Salt Lake County Reports Utah’s First Human WNV Case of the Year

SALT LAKE COUNTY—The Salt Lake County Health Department (SLCoHD) announced today the first human case of West Nile virus (WNV) in Utah this year. The infected person is an adult diagnosed with neuroinvasive West Nile virus, a more severe form of the disease; they were hospitalized earlier this month but are now recovering at home. Public health's investigation has determined they were likely infected in late July near the Jordan River in the southern half of Salt Lake County. Due to medical privacy laws, SLCoHD cannot release additional information about the individual.

So far this season, the three mosquito abatement districts in Salt Lake County (Magna Mosquito Abatement District, Salt Lake City Mosquito Abatement District and South Salt Lake Valley Mosquito Abatement District) have detected West Nile virus in 24 different mosquito samples throughout the county. Statewide, 108 mosquito samples have tested positive. Because mosquitoes can travel several miles, everyone in the area—regardless of exact location—should take precautions against mosquito bites to avoid exposure to the virus.

Although only some mosquitoes carry WNV, there is no way for residents to tell which mosquitoes may be infected, so it is important to minimize all exposure opportunities during mosquito season (which will continue until the first hard freeze):

• Use an EPA-registered mosquito repellent with DEET, picaridin, IR3535 or oil of lemon eucalyptus; follow package directions about application.
• After dusk, wear long sleeves and pants
• Drain standing water in yards (old tires, potted plant trays, pet dishes, toys, buckets, etc.).
• Keep roof gutters clear of debris.
• Clean and stock garden ponds with mosquito-eating fish or mosquito dunks (contact your local mosquito abatement district for assistance).
• Ensure door and window screens are in good condition so mosquitoes cannot get inside.
• Keep weeds and tall grass cut short; adult mosquitoes look for these shady places to rest during the hot daylight hours.

WNV can cause mild to severe illness and many people may not even know they have been infected. It is estimated that less than 1% of people infected with WNV will develop the neuroinvasive form of the disease, which can result in debilitating long-term complications or death. Symptoms of WNV infection appear within 2 to 14 days of a mosquito bite and include fever, headache and body aches. More severe infections may include high fever, neck stiffness, disorientation, coma, tremors and muscle weakness or convulsions.

People over age 50 and people with weakened immune systems are at the highest risk of illness due to WNV, but anyone can become ill from the bite of an infected mosquito. WNV is not transmissible from person to person.

There is no specific treatment for WNV infection other than to treat symptoms. If you think you have WNV infection, contact your health care provider.

WNV was first detected in the U.S. in 1999 and in Utah in 2003. Last year, public health officials confirmed that 14 people in the state contracted the virus and 12 of those resulted in the neuroinvasive form of the disease. In 2024 there were no recorded deaths from WNV in Utah; one Utahn died from the disease in 2023. Because only 20-30% of infected people will have any symptoms at all—and many of those will notice only minor, flu-like symptoms—it's likely that infection with WNV is more prevalent than the reported case numbers indicate.