Endemic situation of schistosomiasis in national surveillance sites of Zhenjiang City from 2015 to 2019

OBJECTIVE To analyze and investigate the changing trend of the endemic situation of schistosomiasis in national surveillance sites of Jiangsu Province from 2011 to 2018, so as to provide scientific evidence for formulating strategies for schistosomiasis control. METHODS From 2011 to 2014, the national schistosomiasis surveillance sites were set in seven schistosomiasis endemic counties (cities, districts) across Jiangsu Province as according to the National Schistosomiasis Surveillance Scheme (2011 version), and from 2015 to 2018, the national surveillance sites were assigned in all 64 counties (cities, districts) endemic for schistosomiasis in Jiangsu Province according to the National Schistosomiasis Surveillance Scheme (2014 version). Schistosoma japonicum infections in local populations, mobile populations and livestock, and snail status were monitored in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and the monitoring data were statistically analyzed. RESULTS The sero-prevalence of S. japonicum infections was 1.50% to 4.61% among local populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and a higher sero-prevalence was seen in men than in women, with the sero-positives predominantly detected in local populations at ages of over 50 years. The positive rate of stool examinations was 0 to 0.14% among sero-positive local populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no acute case was found in local populations during the study period. The sero-prevalence of S. japonicum infections was 0.46% to 15.97% among mobile populations in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no egg-positives were identified. A total of 1 453 livestock were tested in the national schistosomiasis surveillance sites of Jiangsu Province from 2011 to 2018, and no S. japonicum infections were detected. During the period from 2011 through 2018, snail survey was conducted in an area of 216 million m2 in the national schistosomiasis surveillance sites of Jiangsu Province, and 1 291.01 hm2 snail habitats were identified, with snail densities ranging from 0.01 to 0.47 snails/0.1 m2; however, no S. japonicum infections were identified in snails. CONCLUSIONS The overall endemic situation of schistosomiasis appears a tendency towards a decline in Jiangsu Province, and S. japonicum infection remains at a low level in both humans and livestock. No S. japonicum infection has been identified in local populations in Jiangsu Province since 2012. In the future, monitoring and management of imported sources of S. japonicum infections should be intensified in Jiangsu Province, and the capability building of passive surveillance of schistosomiasis should be improved in sentinel hospitals in national schistosomiasis surveillance sites of Jiangsu Province. In addition, the examination of schistosomiasis should be strengthened in mobile populations in Jiangsu Province, a sensitive and effective surveillance-response system for schistosomiasis is urgently needed.