[Potential risks for transmission of schistosomiasis caused by mobile population in Shanghai].

Objective: To understand the potential risk for schistosomiasis transmission caused by introduction of infection source from mobile population in Shanghai.

Methods: Field investigation was conducted in the suburb of Shanghai City by screening the mobile population living in Shanghai for more than 1 month and over 1 years old in a procedure of interviewing, serum indirect hemagglutination (IHA) test, and then fecal examination to detect the eggs with nylon sedimentation approach for those IHA positives.

Results: Among 2,931 mobile people investigated, 1,575 were male (53.74%) and 1356 were female(46.26%); 138 out of 2931 were positive in IHA test (4.71%). 1938 (66.12%) out of 2 931 came from Schistosoma japonicum-endemic provinces and its positive rate in mobile population (5.99%) was significantly higher than those from the transmission-interrupted provinces (2.6%) (chi2=10.28, P<0.01), and those from non-endemic provinces (1.68%) (chi2=12.86, P<0.01). The 138 IHA positives all showed negative in fecal examination. In accordance with the serum positive rate and egg-infection rate in the national reporting system in 2004, it was estimated that there would be about 13 356 and 1 699 potential serum positive cases respectively from endemic area and transmission controlled area, and about 2,168 and 255 egg-positive cases from the two kind areas respectively, majority of the cases were from Anhui Province.

Conclusion: Schistosomiasis transmission risks potentially exist in Shanghai suburb due to the introduction of infected mobile people from other endemic provinces, and a surveillance system and quick response are needed for the possible re-emergence of the disease.