Cooperative Fish and Wildlife Research Units Program: Wisconsin Wildlife
Education, Research and Technical Assistance for Managing Our Natural Resources

As part of the Biocomplexity project, researchers have developed a multi-host, single pathogen computer simulation model incorporating important dynamics of the malaria disease cycle in Hawaiian forest ecosystems (Ahumada et al., in review), implemented in a spatially explicit (1 km2) framework. This model is based on a series of ordinary differential equations describing the interactions and demographics among hosts, vectors, and the malaria pathogen. As in many disease models, pathogen dynamics are modeled implicitly by dividing hosts and vectors into susceptible, latent, infectious, and recovered classes. The time step used for model simulations is one day. Although this is a rather short time from the host point of view, it is appropriate for the vectors which have a much shorter life span. Weekly averages of temperature and rainfall are used to drive the vector population and malaria dynamics including larval development and survival rates, gonotropic cycle, and the intrinsic incubation rate for malaria parasites (Ahumada et al., in review). This model framework considers the effects of vector dynamics influenced by altitudinal and climatic drivers and provides the bases for evaluation of more complex multi-host, multi-pathogen models which will facilitate evaluation of pox and pox-malaria infection dynamics, disease transmission, and potential impact on host communities. This project will use computer simulation modeling to evaluate the importance of disease transmission rates, host demographic rates, multiple hosts systems, pathogen characteristics, vector demographic rates, and environmental conditions on the potential dynamics of avian malaria in Hawaiian forest birds. The evaluation will be based on a multi-host (four host species) computer simulation model that has been developed for this disease system. It is projected that this work will require at least 4 months of effort from July 1, 2007 through June 30, 2008. Researchers will conduct computer simulation studies to evaluate the following conservation actions on malaria transmission, vector demographics, and bird demographics at different elevations in Hawaii: 1) management to remove feral pigs and thus reduce mosquito larval sites for 5, 10, and 15 year periods; and 2) the effects of long-term climate change on various components of the disease system