Stanislaus County Health Services Agency – Public Health has confirmed the first death associated with neuro-invasive form of West Nile virus (WNV) in a Stanislaus County resident this year. The individual was an adult under the age of 50.

As of Sept. 22, 2026, 11 human cases of West Nile virus had been reported in Stanislaus County in 2026, including this death. This has been a particularly active West Nile virus and mosquito season, and Public Health is urging all residents to take precautions to prevent mosquito bites.

“We are saddened to report the first West Nile virus-associated death in Stanislaus County this year, and we extend our condolences to the individual’s family and loved ones,” said Dr. Thea Papasozomenos, Stanislaus County Public Health Officer. “While the risk of severe illness increases with age and certain health conditions, West Nile virus can cause serious illness in people of any age. This is an important reminder that everyone should take precautions to prevent mosquito bites.”

West Nile virus is primarily transmitted to people through the bite of an infected mosquito. Most people infected with WNV do not develop symptoms. Some people may develop fever, headache, body aches, joint pain, vomiting, diarrhea, or rash. In rare cases, the virus can cause severe illness affecting the brain and nervous system, including encephalitis or meningitis, and can result in long-term health complications or death.

Although older adults and people with certain underlying medical conditions or weakened immune systems are at greater risk of severe illness, anyone can become infected and develop serious illness. There is currently no vaccine or specific treatment for West Nile virus in humans.

With elevated West Nile virus activity this season, residents should continue taking precautions:

• Use insect repellent. Choose an EPA-registered insect repellent and follow label directions.
• Wear long sleeves and pants when practical, particularly during dawn and dusk when mosquitoes that spread West Nile virus are most active.
• Keep mosquitoes outside. Make sure doors and windows have properly fitted screens and repair any holes or tears.
• Dump and drain standing water. Regularly empty water from buckets, flowerpots, birdbaths, tires, pet dishes, and other containers where mosquitoes can breed.
• Maintain swimming pools and report neglected pools to your local mosquito abatement district.

Mosquito activity can continue as long as weather conditions remain favorable. Residents should continue protecting themselves from mosquito bites throughout the remainder of the mosquito season. Residents who notice an unusual number of mosquitoes or have concerns about mosquito activity can contact their local mosquito control agency, East Side Mosquito Abatement District at 209-522-4098.

Dead birds can be an early warning sign of West Nile virus activity. Residents can report dead birds to the California West Nile Virus Dead Bird Hotline at 1-877-968-2473 or through the California West Nile Virus website.

Public Health and local mosquito abatement districts will continue monitoring West Nile virus activity and encourage residents to remain vigilant throughout the remainder of the season.