Epidemiological features and control strategies of schistosomiasis japonica in China.

Schistosomiasis japonica in China has a long history and wide distribution. In the last three decades, great achievements have been obtained in schistosomiasis control. Among 12 formerly endemic provinces, municipalities, and autonomous regions, transmission has been successfully controlled in 2 provinces, 1 municipality and 1 autonomous region. Among 380 formerly endemic counties, transmission has been interrupted in 158 and is under control in 101. Most remaining endemic areas are located in marshlands, lake and mountainous regions. By the ecological and epidemiological features, the endemic areas in lake and mountainous regions can be classified into different categories. Infection is related to exposure to infected lake and ditch water. The inhabitant activities and level of education have much to do with the frequency of water contact. The density of the infected snail is the main index of determining the high-risk place in the mountain and lake regions, and livestock such as buffalo and pigs, the principal reservoir in the endemic areas. Properly arranged annual chemotherapy with praziquantel can reduce the prevalence rate of inhabitants and livestock. However, the prevalence rate can climb again rapidly. Therefore, a maintenance phase is urgently needed. Modification of the snail-ridden environment should be linked with agricultural development and construction of water conservancy. Surveillance should be strengthened in the area where schistosomiasis has been controlled.