WNV Has Spread Rapidly

Since it was first detected in 1999, the virus spread rapidly throughout the U.S. and peaked in 2002–2003.

In which parts of the U.S. did most cases of human disease occur?

A color-coded map of the United States labeled 2003. A legend indicates that striped light blue marks states with avian, mammalian, or mosquito infections and includes Maine. Dotted yellow marks states that had between 1 and 100 human disease cases which includes the majority of the states. Dotted orange is 101 to 500 cases. Cross-hatched red is 501 to 1000 cases and includes Texas and North Dakota. Cross-hatched purple is over 1000 cases and includes South Dakota, Nebraska and Colorado. The only states with no recorded infections are Washington, Oregon, Alaska, and Hawaii.
West Nile virus infections recorded in 2003 in the U.S.