Current situation of Oncomelania sanilas, the intermediate host of Schistosoma japonicum, in China

Abstract

Schistosoma japonicum is currently endemic in Asian countries, especially China and the Philippines. Endemic foci in China are located in two cities and 7 provinces along the Yangze river and known to still be actively endemic. The intermediate snail hosts Oncomelania hupensis hupensis and O. h. robertosoni are both subspecies of snails distributed in Japan. From the viewpoint of disease control, the Chinese situations are much more difficult than those in Japan, because of environmental factors observed with seasonal changes in water levels of the Yangze river. Endemic foci in China are divided into three types according to the geographical areas, namely marshland type, water canal type and hHilly type. In each endemic focus, countermeasures should be planned considering the vegetation, soil content and agricultural environment. The Chinese government decided to implement nation-wide activities aimed to eradicate schisotosomiasis no later than 2020. For this purpose, comprehensive control activities are being strategically carried out. Those activities must be monitored to determine whether the outcomes are successful. Together with those activities, new tools for disease control are being intensively introduced in endemic areas of China. In his review, currently implemented control activities in China are described and future prospects of the disease endemicity is discussed.