Final 2012 West Nile virus update:

Last year ranked as the second worst outbreak of neuroinvasive, non–neuroinvasive, and total West Nile virus (WNV) disease cases reported since WNV was first detected in the United States in 1999. The largest number of WNV cases was reported during 2003.

In 2012, all 48 contiguous states, the District of Columbia, and Puerto Rico reported WNV infections in people, birds, or mosquitoes. A total of 5,674 cases of WNV disease in people, including 286 deaths, were reported to CDC. Of these, 2,873 (51%) were classified as neuroinvasive disease (such as meningitis or encephalitis) and 2,801 (49%) were classified as non-neuroinvasive disease.