natural source of CO2, (4) measuring the rise of CO2 when people enter a building and (5) using hot-wire anemometers. Experiment 2 used CO2 data loggers to compare ventilation in a reference metal-roofed house with closed eaves and badly-fitting doors with a similar house with (1) thatched roof and open eaves, (2) eaves tubes, (3) screened doors and (4) screened doors and windows. RESULTS In experiment 1, CO2 data loggers placed indoors in two identical houses showed similar changes in airflow (p > 0.05) for all three methods recording either decreasing or increasing CO2. Blower doors were unable to measure airflow in houses with open eaves or screened windows and the anemometers broke down under field conditions. In experiment 2, open eaves in thatched houses, screened doors alone, and screened doors and windows increased indoor ventilation compared to the reference metal-roofed house with closed eaves and badly fitting doors (p < 0.05). Eaves tubes did not increase ventilation in comparison to the reference house. CONCLUSION CO2 data loggers proved to be a simple and efficient method for measuring ventilation in rural houses at night. Ventilation of metal-roofed houses can be improved by adding two screened doors and windows on opposite walls. Improved ventilation will result in increased thermal comfort making it more likely that people will sleep under a bed net.
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Affiliation(s)
- Jakob B Knudsen
- Schools of Architecture, Design and Conservation, The Royal Danish Academy of Fine Arts, Philip de Langes Allé 10, 1435, Copenhagen K, Denmark.
| | - Margaret Pinder
- Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Fajara, The Gambia.,Department of Biosciences, Durham University, Durham, UK
| | - Ebrima Jatta
- Department of Biosciences, Durham University, Durham, UK.,National Malaria Control Programme, Banjul, The Gambia
| | - Musa Jawara
- Medical Research Council Unit, The Gambia at the London School of Hygiene & Tropical Medicine, Fajara, The Gambia
| | - Mahamed A Yousuf
- Schools of Architecture, Design and Conservation, The Royal Danish Academy of Fine Arts, Philip de Langes Allé 10, 1435, Copenhagen K, Denmark
| | - Amalie T Søndergaard
- Schools of Architecture, Design and Conservation, The Royal Danish Academy of Fine Arts, Philip de Langes Allé 10, 1435, Copenhagen K, Denmark
| | - Steve W Lindsay
- Department of Biosciences, Durham University, Durham, UK.,London School of Hygiene & Tropical Medicine, London, UK
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27
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Tusting LS, Gething PW, Gibson HS, Greenwood B, Knudsen J, Lindsay SW, Bhatt S. Housing and child health in sub-Saharan Africa: A cross-sectional analysis. PLoS Med 2020; 17:e1003055. [PMID: 32203504 PMCID: PMC7089421 DOI: 10.1371/journal.pmed.1003055] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 02/19/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Housing is essential to human well-being but neglected in global health. Today, housing in Africa is rapidly improving alongside economic development, creating an urgent need to understand how these changes can benefit health. We hypothesised that improved housing is associated with better health in children living in sub-Saharan Africa (SSA). We conducted a cross-sectional analysis of housing conditions relative to a range of child health outcomes in SSA. METHODS AND FINDINGS Cross-sectional data were analysed for 824,694 children surveyed in 54 Demographic and Health Surveys, 21 Malaria Indicator Surveys, and two AIDS Indicator Surveys conducted in 33 countries between 2001 and 2017 that measured malaria infection by microscopy or rapid diagnostic test (RDT), diarrhoea, acute respiratory infections (ARIs), stunting, wasting, underweight, or anaemia in children aged 0-5 years. The mean age of children was 2.5 years, and 49.7% were female. Housing was categorised into a binary variable based on a United Nations definition comparing improved housing (with improved drinking water, improved sanitation, sufficient living area, and finished building materials) versus unimproved housing (all other houses). Associations between house type and child health outcomes were determined using conditional logistic regression within surveys, adjusting for prespecified covariables including age, sex, household wealth, insecticide-treated bed net use, and vaccination status. Individual survey odds ratios (ORs) were pooled using random-effects meta-analysis. Across surveys, improved housing was associated with 8%-18% lower odds of all outcomes except ARI (malaria infection by microscopy: adjusted OR [aOR] 0.88, 95% confidence