Testing the importance of ecological theory in predicting human disease: Does avian diversity and community structure predict the incidence of human West Nile virus infection?

• John P. Swaddle

Abstract
West Nile virus affects bird and mammal populations worldwide and is recognized as an emerging disease of substantial public health, veterinary, and conservation concern. The virus primarily infects and replicates in birds but also affects “unintended” hosts, such as humans, when local bird communities have high levels of infection. Some bird species are much more likely to harbor the virus than others, and ecological theory predicts that the structure of local bird communities affects the amount of virus in the area and the chances of humans contracting the disease. In particular, as the diversity of local bird populations increases, the disease should be diluted among less-competent hosts and human disease incidence is predicted to decrease. Therefore, in areas with greater avian diversity, human incidence of West Nile should be lower. I will test this ecological prediction by comparing incidence of human West Nile infection with measures of avian community structure and diversity across the Eastern and Central US states from 2002-05. My own pilot data support these predictions and suggest that the completed project can be used to better predict the risk of West Nile to humans and can inform the design of more effective public health initiatives.