By NewsDesk  @infectiousdiseasenews

In a follow-up on the West Nile virus (WNV) situation in Arizona, state health officials report 132 confirmed and 78 probable cases through September 29.

Maricopa County, which includes the city of Phoenix, accounts for 84 percent of the confirmed cases with 115, and reports 174 total cases. Neighboring Pinal County has recorded 26 total cases to date.


Other counties reporting WNV cases include Pima, Apache, Mohave and Yavapai.

The Arizona Department of Health Services also reports 10 WNV deaths, the majority from Maricopa County.

West Nile Virus is a type of virus that mostly infects birds but can also infect horses and humans. WNV did not appear in Arizona until 2003, but since that time the virus has been active in Arizona.

Since the first cases were reported in 2003, Arizona saw 1939 cases through 2020, with 2004 seeing the most in a single year with 391.

West Nile virus is typically spread through the bite of an infected mosquito. Although it can cause severe disease, only about 1 in 5 of those infected will develop any symptoms at all. Those who do develop symptoms usually experience a flu-like illness including fever, headache, body aches and muscle weakness.

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Rarely, about 1 in 150 people infected can develop encephalitis or meningitis (inflammation of the brain or of the spinal cord). This more severe form of the disease can present with headache, neck stiffness, vision loss, paralysis and other neurologic symptoms. These severe cases can lead to very prolonged illness, permanent paralysis or death.

Those who are over 60 years old, have underlying medical conditions or have depressed immune systems are at higher risk for the more severe form of West Nile virus.