Arizona sees worst outbreak of West Nile Virus in the US

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By Jennifer Thomas By Jennifer Thomas

PHOENIX -- Nearly 20 percent of the nation's severe cases of West Nile Virus were found here in Arizona, which means we had the worst outbreak of the disease in the entire country in 2010.

Those numbers are part of a new report issued by The Centers for Disease Control and Prevention.

According to that report, a total of 159 confirmed cases of West Nile Virus were reported in Arizona through Nov. 30. A check of the USGS Disease Map for Arizona, posted on Dec. 7, puts the total at 161, showing the worst months to be July and September. At least 12 people have died.

West Nile Virus is spread by mosquitoes. The disease attacks the nervous system, which can lead to potentially fatal West Nile encephalitis and West Nile meningitis.

Health officials were surprised by the CDC report. They had believed West Nile Virus cases were more concentrated in areas where mosquito populations are larger and more prevalent.

West Nile Virus was first found in New York City in 1999, according to the CDC. It quickly spread throughout the country. Since then, it has caused seasonal epidemics and is now the leading cause of arboviral encephalitis.

In 2009, a total of 720 cases of West Nile Virus was reported from 38 states and Washington, D.C.