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First Confirmed Human Case of West Nile Virus Contracted in Pinal County in 2021
Date: 8/26/2021

On August 24, 2021, Pinal County Public Health Services District confirmed the first West Nile Virus (WNV) case of the 2021 mosquito season in a Pinal County resident. The mosquito season starts in the summer and continues through fall every year.

WNV is a mosquito-transmitted disease, the most common in the continental United States. The disease was introduced in the country in 1999 and the first case in Arizona was detected in 2003. From 2016 to 2021, there have been 12 other confirmed cases and 12 probable cases in Pinal County.

Most people exposed to the virus don’t get sick, but about 20 percent develop minor symptoms like headache, fever, muscle and joint aches, nausea, and fatigue. In a very small proportion, less than one percent, the virus affects the nervous system, leading to a more serious illness.

People over 60 years old and/or with certain comorbidities, like diabetes, hypertension, and cancer, among others, are at greater risk to develop severe illness. WNV is not diagnosed only by symptoms and requires confirmatory lab tests by your healthcare provider.

Pinal County Public Health Services urges people to protect themselves and their families from West Nile and other diseases spread by mosquitoes: * WEAR long sleeves and pants. Create a barrier to mosquito bites by covering up * APPLY insect repellent. Use EPA-registered repellents such as those containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone * REMOVE standing water. Emptying water that accumulates in toys, tires, trash cans, buckets, clogged rain gutters, and plant pots will deny mosquitoes a place to lay their eggs and reproduce.

The Pinal County Environmental Health Vector Control program focuses on mosquito-borne disease prevention and reduction of the specific types of mosquitoes associated with these diseases.

Vector Control personnel routinely trap, identify and test mosquitoes for West Nile Virus. Mosquito abatement focuses on removal of breeding sites and biological control of disease-spreading mosquitoes where possible. Other abatement activities, such as mosquito fogging, are based on surveillance data.

Vector control personnel work with residents to remove or treat standing water on their property and in their neighborhoods to fight the bite and help prevent mosquitoes from spreading disease. View this video tp learn more about Pinal County's Vector Control Program:

If you would like information on mosquito prevention and control, or to file a complaint, visit the Pinal County Environmental Health Services webpage at, or call 866-287-0209.

For more information about West Nile Virus in Arizona please visit ADHS West Nile Virus page at or CDC West Nile Virus page at



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