Historical view of schistosomiasis japonica in Japan: implementation and evaluation of disease-control strategies in Yamanashi Prefecture

We summarized historical aspects of disease control activities targeting schistosomiasis japonica in Kofu basin, Yamanashi Prefecture, Japan. Kofu Basin was one of the biggest endemic foci of schistosomiasis japonica in Japan, and the last place where transmission of Schistosoma japonicum was confirmed in Japan. Because of the most severe endemic situations in Yamanashi, intensive control measures had been implemented by the central as well as the local government. The last human case in Japan was in 1977, which is just before praziquantel being available. Therefore, the main efforts were focused on snail control. Mass examination and mass chemotherapy were implemented, however, the compliance was not so good because of the severe side effects due to the available therapeutics, Stibnal. Along with socioeconomic development after World War II, big changes in land use, life style, and farming led drastic reduction in the disease prevalence in Kofu Basin in the 1960s. A large amount of budget was also used for disease control. Cementing water canals covered more than 95% of paddy fields in Kofu Basin, and this resulted in ecological changes. After elimination of schistosomiasis, environmental repair is the urgent subject in Kofu Basin. Our experiences in Yamanashi contain both good influences and also a lot of reflection. It is important to evaluate each activity in our history before we give intensive cooperation with countries where endemic foci is still present.