Utah News Dispatch
Utah’s first 2025 West Nile virus case reported in Salt Lake County
Culex species mosquitoes spread West Nile virus. (Photo courtesy U.S. Centers for Disease Control and Prevention)
Salt Lake County health officials have announced Utah’s first confirmed human case of West Nile virus this year.
The infected person is an adult diagnosed with neuroinvasive West Nile virus, a more severe form of the disease, according to a news release issued Thursday by the Salt Lake County Health Department.
The person was hospitalized earlier this month but is now recovering at home, according to the county.
“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,” the health department said, declining to release additional information about the person due to medical privacy laws.
So far this season, Salt Lake County’s three mosquito abatement districts have detected West Nile virus in 24 different mosquito samples throughout the county. Statewide, 108 mosquito samples have tested positive, according to the county health department.
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“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,” county health officials said.
West Nile virus was first detected in the U.S. in 1999. In 2003, Utah saw its first confirmed case.
Last year, Utah 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. That year, the state reported no deaths from the disease, but in 2023 one person died.
However, health officials warned that the virus can be difficult to detect, and it’s likely more prevalent than statistics show.
“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,” county health officials said.
West Nice virus can cause mild to severe illness, and many may not even know when they have been infected.
“It is estimated that less than 1% of people infected with (West Nile virus) will develop the neuroinvasive form of the disease, which can result in debilitating long-term complications or death,” health officials said.
Symptoms of can infection can appear within two to 14 days of a mosquito bite. They include fever, headache and body aches. More severe infections may include high fever, neck stiffness, disorientation, coma, tremors and muscle weakness or convulsions.
Those over the age of 50 and people with weakened immune systems are at the highest risk of illness from West Nice virus, health officials said, but anyone can become ill from the bite of an infected mosquito. The virus is not transmissible from person to person.
“There is no specific treatment for (West Nile virus) infection other than to treat symptoms,” county health officials said, urging anyone who thinks they might have been infected to contact their health care provider.
Even though only some mosquitos carry the virus, “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 continues on until the first hard freeze.
Salt Lake County health officials urged Utahns to do the following to protect themselves from the disease:
- Use an EPA-registered mosquito repellent with DEET, picaridin, IR3535 or oil of lemon eucalyptus. Follow package directions for application.
- After dusk, wear long sleeves and pants.
- Drain standing water in yards (in 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 can’t get inside.
- Keep weeds and tall grass cut short. Adult mosquitoes look for these shady places to rest during the hot daylight hours.