intervals [CIs] 0.80-0.97, p = 0.01; malaria infection by RDT: aOR 0.82, 95% CI 0.77-0.88, p < 0.001; diarrhoea: aOR 0.92, 95% CI 0.88-0.97, p = 0.001; ARI: aOR 0.96, 95% CI 0.87-1.07, p = 0.49; stunting: aOR 0.83, 95% CI 0.77-0.88, p < 0.001; wasting: aOR 0.90, 95% CI 0.83-0.99, p = 0.03; underweight: aOR 0.85, 95% CI 0.80-0.90, p < 0.001; any anaemia: aOR 0.87, 95% CI 0.82-0.92, p < 0.001; severe anaemia: aOR 0.89, 95% CI 0.84-0.95, p < 0.001). In comparison, insecticide-treated net use was associated with 16%-17% lower odds of malaria infection (microscopy: aOR 0.83, 95% CI 0.78-0.88, p < 0.001; RDT: aOR 0.84, 95% CI 0.79-0.88, p < 0.001). Drinking water source and sanitation facility alone were not associated with diarrhoea. The main study limitations are the use of self-reported diarrhoea and ARI, as well as potential residual confounding by socioeconomic position, despite adjustments for household wealth and education. CONCLUSIONS In this study, we observed that poor housing, which includes inadequate drinking water and sanitation facility, is associated with health outcomes known to increase child mortality in SSA. Improvements to housing may be protective against a number of important childhood infectious diseases as well as poor growth outcomes, with major potential to improve children's health and survival across SSA.
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Affiliation(s)
- Lucy S. Tusting
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Peter W. Gething
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Harry S. Gibson
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Brian Greenwood
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Jakob Knudsen
- The Royal Danish Academy of Fine Arts, Schools of Architecture, Design and Conservation, Copenhagen, Denmark
| | - Steve W. Lindsay
- Department of Biosciences, Durham University, Durham, United Kingdom
| | - Samir Bhatt
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, United Kingdom
- Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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Clustering of asymptomatic Plasmodium falciparum infection and the effectiveness of targeted malaria control measures. Malar J 2020; 19:33. [PMID: 31964378 PMCID: PMC6975028 DOI: 10.1186/s12936-019-3063-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 12/08/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Because clustering of Plasmodium falciparum infection had been noted previously, the clustering of infection was examined at four field sites in West Africa: Dangassa and Dioro in Mali, Gambissara in The Gambia and Madina Fall in Senegal. METHODS Clustering of infection was defined by the percent of persons with positive slides for asexual P. falciparum sleeping in a house which had been geopositioned. Data from each site were then tested for spatial, temporal and spatio-temporal clustering in relation to the prevalence of infection from smear surveys. RESULTS These studies suggest that clustering of P. falciparum infection also affects the effectiveness of control interventions. For example, the clustering of infection in Madina Fall disappeared in 2014-2016 after vector control eliminated the only breeding site in 2013. In contrast, the temporal clustering of infection in Dioro (rainy season of 2014, dry season of 2015) was consistent with the loss of funding for Dioro in the second quarter of 2014 and disappeared when funds again became available in late 2015. The clustering of infection in rural (western) areas of Gambissara was consistent with known rural-urban differences in the prevalence of infection and with the thatched roofs, open eaves and mud walls of houses in rural Gambissara. In contrast, the most intense transmission was in Dangassa, where the only encouraging observation was a lower prevalence of infection in the dry season. Taken together, these results suggest: (a) the transmission of infection was stopped in Madina Fall by eliminating the only known breeding site, (b) the prevalence of infection was reduced in Dioro after financial support became available again for malaria control in the second half of 2015, (c) improvements in housing should improve malaria control by reducing the number of vectors in rural communities such as western Gambissara, and (d) beginning malaria control during the dry season may reduce transmission in hyperendemic areas such as Dangassa. CONCLUSIONS From a conceptual perspective, testing for spatial, temporal and spatio-temporal clustering based on epidemiologic data permits the generation of hypotheses for the clustering observed and the testing of candidate interventions to confirm or refute those hypotheses.
