BACKGROUND: Poyang Lake, the largest fresh water lake in China, is the major transmission site of Schistosoma japonicum in China. Epidemics of schistosomiasis japonica have threatened the health of residents and stunted social-economic development there. OBJECTIVE: This article aims at evaluating the effect of various control measures against schistosomiasis: selective mass treatment (ST), targeted mass treatment (TT), mass treatment for animal reservoirs (MT), and health education (HE), on reduction of the prevalence through simulations based on a mathematical model. METHODS: We proposed a mathematical model, which is a system of ordinary differential equations for the transmission of S. japonicum among humans, bovines, and snails. The model takes into account the seasonal variation of the water level of Poyang Lake that is caused by the backflow of the Yangtze River and inflow from five small rivers, which influences the transmission of S. japonicum. For the purpose of dealing with the age-specific prevalence and intensity of infection, the human population was classified into four age categories in the model. We carried out several simulations resulting from the execution of ST and TT for elementary school children (E Sch), and combinations of ST, MT, and HE. RESULTS: The simulations indicated that all of the control measures only for humans had a trend of revival after interruption, and a combination of ST and MT has a significant effect on reducing human infection. Although TT and HE had a significant effect on the prevalence in the E Sch group, it had little effect on the overall human population. CONCLUSION: The simulations indicate that measures targeted to bovines such as chemotherapy besides humans will be vital to eliminate the transmission of S. japonicum in the Poyang Lake region. Moreover, it is desirable to improve health education for fishermen and herdsmen.
BACKGROUND: Poyang Lake, the largest fresh water lake in China, is the major transmission site of Schistosoma japonicum in China. Epidemics of schistosomiasis japonica have threatened the health of residents and stunted social-economic development there. OBJECTIVE: This article aims at evaluating the effect of various control measures against schistosomiasis: selective mass treatment (ST), targeted mass treatment (TT), mass treatment for animal reservoirs (MT), and health education (HE), on reduction of the prevalence through simulations based on a mathematical model. METHODS: We proposed a mathematical model, which is a system of ordinary differential equations for the transmission of S. japonicum among humans, bovines, and snails. The model takes into account the seasonal variation of the water level of Poyang Lake that is caused by the backflow of the Yangtze River and inflow from five small rivers, which influences the transmission of S. japonicum. For the purpose of dealing with the age-specific prevalence and intensity of infection, the human population was classified into four age categories in the model. We carried out several simulations resulting from the execution of ST and TT for elementary school children (E Sch), and combinations of ST, MT, and HE. RESULTS: The simulations indicated that all of the control measures only for humans had a trend of revival after interruption, and a combination of ST and MT has a significant effect on reducing humaninfection. Although TT and HE had a significant effect on the prevalence in the E Sch group, it had little effect on the overall human population. CONCLUSION: The simulations indicate that measures targeted to bovines such as chemotherapy besides humans will be vital to eliminate the transmission of S. japonicum in the Poyang Lake region. Moreover, it is desirable to improve health education for fishermen and herdsmen.