EMERGING AND REEMERGING HELMINTHIASES AND THE PUBLIC-HEALTH OF CHINA

Despite great strides in their control throughout the People's Republi c of China, helminth infections remain an important public health prob lem. The Institute of Parasitic Diseases of the Chinese Academy of Pre ventive Medicine, under the guidance of the Chinese Ministry of Health , completed a nationwide survey of more than 1 million people that sho wed the high prevalence and intensity of intestinal nematode infection s; prevalence can sometimes exceed 50% in the Yangtze River valley pro vinces. Schistosoma japonicum is also a major cause of illness in this region. Attempts to control Chinese helminthic diseases with conventi onal anthelminthic drugs have been partially thwarted by high posttrea tment rates of reinfection. Recently, several new human trematode path ogens have been identified. Novel approaches to chemoprophylaxis and v accination may alleviate the public health problem caused by Chinese h elminths. However, recombinant helminth vaccine development will depen d on first cataloguing the extensive genetic diversity of Chinese helm inths and candidate vaccine antigens. Evidence from biogeography, gene tics, and systematics suggests that the genetic diversification of Chi nese helminths and their vectors is an ongoing evolutionary process th at began 12 million years ago near the convergence of major Asian rive r systems. Construction of the Three Gorges Super Dam on the Yangtze R iver may promote the emergence and reemergence of new helminths and th eir snail vectors.