Spatial pattern of schistosomiasis in Xingzi, Jiangxi Province, China: the effects of environmental factors

Abstract

Background: The recent rebounds of schistosomiasis in the middle and lower reaches of the Yangtze River pose a challenge to the current control strategies. In this study, identification of potential high risk snail habitats was proposed, as an alternative sustainable control strategy, in Xingzi County, China. Parasitological data from standardized surveys were available for 36,208 locals (aged between 6-65 years) from 42 sample villages across the county and used in combination with environmental data to investigate the spatial pattern of schistosomiasis risks.

Methods: Environmental factors measured at village level were examined as possible risk factors by fitting a logistic regression model to schsitosomiasis risk. The approach of ordinary kriging was then used to predict the prevalence of schistosomiasis over the whole county.

Results: Risk analysis indicated that distance to snail habitat and wetland, rainfall, land surface temperature, hours of daylight, and vegetation are significantly associated with infection and the residual spatial pattern of infection showed no spatial correlation. The predictive map illustrated that high risk regions were located close to Beng Lake, Liaohuachi Lake, and Shixia Lake.

Conclusions: Those significant environmental factors can perfectly explain spatial variation in infection and the high risk snail habitats delineated by the predicted map of schistosomiasis risks will help local decision-makers to develop a more sustainable control strategy.

Figure 1

Locations of sampled villages in Xingzi County. Detailed legends: This map shows where the sampled villages are located in the study area.

Figure 2

Predicted prevalence of schistosomiasis in Xingzi County. Detailed legends: This predictive map, over-laid with the observed prevalence in sampled villages, shows the overall prevalence of schistosomiasis over the study area. Beng, Liaohuachi, Shixia, and Poyang denote name of lakes.

Figure 3

Uncertainties of the predictions of schistosomiasis in Xingzi County. Detailed legends: This predictive map, over-laid with the observed prevalence in sampled villages, shows uncertainties of predictions of schistosomiasis over the study area. Beng, Liaohuachi, Shixia, and Poyang denote name of lakes.

Figure 4

Locations of high risk snail habitats in Xingzi County. Detailed legends: The high risk snail habitats are marked with red triangle and Beng, Liaohuachi, Shixia, and Poyang denote name of lakes.