[Surveillance and risk assessment system of schistosomiasis in Jiangsu Province. I. Distribution of surveillance site and effectiveness of the system].

Objective: To establish the surveillance and risk assessment system of schistosomiasis in Jiangsu Province, so as to provide technical support for timely understanding of the risk of schistosomiasis transmission and implementation of targeted control measures.

Methods: The surveillance sites of schistosomiasis were assigned according to the epidemic status and endemic type of schistosomiasis as well as the characteristics of the water system, and the prevalence of Schistosoma japonicum in humans and domestic animals, and snail status were investigated. In addition, the quality control of serum detection of S. japonicum infections was performed. The prevalence of human and animal S. japonicum infections, snail status and missing diagnosis of serum detection were analyzed and compared among regions.

Results: A total of 27 surveillance sites of schistosomiasis were set up in 26 counties of 10 cities, Jiangsu Province, including 14 sites in transmission-interrupted villages and 13 sites in transmission-controlled villages, and 15 sites in marshland and lake regions, 9 sites in plain regions with water network and 3 sites in mountainous region. In the 27 surveillance sites, a total of 16 617 residents were screened for S. japonicum infection by using dipstick dye immunoassay (DDIA), and 326 were sero-positive, with a sero-prevalence of 1.96% (2.17% for men and 1.8% for women). Of the 326 individuals undergoing parasitological examination, 2 positive cases were detected in the marshland and lake region, with a S. japonicum human prevalence of 0.01%. Of the 762 floating population detected, 10 were positive for blood test, with a sero-prevalence of 1.31%, and no egg-positive individuals were detected. No infection was found in the 476 domestic animals. Of the 746 settings surveyed, a total of 240.7 hm2 snail area was detected, with a mean snail density of 0.06 snails/0.1 m2, and no infected snails were found. There were 780 quality-control sera detected in 26 surveillance sites of schistosomiasis, and the gross coincidence rate was 95.13%, with misdiagnosis rate of 1.28% and missing diagnosis rate of 19.23%.

Conclusion: The surveillance sites of schistosomiasis show reasonable distribution in Jiangsu Province, and the endemic situation of schistosomiasis appears a low level in the whole province.