Spatial-temporal variations of Schistosoma japonicum distribution after an integrated national control strategy: a cohort in a marshland area of China.

BACKGROUND: Schistosomiasis transmission is typically focal. Understanding spatial variations of Schistosoma infections and their associated factors is important to help to invent site-specific intervention strategies. METHODS: A five-year longitudinal study was carried out prospectively in 12 natural villages, Guichi district of Anhui province. A GIS-based spatial analysis was conducted to identify geographic distribution patterns of schistosomiasis infections at the household scale. RESULTS: The results of the spatial autocorrelation analysis for 2005 showed that there were significant spatial clusters of human infections at the household level, and these results were in agreement with that of the spatial scan statistic. As prevalence of infections in humans decreased over the course of control, the spatial distribution of these infections became less heterogeneous. CONCLUSIONS: The findings imply that it may be necessary to re-assess risk factors of S. japonicum transmission over the course of control and to adjust accordingly control measures in the communities.

[Investigation on prevalent trends and analysis of control period among floating population in schistosomiasis endemic areas of Guichi District].

OBJECTIVE: To understand the characteristics of the floating population infected with Schistosoma japonicum, so as to provide the evidence for constituting and optimizing control strategy. METHODS: By the cluster random sampling method, six highly endemic villages from the different endemic types in Guichi District were selected as the research areas . The basic information and infected status of the floating population were surveyed by questionnaires and examination between 2000 and 2009. RESULTS: The time when the floating population returned to their homes mainly focused on Spring Festival between 2000 and 2009, and more than 83% of people returned. The infection rate of the floating population was similar to or more than that of the local residents. During the ten years, the reduction of the infection rates in the floating populations (from 5.29% to 2.63%) was consistent with the reduction of the infection rates in the local residents (from 5.28% to 2.68%). However, the reduction of the infection rates in the floating population who worked in the non-endemic areas was more than that in the local residents. CONCLUSION: Spring Festival is the optimal time for detecting and treating schistosomiasis in the floating population.