Proximity of Residence to Irrigation Determines Malaria Risk and Anopheles Abundance at an Irrigated Agroecosystem in Malawi

Mangani, Charles; Frake, April N.; Chipula, Grivin; Mkwaila, Wezi; Kakota, Tasokwa; Mambo, Isaac; Chingonda, Jerome; Mathanga, Don P.; Mzilahowa, Themba; Zulu, Leo C.; Walker, Edward D.

doi:10.4269/ajtmh.21-0390

Cited by 20 publications

(15 citation statements)

References 60 publications

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“…This study also revealed short walk time distance (0–15 min) to water sources was one of the risk factors for malaria among children. This result is in line with other studies focusing on malaria infections and distance to water sources [ 52 , 53 ]. Although distant water sources were associated with reduced malaria risk, this result should not hamper efforts geared to improve water access in refugee settlements.…”

Section: Discussionsupporting

confidence: 93%

Determinants of malaria infections among children in refugee settlements in Uganda during 2018–2019

et al. 2023

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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. Graphical Abstract

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Section: Discussionsupporting

confidence: 93%

Determinants of malaria infections among children in refugee settlements in Uganda during 2018–2019

et al. 2023

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“…Forty-one (41) studies were conducted in 20 countries in SSA. The review had eight studies conducted in Tanzania [ 21 , 23 , 28 – 33 ], and Malawi [ 23 , 34 – 40 ] and seven studies from Uganda [ 1 , 22 , 23 , 25 , 41 – 43 ], four in Ethiopia [ 18 , 19 , 44 , 45 ], three in Kenya [ 46 – 48 ], two in Ghana [ 27 , 49 ], the Gambia [ 27 , 49 ], and Burkina Faso [ 49 , 50 ], Democratic Republic of Congo (DRC) [ 51 , 52 ], Nigeria [ 23 , 53 ], Mali [ 49 , 54 ], Mozambique [ 55 , 56 ], while Cameroon [ 57 ], Equatorial Guinea [ 24 ], Angola [ 23 ], Liberia [ 23 ], Rwanda [ 23 ], Senegal [ 23 ], Madagascar [ 23 ] and South Africa [ 20 ] all had one study.…”

Section: Resultsmentioning

confidence: 99%

What are the pathways between poverty and malaria in sub-Saharan Africa? A systematic review of mediation studies

et al. 2023

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Background Malaria remains a major burden in sub-Saharan Africa (SSA). While an association between poverty and malaria has been demonstrated, a clearer understanding of explicit mechanisms through which socioeconomic position (SEP) influences malaria risk is needed to guide the design of more comprehensive interventions for malaria risk mitigation. This systematic review provides an overview of the current evidence on the mediators of socioeconomic disparities in malaria in SSA. Methods We searched PubMed and Web of Science for randomised controlled trials, cohort, case-control and cross-sectional studies published in English between January 1, 2000 to May 31, 2022. Further studies were identified following reviews of reference lists of the studies included. We included studies that either (1) conducted a formal mediation analysis of risk factors on the causal pathway between SEP and malaria infections or (2) adjusted for these potential mediators as confounders on the association between SEP and malaria using standard regression models. At least two independent reviewers appraised the studies, conducted data extraction, and assessed risk of bias. A systematic overview is presented for the included studies. Results We identified 41 articles from 20 countries in SSA for inclusion in the final review. Of these, 30 studies used cross-sectional design, and 26 found socioeconomic inequalities in malaria risk. Three formal mediation analyses showed limited evidence of mediation of food security, housing quality, and previous antimalarial use. Housing, education, insecticide-treated nets, and nutrition were highlighted in the remaining studies as being protective against malaria independent of SEP, suggesting potential for mediation. However, methodological limitations included the use of cross-sectional data, insufficient confounder adjustment, heterogeneity in measuring both SEP and malaria, and generally low or moderate-quality studies. No studies considered exposure mediator interactions or considered identifiability assumptions. Conclusions Few studies have conducted formal mediation analyses to elucidate pathways between SEP and malaria. Findings indicate that food security and housing could be more feasible (structural) intervention targets. Further research using well-designed longitudinal studies and improved analysis would illuminate the current sparse evidence into the pathways between SEP and malaria and adduce evidence for more potential targets for effective intervention. Graphical Abstract

