Model-based risk assessment for schistosomiasis in a Brazilian context

We develop a stochastic model for Quantitative Risk Assessment for schistosomiasis, i.e., an endemic disease of public concern. The model gives answers in a useful format for public health decisions, uses data and expert opinion, and can be applied to several locations (e. g., South and Central America, the Caribbean, and Africa). It can incorporate many realistic and case-specific features such as: parasite population is stage-structured; periodic praziquantel (PZQ) drug treatment for humans; density dependence; extreme events (prolonged rainfall); site-specific sanitation quality; environmental stochasticity; monthly rainfall variation; uncertainty in parameters; and spatial dynamics. We present preliminary results of a real world application in a Brazilian district. We quantify the risks of disease outbreak, extinction or quasi-extinction under varying scenarios of action plan and compare them against a do-nothing plan. Results give an excellent approximation of the dynamics of the system, in line with literature and field observations.