West Nile Virus Yearly Spread Map

How has West Nile Virus spread across the US since its initial outbreak in 1999? Learn which states are currently at risk for West Nile Virus.

In 1999, the West Nile Virus was first found in New York City. Cases seemed to be isolated mostly in New York State, with a few in Connecticut and New Jersey.

By 2000, most of New York State had been hit, as well as Massachusetts, Connecticut and Rhode Island. Going south, the virus was found in Pennsylvania, New Jersey, Delaware, and other states down to a tiny location in North Carolina.

In 2001, the virus spread westward. It was now found in all states east of the Mississippi except Georgia and West Virginia. Florida was especially hard hit. In addition, small spots were affected in Missouri, Ohio, Arkansas and Louisiana.

By 2002, the virus had solidly spread westward, and high media attention meant that just about any bird that fell visibly from West Nile was counted. Maps were solidly covered with sightings from the eastern seaboard out to the Rocky Mountains. The only states clear were Washington, Oregon, California, Idaho, Nevada, Utah and Arizona. Even of these, small spots were found in California, Washington and Idaho.

In 2003, only Washington, Oregon, Hawaii and Alaska appeared to be untouched by West Nile. Maine had no human infections, but did have bird infections. The most cases were in Colorado, with 2947 cases being reported.

So far in 2004, the first human case was reported in New Mexico. Animal infections have been found in about half of all US states so far this year.

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