Investigating social and environmental predictors of human cases of West Nile Virus

Since its appearance in the United States in 1999 there have been 19,706 cases of West Nile Virus (WNV) which have resulted in 845 deaths according to reports by the CDC through the year 2005. Because of its potential to cause devastating illness and the lack of a specific treatment, further studies are warranted to better inform efforts targeted at prevention and control. In the state of Tennessee, over half of the cases of WNV have occurred in Shelby County. This study uses geographic information systems and statistical methods to investigate whether or not various environmental and socioeconomic factors are important predictors of human cases of WNV disease in Shelby County, Tennessee. Information about the geographic location of cases in Shelby County from the years 2002 through 2004, as well as the location of mosquito traps and the results of testing for infected mosquitoes were obtained from the Memphis and Shelby County Health Department. Socioeconomic and environmental factors including age of the population, race, income, age of housing, presence of vacant housing, and presence of water were obtained from the United States 2000 Census. Preliminary results show that, of the variables considered, the age of housing has the strongest association with the occurrence of WNV cases in Shelby County. Age of the population and the presence of vacant housing also appear to be important factors. This presentation will discuss the findings from this study and implications for targeted prevention and control efforts.