As a result of the schistosomiasis control program since 1995, disease prevalence has been dramatically decreasing in the endemic areas in Cambodia (Sinuon et al., 2007^***). Since the decrease in prevalence results in a reduction of worm burden in patients, the difficulty of detecting eggs in feces is increasing. As described in this report, our seroepidemiological survey indicates the existence of a risk of contact with schistosomes in villages in Kratie province. The mass drug administration campaign intercepts the transmission of schistosomiasis from humans to snails and has been very effective in reducing the incidence of schistosomiasis mekongi. In areas where the risk of schistosome infection remains, more studies on reservoir hosts and the intermediate host snail are necessary for further progress toward the elimination of the disease. Determining the distribution of the intermediate host snails is important for the control of schistosomiasis mekongi. We know that their habitat may change due to a variety of factors. For example, the strength of the water current, direction of the stream, landscape, and distribution of stones along riverbanks can affect the distribution of N. aperta. Therefore, repeated snail surveys may be required to determine infection sites in endemic villages such as Kbal Chuor.