Progress and problems in schistosomiasis control in China.

In China, schistosomiasis control has been given a high priority in public health for more than 30 years. Among 372 counties formerly endemic for S. japonicum, transmission has been interrupted in 125 counties and in 141 counties it is under effective control. The numbers of infected persons and infected cattle were estimated to be 10 million and 1.2 million respectively in the 1950s compared with recent estimates of 870,000 (1987) and 100,000 (1986) respectively. Oncomelania snail habitats were reduced from more than 14 billion square metres in 1950s to 3.2 billion square metres in 1987. However, the endemic areas left, mainly in lake and mountainous regions, present greater difficulties and to bring them under control is a long-term task.