*Infection in Humans*

The trend of schistosomiasis infection rates in the residents of Sanlian and Guifan villages over the last 37 years was shown in Figure 2. In 1981, the prevalence of schistosomiasis was 32.81% in Sanlian village and 30.00% in Guifan village ( *χ*2 = 1.839, *p* = 0.175). With the intervention measures of human chemotherapy and snail control in Sanlian village, the prevalence dropped to 2.66% in 1984, while in Guifan village with chemotherapy only, the prevalence was only reduced to 11.25% ( *χ*2 = 41.576, *p* = 0). By 1987, the prevalence in Guifan village increased to 21.25%, while the rate in Sanlian village rose to 20.78% until 1989. Since 1987, the local governmen<sup>t</sup> in Guifan village has strengthened its control work so the rate declined again. Since the implementation of WBLP in 1992, the prevalence in Sanlian and Guifan villages had continued to decrease from 12.51% and 14.10% in 1992 to 3.29% and 2.89% in 1994. There was a volatile stage, with no obvious change trend in both villages from 1995 to 2004. In 1998 and 1999, infection rates in Sanlian and Guifan reached their respective peaks. A comprehensive control strategy has been implemented since 2005, and the prevalence decreased from 8.12% in 2005 to 0 in 2014 in Sanlian and from 14.39% to 0.70% for the same period in Guifan. There was no infected person detected in either village from 2015 to 2017. Both prevalences had significant downtrends since 2005 (Sanlian *χ*2 = 7.995, *p* = 0.005; Guifan *χ*2 = 9.433, *p* = 0.002).

**Figure 2.** Prevalence of *Schistosoma japonicum* infection in humans in two villages during 1981–2017. (1) The adjusted prevalence formula: *p*' = *P*0+β−1 *<sup>α</sup>*+β−1 *p*: Adjusted prevalence; *p0*: Observed prevalence; α: Sensitivity; β: Specificity [10]; (2) The Kato-Katz (KK) 2 slides method was used in 1981–1994: α = 0.64, β =1[11]; The indirect hemagglutination assay (IHA) method was used in 1995–2004, but IHA not meet the condition of adjusted formula [10]; The Kato-Katz 3 slides method was used in 2005–2017, α = 0.75, β =1[11]; (3) Prevalence were assessed after the transmission season for each year in Sanlian and Guifan villages. (4) The I bars represent 95% confidence intervals.
