10 States Where Rare and Exotic Diseases Lurk

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Credit: Corbis

Arizona

Few states have escaped West Nile, a mosquito-borne virus that has infected more than 30,000 people and killed countless crows and other birds since entering the U.S. in 1999.

But lately Arizona is catching the worst of it. In 2010, it had 107 cases of an especially virulent form of the disease that can cause seizures, nerve damage, and even death.

Although the virus spreads to the brain in less than 1% of cases, people over 50 are at the highest risk. Arizona, a favorite retirement destination, is reminding residents to wear insect repellent and eliminate standing water in a "Fight the Bite" campaign.

Next: California