Schistosomiasis in China: an update.

A study tour in China provided information on the current status of schistosomiasis. Although many counties have been cleared of Oncomelania snails, problem areas still exist in the lakes region of the central Yangtze Valley, in hilly or mountainous terrain, and where water level cannot be controlled. In the central Yangtze area the main reservoir of infection is now considered to be cattle. It was estimated that the prevalence of schistosomiasis in 1983 was about 2.4 million cases, mostly light. Considerable effort is being made to develop immunodiagnostic methods to identify the relatively few and often subclinical cases that occur in sparsely endemic areas. Nationwide eradication does not seem feasible at present, necessitating continued surveillance to maintain and consolidate progress and prevent reintroduction of the parasite or its host snails in areas freed from the disease.