Pima County reports first West Nile Virus Related death of season 

Two human cases of West Nile virus have been confirmed in Pima County in 2025, one case with symptom onset in 2024 and the recent fatal case with onset during this vector season.

The County also has seen its first detection of West Nile Virus in mosquitoes for this vector season. The mosquitoes detected are unrelated to the human case, indicating potential West Nile risk to the public.

In Arizona, mosquito-borne viruses are most likely to be spread from May through October during the peak of mosquito activity.

West Nile virus is typically spread through the bite of an infected mosquito. Most people infected don’t show symptoms, but about one in five may develop a flu-like illness with fever, headache, and body aches.  In rare cases—about one in 150—the virus can cause severe complications like encephalitis or meningitis, which may lead to paralysis, long-term disability, or death. Older adults, people with underlying health conditions, and those with weakened immune systems are at higher risk for severe illness.

Those experiencing symptoms especially following mosquito exposure are encouraged to contact a healthcare provider. Healthcare providers are encouraged to consider West Nile Virus in differential diagnoses.

Regardless of the hot and normally dry temperatures, mosquitoes are active day and night throughout the year. The best way to protect yourself and your family is to take measures to prevent mosquito bites.

Here are some preventive steps that you can easily take. Find more at pima.gov/mosquitoes:

• Keep mosquitoes off your body. Wear loose-fitting, light-colored clothing. Use insect repellent on exposed skin.

• Keep mosquitoes out of your yard. Walk through your yard and check for areas that collect water. Standing water is the ideal place for mosquitoes to breed, so change outdoor pet water daily and replace with fresh water and make sure things like plant containers, tires, or other items are not collecting water.

• Keep mosquitoes out of your house.  Check  window screens for holes and repair immediately. Do not leave doors open if you do not have a screen door to act as a mosquito barrier.

Good Reminders

• Use mosquito repellents that contain DEET, Picaridin, or Oil of Lemon Eucalyptus.

• Repair leaky pipes and outside faucets, and move air conditioner drain hoses frequently.

• Report mosquito breeding problems (e.g. green pools) to 520-724-7908

• Additional information about how to Manage Mosquitoes in Floodplains and Ponds