September 15, 2023

SLCoHD Reports County’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 the county this year. The infected person is an adult diagnosed with neuroinvasive West Nile virus, a more severe form of the disease; they remain hospitalized. Due to medical privacy laws, SLCoHD cannot release additional information about the individual.

This latest human case is the fourth in the state, joining two in the TriCounty Health District and one in the Weber-Morgan Health District.

So far this season, the three mosquito abatement districts in Salt Lake County have detected West Nile virus in 77 different mosquito pools throughout the county. "Mosquito pool" is the term used for a group of mosquitoes caught and tested out of a single trap; it is not related to swimming pools or pools of water.

“There are a growing number of mosquitoes carrying the disease,” said Dr. Angela Dunn, SLCoHD executive director, “so it is now especially important that people protect themselves from mosquito bites, particularly in the hours from dusk to dawn.”

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 exposure opportunities during mosquito season (which will continue until the first hard freeze):

• Use an EPA-registered mosquito repellent with DEET, permethrin, 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.
• 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 neuroinvasive disease, which can result in debilitating long-term complications or death. Symptoms of WNV infection appear within 2 to 14 days 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 5 people in the state contracted the virus; all recovered. In 2021, 28 people were confirmed to have West Nile virus and 3 people died. 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.