[Surveillance of schistosomiasis in Sichuan Province, 2005-2010].

OBJECTIVE: To understand the epidemic trend of schistosomiasis in Sichuan Province so as to provide the evidence for formulating schistosomiasis control strategy. METHODS: According to the National Schistosomiasis Surveillance Protocol, the national surveillance sites in Sichuan Province were selected. The schistosomiasis surveillance was carried out continuously from 2005 to 2010. RESULTS: Nine national schistosomiasis surveillance sites were established in Pujiang, Guanghan, Zhongjiang, Fucheng, Dongpo, Danling, Renshou, Xichang and Dechang counties. The Oncomelania hupensis snail area decreased from 351 853 m2 in 2005 to 128 285 m2 in 2010, the snail density from 0.70 to 0.21 per 0.1 m2, the snail infection rate from 0.06% to 0, the positive rate of human serum schistosome antibody from 19.41% to 7.62%, the schistosome infection rate of human population from 1.93% to 0.10%, and the infection rate of livestock from 4.50% to 1.02%. The snails were found mainly in ditch, rice field and other moist field. CONCLUSIONS: Though the endemic of schistosomiasis has reached a low level in Sichuan Province, the endemic situation fluctuates at a narrow range in some surveillance sites. Therefore, the surveillance work should be carried out continuously.

[Study on the re-emerging situation of schistosomiasis epidemics in areas already under control and interruption].

OBJECTIVE: To study the current situation and the cause of schistosomiasis resurgence in order to provide reference for formulation of control strategy. METHODS: Data in 1999 - 2003 and baseline data in some areas were collected and analyzed retrospectively. RESULTS: Resurgence was seen in 6.15% (16/260) of the areas and one farm where transmission of schistosomiasis had been interrupted and 33.33% (21/64) of the areas already under control. Snails appeared to have been rebounded only in six counties (farm) while in thirty two counties that rebound was seen in both snails and disease prevalence. Tendency of increase in the total numbers of patients, acute patients and cattle with schistosomiasis, areas with snails were seen from 1999 to 2003. CONCLUSIONS: Environmental, ecological, societal factors such as flood, acequia, lack of expenditure and lack of incentives at work etc. contributed to the resurgence of epidemics in those areas that criteria had been reached. Surveillance and supervision on the sources of infection and snail diffusion, especially in the areas where the transmission of schistosomiasis had already been under control.