Influence of bovines and rodents in the spread of schistosomiasis across the ricefield-lakescape of Lake Mainit, Philippines: An Optimal Control Study

Schistosomiasis remains a persistent challenge in tropical freshwater ecosystems, necessitating the development of refined control strategies. Bovines, especially water buffaloes, are commonly used in traditional farming practices across rural areas of the Philippines. Bovines, however, are the biggest reservoir hosts for schistosome eggs, which contribute to the active transmission cycle of schistosomiasis in rice fields. We propose a mathematical model to analyze schistosomiasis dynamics in rice fields near the Lake Mainit in the Philippines, an area known for endemic transmission of schistosomiasis, focusing on human, bovine, and snail populations. Rodents, although considered, were not directly included in the control strategies. Grounded in field data, the model, built on a system of nonlinear ordinary differential equations, enabled us to derive the basic reproduction number and assess various intervention strategies. The simulation of optimal control scenarios, incorporating chemotherapy, mollusciciding, and mechanical methods, provides a comparative analysis of their efficacies. The results indicated that the integrated control strategies markedly reduced the prevalence of schistosomiasis. This study provides insights into optimal control strategies that are vital for policymakers to design effective, sustainable schistosomiasis control programs, underscored by the necessity to include bovine populations in treatment regimens.