Evaluation of schistosomiasis surveillance after blocking of its transmission in Jiaxing, Zhejiang, 1995-2012

Objective To evaluate the schistosomiasis surveillance after its transmission was blocked in Jiaxing and provide scientific evidence for the future prevention and control strategy. Methods Different kinds of snail survey were conducted every year by using mechanic-environmental screening method in previous epidemic areas; monitoring points were also set to capture floater, ships from other places were checked for any possible snail importation; potential patients, including the residents in previous epidemic areas,imported and suspected cases were examined by using indirect hemagglutination test, circumoval precipitin test and enzyme linked immunosorbentassay. Stool examination was conducted for the positive people. Results Totally 417 snail blocks were found in 67 villages in 5 counties, covering an area of 793.2 km2, no infection was found in 781 649 randomly captured snails. Among 989 783 serum samples from suspected patients, 22 089 were positive. Four imported patients were found by stool examination, and no local cases was found. Conclusion Schistosomiasis was under control in the past 18 years, but snails and imported cases still exist, which is the potential factor for re-transmission. The future surveillance emphasis should be put on the previous epidemic areas, especially those where snails till existed in the past 20 years and even after urbanization. The surveillance should be strengthened in people who often visit epidemic area.