Utah County has confirmed its first human case of West Nile virus for the 2026 season, according to a report published September 1. The case, announced by the Utah County Health Department on Monday, Aug. 31, involves neuroinvasive disease, which is the most serious form of the illness.
Neuroinvasive West Nile virus can lead to meningitis, encephalitis, or acute flaccid myelitis and may require hospitalization. While most people infected with the virus do not develop symptoms, about one in five people develop fever, headache, body aches, joint pain, vomiting, diarrhea, or a rash. Warning signs of the neuroinvasive form include severe headache, high fever, neck stiffness, confusion, tremors, seizures, and muscle weakness. Less than 1% of people infected with the virus develop the neuroinvasive form.
The Utah County Health Department is urging residents in areas including Lehi, Alpine, Highland, and Cedar Hills to take precautions against mosquito bites. The department and Utah County Mosquito Abatement are currently reviewing surveillance data and conducting assessments in the area where the case was identified. Aislynn Tolman-Hill, a media contact for the health department, stated that the case serves as an important reminder that the virus is present in the community and can cause serious illness.
The case arrives during a year with elevated mosquito activity across Utah. As of Aug. 22, Utah had recorded 15 human West Nile cases in 2026. This compares to one case at the same time in 2024 and six cases in 2025. Additionally, the percentage of tested mosquito pools that tested positive statewide was 12.3%, an increase from 2.4% in 2024 and 3% in 2025.
To prevent bites, the health department recommends using insect repellent containing DEET, picaridin, or oil of lemon eucalyptus, especially during dawn and dusk. Other recommendations include wearing long sleeves and pants when possible, ensuring window and door screens are intact, and removing standing water around homes. Residents can file service requests for heavy mosquito activity or standing water through the Utah County Mosquito Abatement section of the health department's website.
