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Habitat suitability mapping of Anopheles darlingi in the surroundings of the Manso hydropower plant reservoir, Mato Grosso, Central Brazil.

Zeilhofer P, dos Santos ES, Ribeiro AL, Miyazaki RD, dos Santos MA - Int J Health Geogr (2007)

Bottom Line: Vector absence was associated with open vegetation formations such as grasslands and agricultural areas.We suppose that non-significant differences of vector incidences between rainy and dry seasons are associated with the availability of anthropogenic breeding habitat of the reservoir throughout the year.Vector presence is significantly increased in forested areas near reservoirs in bays protected from wind and wave action.

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Affiliation: Department of Geography, Federal University of Mato Grosso, Cuiabá, Brazil. pitalike@terra.com.br

ABSTRACT

Background: Hydropower plants provide more than 78 % of Brazil's electricity generation, but the country's reservoirs are potential new habitats for main vectors of malaria. In a case study in the surroundings of the Manso hydropower plant in Mato Grosso state, Central Brazil, habitat suitability of Anopheles darlingi was studied. Habitat profile was characterized by collecting environmental data. Remote sensing and GIS techniques were applied to extract additional spatial layers of land use, distance maps, and relief characteristics for spatial model building.

Results: Logistic regression analysis and ROC curves indicate significant relationships between the environment and presence of An. darlingi. Probabilities of presence strongly vary as a function of land cover and distance from the lake shoreline. Vector presence was associated with spatial proximity to reservoir and semi-deciduous forests followed by Cerrado woodland. Vector absence was associated with open vegetation formations such as grasslands and agricultural areas. We suppose that non-significant differences of vector incidences between rainy and dry seasons are associated with the availability of anthropogenic breeding habitat of the reservoir throughout the year.

Conclusion: Satellite image classification and multitemporal shoreline simulations through DEM-based GIS-analyses consist in a valuable tool for spatial modeling of A. darlingi habitats in the studied hydropower reservoir area. Vector presence is significantly increased in forested areas near reservoirs in bays protected from wind and wave action. Construction of new reservoirs under the tropical, sub-humid climatic conditions should therefore be accompanied by entomologic studies to predict the risk of malaria epidemics.

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ROC curve of HBR cut-off values of Anopheles darlingi.
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Figure 7: ROC curve of HBR cut-off values of Anopheles darlingi.

Mentions: Figure 7 represents the ROC curve with sensitivity and specificity obtained for LR models with cut-off values of 0.5, 1, 2, 4, 6, 10, 20, and 50. The area under the ROC was found to be 82.51%, considered to be a satisfactory global predictive power [39]. Best equilibrium between sensivity and specificity was obtained for a cut-off value of 6. For final model building, however, we opted for a cut-off value of 4, since positive cases are poorly predicted for cut-off values of 6 and 10.


Habitat suitability mapping of Anopheles darlingi in the surroundings of the Manso hydropower plant reservoir, Mato Grosso, Central Brazil.

Zeilhofer P, dos Santos ES, Ribeiro AL, Miyazaki RD, dos Santos MA - Int J Health Geogr (2007)

ROC curve of HBR cut-off values of Anopheles darlingi.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC1851006&req=5

Figure 7: ROC curve of HBR cut-off values of Anopheles darlingi.
Mentions: Figure 7 represents the ROC curve with sensitivity and specificity obtained for LR models with cut-off values of 0.5, 1, 2, 4, 6, 10, 20, and 50. The area under the ROC was found to be 82.51%, considered to be a satisfactory global predictive power [39]. Best equilibrium between sensivity and specificity was obtained for a cut-off value of 6. For final model building, however, we opted for a cut-off value of 4, since positive cases are poorly predicted for cut-off values of 6 and 10.

Bottom Line: Vector absence was associated with open vegetation formations such as grasslands and agricultural areas.We suppose that non-significant differences of vector incidences between rainy and dry seasons are associated with the availability of anthropogenic breeding habitat of the reservoir throughout the year.Vector presence is significantly increased in forested areas near reservoirs in bays protected from wind and wave action.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Geography, Federal University of Mato Grosso, Cuiabá, Brazil. pitalike@terra.com.br

ABSTRACT

Background: Hydropower plants provide more than 78 % of Brazil's electricity generation, but the country's reservoirs are potential new habitats for main vectors of malaria. In a case study in the surroundings of the Manso hydropower plant in Mato Grosso state, Central Brazil, habitat suitability of Anopheles darlingi was studied. Habitat profile was characterized by collecting environmental data. Remote sensing and GIS techniques were applied to extract additional spatial layers of land use, distance maps, and relief characteristics for spatial model building.

Results: Logistic regression analysis and ROC curves indicate significant relationships between the environment and presence of An. darlingi. Probabilities of presence strongly vary as a function of land cover and distance from the lake shoreline. Vector presence was associated with spatial proximity to reservoir and semi-deciduous forests followed by Cerrado woodland. Vector absence was associated with open vegetation formations such as grasslands and agricultural areas. We suppose that non-significant differences of vector incidences between rainy and dry seasons are associated with the availability of anthropogenic breeding habitat of the reservoir throughout the year.

Conclusion: Satellite image classification and multitemporal shoreline simulations through DEM-based GIS-analyses consist in a valuable tool for spatial modeling of A. darlingi habitats in the studied hydropower reservoir area. Vector presence is significantly increased in forested areas near reservoirs in bays protected from wind and wave action. Construction of new reservoirs under the tropical, sub-humid climatic conditions should therefore be accompanied by entomologic studies to predict the risk of malaria epidemics.

Show MeSH
Related in: MedlinePlus