Correlation between climate data and land altitude for Fasciola hepatica infection in cattle in Santa Catarina, Brazil / Correlação entre clima e altitude para determinar a infecção de Fasciola hepatica em bovinos em Santa Catarina, Brasil

Abstract Fascioliasis is a food-borne parasitic disease that affects a range of animals, including humans caused by Fasciola hepatica. The present study aimed to determine the spatial distribution of bovine fasciolosis and to assess the correlation between the high Positivity Index (PI) and climate data and land altitude, from 2004 to 2008 and 2010 in Santa Catarina (SC), Brazil. Condemned livers of slaughtered animals were obtained from 198 out of 293 municipalities and from 518.635 animals, exclusively from SC. There was a statistically significant difference (P < 0.001) between the prevalence of F. hepatica and land altitude ( ρ ^ s = -0.43). The highest PI (above 10.1%) was observed in cities at 500 to 600 m (P < 0.01; ρ ^ s = -0.47) of altitude. There was no correlation between fascioliasis and rainfall in SC. It was determined that weather conditions in the past decade did not impose any limitation to the occurrence of the parasite, making it a disease of permanent clinical importance. These findings are essential to regions with similar geographical and climate conditions (i.e. altitude), when considering long-term control measurements, where animals and humans can be infected.

Resumo A fasciolose é uma doença parasitária que afeta uma gama de animais, incluindo humanos, causada por Fasciola hepatica no Brasil. Este estudo teve o objetivo de determinar a distribuição espacial da fasciolose e conferir a correlação do alto índice de positividade (PI), com os dados de clima e altitude, entre 2004 a 2008 e 2010 em Santa Catarina (SC), Brasil. Foram obtidos fígados em frigoríficos de SC, de 518.635 animais de 198 municípios, de um total de 293. Houve diferença estatística significativa (P < 0,001) entre a prevalência de F. hepatica e a altitude ( ρ ^ s = -0,43). O maior PI (acima de 10,1%) foi observado em municípios de 500 a 600 m (P < 0,01; ρ ^ s = -0,47) de altitude. Não foi observada correlação entre fígados parasitados e pluviosidade em SC. Foi observado que os dados climáticos na ultima década não apresentaram limitação para a ocorrência do parasito, fazendo com que o desafio clinico da infecção tenha sido permanente. Os dados são importantes para locais com condições geográficas e climáticas semelhantes (ex. altitude), para considerar medidas de controle a longo prazo, nas quais animais e humanos poderão ser infectados.

A geoprocessing approach for studying and controlling schistosomiasis in the state of Minas Gerais, Brazil

Geographical information systems (GIS) are tools that have been recently tested for improving our understanding of the spatial distribution of disease. The objective of this paper was to further develop the GIS technology to model and control schistosomiasis using environmental, social, biological and remote-sensing variables. A final regression model (R² = 0.39) was established, after a variable selection phase, with a set of spatial variables including the presence or absence of Biomphalaria glabrata, winter enhanced vegetation index, summer minimum temperature and percentage of houses with water coming from a spring or well. A regional model was also developed by splitting the state of Minas Gerais (MG) into four regions and establishing a linear regression model for each of the four regions: 1 (R² = 0.97), 2 (R² = 0.60), 3 (R² = 0.63) and 4 (R² = 0.76). Based on these models, a schistosomiasis risk map was built for MG. In this paper, geostatistics was also used to make inferences about the presence of Biomphalaria spp. The result was a map of species and risk areas. The obtained risk map permits the association of uncertainties, which can be used to qualify the inferences and it can be thought of as an auxiliary tool for public health strategies.