**1. Introduction**

The archeological discovery of Schistosoma eggs in a corpse in the Changsha Mawangdui Han tomb in Hunan Province revealed that schistosomiasis has been prevalent in China for over 2000 years. Not until the American physician Logan first reported the clinical diagnosis of schistosomiasis in China [1], did Chinese people begin to consider schistosomiasis as a disease. *Schistosoma*

*japonicum*, one of the five species of schistosome, is widely distributed in China, Indonesia, and The Philippines [2]. As it needs to go through several growth stages in water, the transmission and infection of humans is closely related to specific geographic conditions, which causes difficulties in prevalence control [3]. Schistosomiasis brings a heavy burden to China's population health, social stability, and economic development.

After the establishment of the People's Republic of China in 1949, the central governmen<sup>t</sup> organized and delegated expert teams to conduct a national survey that found 12 provinces and 351 counties where schistosomiasis prevailed [4] with some 10.5–11.8 million people infected. Zedong Mao, the Chinese president back then, with immense political influence, wrote a famous poem "Farewell to the god of plague" and launched a massive country-wide movement to eliminate schistosomiasis [5]. With medical treatment, environmental modification, and molluscicide application, by 1980, four out of the 12 provinces and two thirds of the affected counties successfully repressed the prevalence of schistosomiasis [6]. As for the remaining eight provinces, epidemic areas were mostly distributed in marshlands and mountainous areas with complicated environmental factors that hindered control.

In order to address this predicament and search for a new and effective schistosomiasis control method, Warren and Su conducted a study in Guichi district, Anhui Province, one of the ten historically most severely affected areas in China [7] and confirmed praziquantel therapy could effectively reduce the schistosomiasis prevalence in humans. When combined with snail control in epidemic areas, the prevalence decreased even more significantly. In this study, we performed a 37-years longitudinal study from 1981 to 2017 on the basis of the study conducted by Warren and Su to understand the long-term effects of schistosomiasis transmission control strategies.
