Utah health officials reported two human cases of West Nile virus in Salt Lake County as of August 2026, following a period of increased mosquito activity. The most recent reports include a case of neuroinvasive West Nile virus, a severe form of the disease, which was confirmed by the Salt Lake County Health Department.
Severe Case Confirmed
The Salt Lake County Health Department announced that an adult was diagnosed with neuroinvasive West Nile virus, a more severe form of the disease. According to the health department, the individual was hospitalized earlier this month but is currently recovering at home. Investigation into the case suggests the infection likely occurred in late July near the Jordan River in the southern portion of Salt Lake County. Due to medical privacy laws, the department could not release further specific details regarding the patient.
Rising Mosquito Activity
The threat of West Nile virus in the region has grown as mosquito testing continues to return positive results. In Salt Lake County, the three mosquito abatement districts—the Magna Mosquito Abatement District, the Salt Lake City Mosquito Abatement District, and the South Salt Lake Valley Mosquito Abatement District—have detected the virus in 24 different mosquito samples. This contributes to a statewide total of 108 mosquito samples testing positive for the virus.
Underreporting Risks
Public health officials have warned that the current infection numbers may be higher than reported due to the nature of the virus. Because only 20% to 30% of infected people experience any symptoms at all, and many notice only minor, flu-like symptoms, the actual prevalence of West Nile virus may be more widespread than official case counts indicate.
Prevention and Protection
The risk of West Nile virus remains present through the remainder of the season, which typically continues until the first hard freeze. Health officials emphasize that while only some mosquitoes carry the virus, there is no way for residents to distinguish between an infected and a non-infected mosquito. Consequently, the Salt Lake County Health Department recommends minimizing all exposure opportunities.
Community Mitigation Steps
To reduce the risk of infection, health officials recommend using EPA-registered mosquito repellents containing DEET, picaridin, IR3535, or oil of lemon eucalyptus. Residents are advised to wear long sleeves and pants after dusk and to drain standing water from yards, such as from old tires, pet dishes, buckets, or potted plant trays. Additionally, keeping roof gutters clear of debris and maintaining garden ponds with mosquito-eating fish or mosquito dunks can help mitigate mosquito populations. The department also suggests ensuring window and door screens are in good condition to prevent mosquitoes from entering homes.
Disease Symptoms and Severity
West Nile virus is the leading cause of disease spread by mosquitoes in the contiguous United States. Most infections result in mild illness, but less than 1% of infected individuals develop the neuroinvasive form, which can lead to debilitating long-term complications or death. Symptoms of the infection typically appear within 2 to 14 days of a mosquito bite and include fever, headache, and body aches. More severe cases may involve high fever, neck stiffness, disorientation, coma, tremors, or muscle weakness and convulsions.
Historical Trends in Utah
The historical context of the virus in Utah shows fluctuating patterns of activity. In 2024, Utah recorded no deaths from West Nile virus, though one Utahn died from the disease in 2023. During the 2025 season, public health officials confirmed that 14 people in the state contracted the virus, 12 of whom developed the neuroinvasive form of the disease. West Nile virus was first detected in the United States in 1999 and was first identified in Utah in 2003.
