Q. How many cases of West Nile disease in humans have occurred in the U.S.?

A. CDC's Statistics, Surveillance, and Control page contains maps showing the distribution of West Nile Virus-related human disease cases, by state, in the U.S.

Please see CDC's 2006 case count for the number and nature of human cases of West Nile Virus-related disease reported in the U.S. in 2006.

In 2001, there were 66 human cases of severe disease and 9 deaths. In 2000, 21 cases were reported, including 2 deaths in the New York City area. In 1999, 62 cases of severe disease, including 7 deaths, occurred in the New York area.

No reliable estimates are available for the number of cases of West Nile encephalitis that occur worldwide.

Q. What proportion of people with severe illness due to West Nile Virus die?

A. Among those with severe illness due to West Nile Virus, case-fatality rates range from 3% to 15% and are highest among the elderly. Less than 1% of persons infected with West Nile Virus will develop severe illness.