Remote sensing of environmental risk factors for malaria in different geographic contexts

Abstract Background Despite global intervention efforts, malaria remains a major public health concern in many parts of the world. Understanding geographic variation in malaria patterns and their environmental determinants can support targeting of malaria control and development of elimination strategies. We used multiple sources of remotely-sensed environmental data to analyze the influences of environmental risk factors on malaria cases caused by Plasmodium falciparum and Plasmodium vivax in two geographic settings in Ethiopia. Results We found considerable spatial variation in malaria proportion and the distribution of malaria hot spots. Spectral indices were related to land cover greenness (NDVI) and moisture (NDWI) showed an association between malaria and dry landscapes. Climatic factors, including precipitation and land surface temperature, had positive associations with malaria occurrence. Settlement structure also played an important role, with opposing relationships between settlement density and malaria for the two study areas. Variables related to land surface water, such as irrigated agriculture, wetlands, seasonally flooded waterbodies and height above nearest drainage did not influence malaria proportion. Conclusion We found different relationships between malaria and environmental conditions in two geographically distinctive areas. These results emphasize that studies of malaria-environmental relationships and predictive models of malaria occurence should be context specific to account for such differences.

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Remote sensing of environmental risk factors for malaria in different geographic contexts

International Journal of Health Geographics ◽

10.1186/s12942-021-00282-0 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Andrea McMahon ◽

Abere Mihretie ◽

Adem Agmas Ahmed ◽

Mastewal Lake ◽

Worku Awoke ◽

...

Keyword(s):

Risk Factors ◽

Surface Water ◽

Environmental Risk ◽

Land Surface ◽

Climatic Factors ◽

Environmental Risk Factors ◽

Environmental Data ◽

Health Concern ◽

Irrigated Agriculture ◽

Boosted Regression Tree

Abstract Background Despite global intervention efforts, malaria remains a major public health concern in many parts of the world. Understanding geographic variation in malaria patterns and their environmental determinants can support targeting of malaria control and development of elimination strategies. Methods We used remotely sensed environmental data to analyze the influences of environmental risk factors on malaria cases caused by Plasmodium falciparum and Plasmodium vivax from 2014 to 2017 in two geographic settings in Ethiopia. Geospatial datasets were derived from multiple sources and characterized climate, vegetation, land use, topography, and surface water. All data were summarized annually at the sub-district (kebele) level for each of the two study areas. We analyzed the associations between environmental data and malaria cases with Boosted Regression Tree (BRT) models. Results We found considerable spatial variation in malaria occurrence. Spectral indices related to land cover greenness (NDVI) and moisture (NDWI) showed negative associations with malaria, as the highest malaria rates were found in landscapes with low vegetation cover and moisture during the months that follow the rainy season. Climatic factors, including precipitation and land surface temperature, had positive associations with malaria. Settlement structure also played an important role, with different effects in the two study areas. Variables related to surface water, such as irrigated agriculture, wetlands, seasonally flooded waterbodies, and height above nearest drainage did not have strong influences on malaria. Conclusion We found different relationships between malaria and environmental conditions in two geographically distinctive areas. These results emphasize that studies of malaria-environmental relationships and predictive models of malaria occurrence should be context specific to account for such differences.

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Large Lemurs: Ecological, Demographic and Environmental Risk Factors for Weight Gain in Captivity

Animals ◽

10.3390/ani10081443 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1443

Author(s):

Emma L. Mellor ◽

Innes C. Cuthill ◽

Christoph Schwitzer ◽

Georgia J. Mason ◽

Michael Mendl

Keyword(s):

