High NDVI |
% of area in squares with high density of green vegetation |
Greater density of vegetation is associated with presence of vectors for VL and higher incidence of human VL 22. Lainson R, Rangel EF. Lutzomyia longipalpis and the eco-epidemiology of American visceral leishmaniasis, with particular reference to Brazil: a review. Mem Inst Oswaldo Cruz 2005; 100:811-27.,1818. Cerbino Neto J, Werneck GL, Costa CHN. Factors associated with the incidence of urban visceral leishmaniasis: an ecological study in Teresina, Piauí State, Brazil. Cad Saúde Pública 2009; 25:1543-51.,1919. Werneck GL, Costa CHN, Walker AM, David JR, Wand M, Maguire JH. Multilevel modelling of the incidence of visceral leishmaniasis in Teresina, Brazil. Epidemiol Infect 2007; 135:195-201.
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Medium NDVI |
% of area in squares with medium density of green vegetation |
Low NDVI |
% of area in squares with low density of green vegetation |
Bare soil |
% of area in squares with bare soil |
Bare soil in a city undergoing expansion, like Teresina, represents intermediate-stage urbanization: environmental destruction for subsequent occupation with large housing projects on the city’s periphery. Described as an element of the landscape associated with increased incidence of human VL 1616. Almeida AS, Werneck GL, Resendes APC. Classificação orientada a objeto de imagens de sensoriamento remoto em estudos epidemiológicos sobre leishmaniose visceral em área urbana. Cad Saúde Pública 2014; 30:1639-53.
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High DU 1 |
% of area in squares covered by residential structures with little vegetation |
Urbanization process has been associated with increased incidence of VL due to the high adaptability of the principal vector, Lutzomyia longipalpis, to peridomiciliary conditions, exploiting the accumulated organic matter generated by domestic animals and poor sanitation 22. Lainson R, Rangel EF. Lutzomyia longipalpis and the eco-epidemiology of American visceral leishmaniasis, with particular reference to Brazil: a review. Mem Inst Oswaldo Cruz 2005; 100:811-27.,44. Rangel EF, Vilela ML. Lutzomyia longipalpis (Diptera, Psychodidae, Phlebotominae) and urbanization of visceral leishmaniasis in Brazil. Cad Saúde Pública 2008; 24:2948-52.,1818. Cerbino Neto J, Werneck GL, Costa CHN. Factors associated with the incidence of urban visceral leishmaniasis: an ecological study in Teresina, Piauí State, Brazil. Cad Saúde Pública 2009; 25:1543-51.
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High DU 2 |
% of area in squares covered by residential structures with extensive vegetation |
Green urban |
% of area in squares covered by sparse residential structures with extensive vegetation |
Abundant vegetation close to households represents typical environment for transmission of VL, intersecting the sylvatic and peridomiciliary transmission cycles 1717. Harhay MO, Olliaro PL, Costa DL, Costa CH. Urban parasitology: visceral leishmaniasis in Brazil. Trends Parasitol 2011; 27:403-9.
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Water |
% of area in squares covered by water |
Not used in the analyses, since water bodies are not a preferential habitat for sand flies 22. Lainson R, Rangel EF. Lutzomyia longipalpis and the eco-epidemiology of American visceral leishmaniasis, with particular reference to Brazil: a review. Mem Inst Oswaldo Cruz 2005; 100:811-27.
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