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29
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Msugupakulya BJ, Kaindoa EW, Ngowo HS, Kihonda JM, Kahamba NF, Msaky DS, Matoke-Muhia D, Tungu PK, Okumu FO. Preferred resting surfaces of dominant malaria vectors inside different house types in rural south-eastern Tanzania. Malar J 2020; 19:22. [PMID: 31941508 PMCID: PMC6964015 DOI: 10.1186/s12936-020-3108-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 01/07/2020] [Indexed: 02/04/2023] Open
Abstract
Background Malaria control in Africa relies extensively on indoor residual spraying (IRS) and insecticide-treated nets (ITNs). IRS typically targets mosquitoes resting on walls, and in few cases, roofs and ceilings, using contact insecticides. Unfortunately, little attention is paid to where malaria vectors actually rest indoors, and how such knowledge could be used to improve IRS. This study investigated preferred resting surfaces of two major malaria vectors, Anopheles funestus and Anopheles arabiensis, inside four common house types in rural south-eastern Tanzania. Methods The assessment was done inside 80 houses including: 20 with thatched roofs and mud walls, 20 with thatched roofs and un-plastered brick walls, 20 with metal roofs and un-plastered brick walls, and 20 with metal roofs and plastered brick walls, across four villages. In each house, resting mosquitoes were sampled in mornings (6 a.m.–8 a.m.), evenings (6 p.m.–8 p.m.) and at night (11 p.m.–12.00 a.m.) using Prokopack aspirators from multiple surfaces (walls, undersides of roofs, floors, furniture, utensils, clothing, curtains and bed nets). Results Overall, only 26% of An. funestus and 18% of An. arabiensis were found on walls. In grass-thatched houses, 33–55% of An. funestus and 43–50% of An. arabiensis rested under roofs, while in metal-roofed houses, only 16–20% of An. funestus and 8–30% of An. arabiensis rested under roofs. Considering all data together, approximately 40% of mosquitoes rested on surfaces not typically targeted by IRS, i.e. floors, furniture, utensils, clothing and bed nets. These proportions were particularly high in metal-roofed houses (47–53% of An. funestus; 60–66% of An. arabiensis). Conclusion While IRS typically uses contact insecticides to target adult mosquitoes on walls, and occasionally roofs and ceilings, significant proportions of vectors rest on surfaces not usually sprayed. This gap exceeds one-third of malaria mosquitoes in grass-thatched houses, and can reach two-thirds in metal-roofed houses. Where field operations exclude roofs during IRS, the gaps can be much greater. In conclusion, there is need for locally-obtained data on mosquito resting behaviours and how these influence the overall impact and costs of IRS. This study also emphasizes the need for alternative approaches, e.g. house screening, which broadly tackle mosquitoes beyond areas reachable by IRS and ITNs.
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Affiliation(s)
- Betwel J Msugupakulya
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania. .,School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania.
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Japhet M Kihonda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Najat F Kahamba
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania
| | - Dickson S Msaky
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania
| | - Damaris Matoke-Muhia
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania.,Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Patrick K Tungu
- Amani Medical Research Centre, National Institute of Medical Research, Muheza, Tanzania
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P. O. Box 53, Ifakara, Tanzania. .,School of Life Science and Bioengineering, The Nelson Mandela African Institution of Science and Technology, P. O. Box 447, Arusha, Tanzania. .,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. .,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
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30
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Furnival‐Adams J, Olanga EA, Napier M, Garner P. Housing interventions for preventing malaria. Cochrane Database Syst Rev 2019; 2019:CD013398. [PMCID: PMC6691978 DOI: 10.1002/14651858.cd013398] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: Primary To assess the effects of different structural house modifications on malaria disease burden. Secondary To explore whether effects vary with level of transmission.
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Affiliation(s)
| | - Evelyn A Olanga
- Malaria Alert Centre of the College of MedicineQueen Elizabeth Hospital Grounds, Ginnery cornerBlantyreMalawi
| | - Mark Napier
- Council for Scientific and Industrial ResearchBuilt EnvironmentPretoriaSouth Africa
| | - Paul Garner
- Liverpool School of Tropical MedicineDepartment of Clinical SciencesLiverpoolUK
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