Predicting West Nile Virus Infection Risk From the Synergistic Effects of Rainfall and Temperature.

Mosquito-based surveillance is a practical way to estimate the risk of transmission of West Nile virus (WNV) to people. Variations in temperature and precipitation play a role in driving mosquito infection rates and transmission of WNV, motivating efforts to predict infection rates based on prior weather conditions. Weather conditions and sequential patterns of meteorological events can have particularly important, but regionally distinctive, consequences for WNV transmission, with high temperatures and low precipitation often increasing WNV mosquito infection.

Local impact of temperature and precipitation on West Nile virus infection in Culex species mosquitoes in northeast Illinois, USA.

Background: Models of the effects of environmental factors on West Nile virus disease risk have yielded conflicting outcomes. The role of precipitation has been especially difficult to discern from existing studies, due in part to habitat and behavior characteristics of specific vector species and because of differences in the temporal and spatial scales of the published studies. We used spatial and statistical modeling techniques to analyze and forecast fine scale spatial (2000 m grid) and temporal (weekly) patterns of West Nile virus mosquito infection relative to changing weather conditions in the urban landscape of the greater Chicago, Illinois, region for the years from 2004 to 2008.

The emergence of west nile virus during a large outbreak in Illinois in 2002.

In 2002, the world's largest outbreak of neuroinvasive West Nile virus (WNV) disease occurred. Illinois reported 21% of the total cases in the United States, the most among all states. The epidemiology of WNV in Illinois in 2002 was examined to determine factors associated with severe disease and death.

Overwintering and establishment of Aedes albopictus (Diptera: Culicidae) in an urban La Crosse virus enzootic site in Illinois.

In 1997, Aedes albopictus (Skuse) was discovered in Peoria, IL, a known focus of La Crosse (LAC) virus transmission. This accidental introduction provided an opportunity to determine whether Ae. albopictus would reemerge in the spring or summer and, if successful overwintering occurred, to follow changes in the geographic range of Ae.