West Nile Virus Incidence in the United States 1999-2012

West Nile virus (WNV) is a flavivirus vectored primarily by culicine mosquitoes with birds as the major natural reservoir hosts. WNV disease in humans ranges in severity from asymptomatic infections to mild fever to life-threatening neuroinvasive disease. Prior to 1999, WNV was found in Africa, Asia, Europe, the Middle East, and Australia. The first human cases in the Western Hemisphere were detected in New York City during the summer of 1999. The virus subsequently dispersed across North America, reaching the Pacific Coast in 2003 and spreading to all 48 of the conterminous United States by 2006. Surveillance data documenting the spread of WNV offers a rare opportunity to visualize and study the geographic expansion of an emerging infectious disease along with its subsequent endemic cycles. Therefore, we developed this web visualization tool to facilitate the exploratory analysis of the spatial and temporal patterns of WNV in the United States.

Data were obtained from the USGS/CDC ArboNET Maps website (http://diseasemaps.usgs.gov) and include the total number of reported cases (neuroinvasive and non-neuroinvasive) of human WNV disease for each county. This website was developed by the Geographic Information Science Center of Excellence at South Dakota State University as part of the Epidemiological Applications of Spatial Technologies (EASTWeb) project and is supported by the National Institutes of Health, National Institute of Allergy and Infectious Diseases (Grant R01-AI079411). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. For more information about the EASTWeb project contact Dr. Michael C. Wimberly.


WNV Incidence per 100,000