The Salt Lake County Health Department has confirmed the first human case of West Nile virus in a county resident this year. The infected individual is an adult who is expected to make a full recovery.
This marks the second confirmed human case of West Nile virus in Utah this season, following a case reported by the Bear River Health Department in late June.
Mosquito testing indicates an increase in the virus compared to previous years. In Salt Lake County, three mosquito abatement districts have detected West Nile virus in 86 different mosquito samples so far in 2026. Statewide, 296 mosquito samples have tested positive.
This represents a significant increase from previous years at this time. In 2024, 18 samples had tested positive statewide, while in 2025, 39 samples had tested positive at this time.
Health officials advise that because mosquitoes can travel several miles, all residents should take precautions against bites. Recommended measures include using EPA-registered mosquito repellents containing DEET, picaridin, IR3535, or oil of lemon eucalyptus. Residents are also encouraged to wear long sleeves and pants after dusk, drain standing water in yards, keep gutters clear, and ensure window and door screens are in good condition.
West Nile virus can cause illness ranging from mild to severe. Symptoms typically appear within 2 to 14 days and can include fever, headache, and body aches. Severe cases may involve high fever, neck stiffness, disorientation, coma, tremors, and muscle weakness or convulsions.
It is estimated that less than 1% of infected individuals will develop the neuroinvasive form of the disease, which can lead to death or long-term complications. People over age 50 and those with weakened immune systems face the highest risk, though anyone can be infected. There is no specific treatment for the virus other than treating symptoms.
West Nile virus was first detected in the United States in 1999 and in Utah in 2003. Last year, 49 people in Utah were known to have contracted the virus; 39 of those cases resulted in the neuroinvasive form of the disease, and four deaths were recorded. Because many infected people may not show symptoms, officials suggest the actual prevalence of the virus may be higher than reported case numbers indicate.