Risk Factors ◽

Weight Gain ◽

Environmental Risk ◽

Food Resource ◽

Potential Ecological Risk ◽

Environmental Risk Factors ◽

Health Concern ◽

Wild Food ◽

Future Research ◽

In Captivity

Excessive body mass, i.e., being overweight or obese, is a health concern associated with issues such as reduced fertility and lifespan. Some lemur species are prone to extreme weight gain in captivity, yet others are not. To better understand species- and individual-level effects on susceptibility to captive weight gain, we use two complementary methods: phylogenetic comparative methods to examine ecological explanations for susceptibility to weight gain across species, and epidemiological approaches to examine demographic and environment effects within species. Data on body masses and living conditions were collected using a survey, yielding useable data on 675 lemurs representing 13 species from 96 collections worldwide. Data on species-typical wild ecology for comparative analyses came from published literature and climate databases. We uncovered one potential ecological risk factor: species adapted to greater wild food resource unpredictability tended to be more prone to weight gain. Our epidemiological analyses on the four best-sampled species revealed four demographic and one environmental risk factors, e.g., for males, being housed with only fixed climbing structures. We make practical recommendations to help address weight concerns, and describe future research including ways to validate the proxy we used to infer body condition.

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Environmental Factors and Prevalence of Hookworm infection and Strongyloidiasis in Rural East Kalimantan, Indonesia

E3S Web of Conferences ◽

10.1051/e3sconf/201912504001 ◽

2019 ◽

Vol 125 ◽

pp. 04001

Author(s):

Blego Sedionoto ◽

Sueptrakool Wasessombat ◽

Chuchard Punsawad ◽

Witthaya Anamnart

Keyword(s):

Risk Factors ◽

Environmental Factors ◽

Rural Community ◽

Environmental Risk ◽

Environmental Risk Factors ◽

Diagnostic Methods ◽

Health Concern ◽

Hookworm Infection ◽

East Kalimantan ◽

Chi Square Analysis

The prevalence of hookworm infection and strongyloidiasis is serious public health concern globally. In rural East Kalimantan, Indonesia has high-risk environmental factors of the prevalence of hookworm infection and strongyloidiasis. In this study would show the infection rates, correlation analysis between environmental risk factors and prevalence of hookworm infection with statistical analysis. We performed a cross-sectional study among 213 participants from rural community of East Kalimantan Province, Indonesia. In this study used two diagnostic methods: Kato Katz and Koga agar plate culture/KAP culture for diagnosing of hookworm and Strongyloides infections. Chi-square analysis was used for study correlation between environmental factors and hookworm infection. Hookworm, strongyloides, and ascaris infections were found in this study; 44.1%, 16.4%, and 7.5% respectively. Environmental risk factors such as; rainy season, quality of soil and infection hookworm and strongyloides in pet have significant correlation (p-value < 0.05) with hookworm infection and strongyloidiasis. The prevalence of hookworm infection and strongyloidiasis has correlation with environmental factors, and the finding in this research could be contributed to decreasing program of hookworm infection and strongyloidiasis especially in rural community area.

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Environmental risk factors of West Nile virus infection of horses in the Senegal River basin

Epidemiology and Infection ◽

10.1017/s095026881000035x ◽

2010 ◽

Vol 138 (11) ◽

pp. 1601-1609 ◽

Cited By ~ 12

Author(s):

V. CHEVALIER ◽

A. DUPRESSOIR ◽

A. TRAN ◽

O. M. DIOP ◽

C. GOTTLAND ◽

...

Keyword(s):

Risk Factors ◽

West Nile Virus ◽

River Basin ◽

Environmental Risk ◽

Environmental Risk Factors ◽

Environmental Data ◽

West Nile ◽

Blood Samples ◽

Senegal River ◽

Senegal River Basin

SUMMARYIn 2005, a serological study was carried out on horses in five ecologically contrasted zones of the Senegal River basin (Senegal) to assess West Nile virus (WNV) transmission and investigate underlying environmental risk factors. In each study zone, horses were randomly selected and blood samples taken. A land-cover map of the five study areas was built using two satellite ETM+ images. Blood samples were screened by ELISA for anti-WNV IgM and IgG and positive samples were confirmed by seroneutralization. Environmental data were analysed using a principal components analysis. The overall IgG seroprevalence rate was 85% (n=367; 95% CI 0·81–0·89). The proximity to sea water, flooded banks and salted mudflats were identified as protective factors. These environmental components are unfavourable to the presence of Culex mosquitoes suggesting that in Senegal, the distribution of the vector species is more limiting for WNV transmission than for the hosts' distribution.

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