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“…The general interplay between irrigation and malaria in Africa is well-understood but the relationship is complex and depends on the agroecosystem, socio-economic factors, local vector behaviour and ecology, and the seasonality of disease 12,13 . Efforts to characterise this relationship in Malawi have been performed in a commercial sugar growing estate and within an irrigated rice valley 14,15 , and research is underway to do the same within a World Bank funded large-scale transformation programme 16 . These systems are, however, much larger and concentrated on a single geographic area.…”

Section: Introductionmentioning

confidence: 99%

Small dams driveAnophelesabundance during the dry season in a high malaria burden area of Malawi

Zembere,

Jones,

Mthawanji

et al. 2023

Preprint

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This study explores the influence of small dams on the exposure to malaria vectors during the dry season in Kasungu district, Malawi, an area recently identified as high priority for malaria interventions by the National Malaria Control Programme. Small dam impoundments provide communities with a continuous supply of water for domestic and agricultural activities across sub-Saharan Africa and are considered vital to food security and climate change resilience. However, these permanent water bodies also create ideal breeding sites for mosquitoes in typically arid landscapes. The study focuses on a specific dam impoundment and its vicinity, aiming to assess its spatial and temporal influence on indoor vector densities.Throughout May to August 2021, CDC light traps were used to measure indoor mosquito densities for two consecutive nights per month in three communities located at increasing distances from the dam (0km, ∼1km, ∼2km). Simultaneously, drone imagery was captured for each community, enabling the identification of additional standing water within approximately 400 meters of selected households. Larval sampling was carried out within the impoundment periphery and in additional water bodies identified in the drone imagery. Generalised linear mixed models (GLMMs) were employed to analyse the indoorAnophelesabundance data, estimating the effects of household structure (open/closed eaves), month, temperature, and water proximity on malaria vector exposure.Throughout 685 trapping nights, a total of 1,256 mosquitoes were captured, with 33% (412) being femaleAnopheles. Among these, 91% were morphologically identified asAn. funestuss.l., and 5% asAn. gambiaes.l. Catches progressively declines in each consecutive trapping month as the environment became drier. This decline was much slower in Malangano, the community next to the dam, with abundance being notably higher in June and July. Further, the majority ofAn. gambiaes.l. were caught in May, with none identified in July and August.Anopheleslarvae were found both in the impoundment and other smaller water bodies such as irrigation wells in each survey month, however the presence of these smaller water bodies did not have a significant impact on adult female mosquito catches in the GLMM. The study concludes that proximity to the dam impoundment was the primary driver of differences between survey communities with the abundance in Chikhombwe (∼1km away) and Chiponde (∼2km away) being 0.35 (95% CI 0.19-0.66) and 0.28 (95% CI 0.16-0.47) lower than Malangano respectively after adjusting for other factors.These findings underscore the importance of targeted interventions, such as larval source management or housing improvements, near small dams to mitigate malaria transmission risks during the dry season. Further research is needed to develop cost-effective strategies for vector control within and around these impoundments.

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Proximity of Residence to Irrigation Determines Malaria Risk and Anopheles Abundance at an Irrigated Agroecosystem in Malawi

Cited by 20 publications

References 60 publications

Determinants of malaria infections among children in refugee settlements in Uganda during 2018–2019

Determinants of malaria infections among children in refugee settlements in Uganda during 2018–2019

What are the pathways between poverty and malaria in sub-Saharan Africa? A systematic review of mediation studies

Small dams driveAnophelesabundance during the dry season in a high malaria burden area of Malawi

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