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Event title

United States - Maricopa County, Arizona accounts for about half the West Nile virus cases in the US

Event category

Biological origin - Infection hazard

Severity

Low

Event date (UTC)

2021-11-25 07:24:15

Last update (UTC)

2021-11-25 07:24:15

Latitude

33.348831

Longitude

-112.4912

Area range

County wide event

Address/Affected area(s)

Maricopa County, Arizona

Health officials in Maricopa County, Arizona are now reporting 1,091 total human West Nile virus (WNV) cases through November 23 this year. This total accounts for roughly half the total cases in the United States year to date (1,974 total cases reported by the CDC through Nov. 16). The previous annual record in of 355 cases was set in 2004. County officials also report 79 deaths due to the mosquito-borne disease. In all of 2000, Maricopa County saw three cases and one death. Melissa Kretschmer with the Maricopa County Health Department said a dry 2020 season followed by this very wet monsoon season contributed to more standing water leading to more mosquitoes. Statewide, Arizona has reported 1,233 total confirmed and probable cases and 90 fatalities. Pinal and Pima counties recorded cases in the double digits with 94 and 74 total cases, respectively. 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. 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.

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