Feng, Milner, Minchella The interactions between parasitic trematodes and their invertebrate and vertebrate hosts are complex. Models of these interacting systems are similarly complex in order to capture biologically relevant features of the systems. Advances for many questions in this area face difficulties in part because of the large number of parameters involved in the models and because of the limited data available. The investigators combine the theoretical and empirical experience of a parasitologist and the modeling and theoretical expertise of mathematicians to develop and investigate these models. The work of this project is threefold: first, new models are proposed for host-parasite interactions, with more complex models motivated by biological considerations and newly available data; second, a study of some mathematical properties of each model is carried out and their biological and ecological implications assessed, such as parasite population control or potential species extinction; third, validation of the models through comparison of model results with field data follows. The goal of the project is to develop a theoretical framework for the study of questions associated with host-parasite interactions. A particular host-parasite system is used, human-schistosome-snail (macroparasitic disease), to highlight the generality of our approach. Specific objectives are to develop mathematical models to understand the role of various components of host-parasite interactions in the disease transmission dynamics, to determine which biological details are critical components in the model, to construct and analyze appropriate models in which the parameters are readily related to field data, and to provide useful information for field workers and policy makers in public health. The project significantly advances our knowledge and understanding of the dynamics of host-parasite systems that include intermediate hosts, by providing usable models to study natural systems, by analyzing their sensitivity to the parameters affecting the dynamics, and by allowing structuring of the complexities of the systems into hierarchies. Just as important is the possibility to help address some of the theoretical issues in the control of schistosomiasis via chemotherapy.
