From discovery to eradication of schistosomiasis in Japan: 1847-1996

Among the areas in Japan where schistosome infections have occurred for many years, three major areas were Katayama District, Kofu Basin and Chikugo River Basin and three minor areas were Numazu District, Tone River Basin and Obitsu River Bank. The presence of the disease had long been recognised in the Katayama Memoir written by Fujii (1847, in the Chinese Classics). The cause of this endemic disease had been studied by many researchers, and finally a new trematode, Schistosoma japonicum, was discovered by Katsurada in 1904 [Tokyo Iji Shinshi, Vol. 1371, pp. 13-32]. The route of percutaneous infection was proven by Fujinami & Nakamura (1909) [Kyoto Medical Journal, Vol. 6, pp. 224-252] using 17 calves. Miyairi & Suzuki (1913) [Tokyo Iji Shinshi, Vol. 1836, pp. 1961-1965] determined a small snail, Oncomelania nosophora, as being the intermediate host, and clarified the development of the schistosome in the snail. To kill schistosome eggs, human faecal matter ('night soil') was stored for 2 weeks or more before using as fertiliser. Control of the parasite used caustic lime and calcium cyanamide to kill eggs, cercariae and Oncomelania snails. Susceptible cows were replaced with horses, which were more resistant to infection as the animal of burden for agriculture. Ditches around the rice fields were cemented for destruction of snail habitats. For snail control, sodium pentachlorophenate (NaPCP) was sprayed extensively. Some wetlands were drained and reclaimed and in selected localities, the river bottom was dredged. Such projects were undertaken with government support and aided by community participation. Epidemiological surveys began in 1910, first at Kofu, and infected people were treated with sodium tartar emetic (Stibnal) after 1921. The total number of cases detected in Japan in 1920 was about 8000. This figure was reduced annually down to 438 by 1970. The last human case of new infection found in Japan was at Kofu in 1977. Although snails were eradicated in most areas by 1983, a limited number of uninfected snails remain at Kofu and Obitsu.