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Top1. Introduction
The World Health Organization (WHO) emphasizes the importance of control of Neglected Tropical Diseases (NTDs). Among NTDs, schistosomiasis is reported to be found in at least 78 countries, most of which are developing countries and 258 million people in total required preventive treatment for schistosomiasis in 2014 (WHO 2016). In the past, Japan had endemic areas of schistosomiasis but it was eradicated 100 years after the discovery of the parasite, Schistosoma japonicum. Of the endemic areas in Japan, the Chikugo river basin in Saga and Fukuoka prefectures in Kyûshû saw measures where local people, their community and the local and national governments were all involved in eradicating the disease (Tsutsumi 2005). No patient has been reported since 1980 when two final patients were found (Tsutsumi 1986).
Schistosomiasis has an impact not only on individuals but also on society. For individuals, infection with Schistosoma japonicum, currently seen in China and Philippines, brings high fever and bloody mucous stool in the acute phase and liver cirrhosis and ascites in the chronic phase, which can lead to death. If the eggs get clogged in cerebral blood vessels, neurological symptoms such as epileptic seizures occur. Both S. mekongi distributed in Laos and Cambodia and S. mansoni in Africa and other areas cause symptoms similar to S. japonicum. The symptom of Schistosoma haematobium in Africa and the Middle East is hematuria and often includes bladder cancer as a complication (Uchida et al. 2005).
For society, as schistosomiasis passes into the chronic phase like other parasite infection, it hinders child development and also it decreases the work force when adults are infected (Aoki 2007). The current main stream of countermeasures for schistosomiasis is the large-scale treatment called Preventive Chemotherapy (WHO 2016). Oral administration drugs are distributed in a means of Mass Drug Administration (MDA), which works also as a prevention to transmission (Ichimori 2013). However, other preventive measures are also necessary as those who recover frequently get infected again (Ohmae et al. 2004, Nakamura 2007).
Accordingly, if possible introducing measures in parallel with MDA in the current endemic areas in developing countries can be presented, using the successful case of the Chikugo river basin as a model, future control measures of schistosomiasis could be more effective. However, it is difficult to adapt Japanese measures to developing countries where environmental and financial situations differ. Particularly, the core of the control methods in the Chikugo river basin was eradication of the intermediate host snail, Oncomelania nosophorai by mostly cementing riverside areas and ditches, usage of molluscicides, and environmental modifications, which involved huge cost. This method is difficult in developing countries where funds and resource are not adequately ensured. Furthermore, Matsuda and Kirinoki (2005) write that the effect of usage of molluscicides and their influence on the environment need to be carefully considered in the endemic areas of Schistosoma mekongi as the intermediate snail host lives in large rivers which local people also use in their daily lives. In addition, it is hard to avoid thinking of the fact that it is realistically unfeasible to eradicate the intermediate snail host in the vast basin. In other words, it is estimated to be extremely difficult to implement measures for eradication of the intermediate host taken in the Chikugo river basin from both financial and environmental aspects.
Considering these, control measures in the Chikugo river basin were closely researched to find applicable methods. Consequently, knowledge and awareness-raising activities for prevention (Saga 1991) and active community participation in the control measures (Tosu City 2009) were confirmed.
Regarding the knowledge of the disease among local people in currently developing countries, Nakamura (2007) performed a recognition survey in the endemic areas of Schistosoma mekongi in Lao on local school children, the highest risk group and the most active transmitters. As a result, more than 70% were found out to be unaware of schistosomiasis. He writes that effective health education needs to be expanded urgently. This result implies that knowledge of the disease is not widespread in endemic areas in developing countries.