How long has West Nile virus been in the U.S.?
It is not known how long it has been in the US., but scientists from the U.S. Centers for Disease Control and Prevention believe the virus has probably been in the eastern U.S. since the early summer of 1999, and possibly longer. West Nile was first recognized in the United States in 1999 as the cause of severe illness and fatalities in humans in metropolitan New York City. The virus has since spread rapidly throughout the country.
