A Mathematical Model and Optimal Control of Schistosomiasis in Agusan del Sur, Philippines

Schistosomiasis, a parasitic disease caused by extit{Schistosoma japonicum}, is one of the neglected tropical diseases and remains endemic in the Philippines, covering 28 provinces in 12 regions. Unlike other species of extit{Schistosoma}, extit{Schistosoma japonicum} is a zoonotic parasite which infects other mammalian hosts aside from humans. With that nature of the parasite, we construct a mathematical model to study the transmission dynamics of schistosomiasis in Agusan del Sur, Philippines. Here, we consider humans and carabaos as definitive hosts, and snails as intermediate hosts. We conduct stability analysis on the proposed model, and calculate for the basic reproduction number, $R_0$. We also perform sensitivity analysis using the Latin hypercube sampling combined with partial rank correlation coefficient technique to investigate how the number of infected humans is affected by the changes in model parameters. Using the available Philippine schistosomiasis data from the Department of Health, we estimate some model parameters. Finally, we apply optimal control theory to determine optimal strategies to control and prevent the spread of schistosomiasis in the country, which may eventually lead to the elimination of the disease.