The potential risk and control strategy in low endemic area of schistosomiasis in China.

OBJECTIVE: to describe and analyze the potential risk and suggest the corresponding control strategy in low endemic of schistosomiasis in China.
METHODS: referring the 'national criteria of control and elimination of schistosomiasis' and the 'national criteria of classification of endemic area for chemotherapy'; collecting the data of the re-infection of schistosomiasis in lake region and residual snails in mountain areas and evolution of endemic situation in 'snail ridden areas without schistosomiasis'; analyzing the potential risk in different types of low endemic area and suggesting the control strategies according to the analysis results and historical experiment.
RESULTS: the re-infection rate of schistosomiasis in residents is usually higher in high, medium and low endemic areas in the lake region, once chemotherapy is stopped, the infection rate may rise again to the initial level 2 years later and bovine chemotherapy and snail control in susceptible zone will be selected as the optimal strategies for controlling the endemic situation; the potential risk in mountain areas is the enlargement of snail habitats due to residual snail's reproduction and the control strategy will be to strengthen the surveillance and elimination of residual snails; inputting the infective sources of schistosomiasis is the potential risk in 'snail ridden area without schistosomiasis' and the main control strategy should be put the regular monitoring on the infection sources from hyper-endemic areas and treat the infected domestic animals in time.