Utah Reports First Human Case of West Nile Virus for 2025

Utah’s initial human case of West Nile virus for 2025 has been confirmed in Salt Lake County. The affected person was hospitalized due to a severe form of the virus but is now recovering at home.

Public health officials indicate that the infection likely occurred in late July, near the Jordan River in the southern part of the county. Due to health privacy laws, specific details about the individual are not available.

According to the health department, three mosquito abatement districts in Salt Lake County—Magna, Salt Lake City, and South Salt Lake Valley—have shown positive test results for the virus. A total of 108 mosquito samples statewide have tested positive.

Health officials collect mosquitoes to test for the presence of the virus, referring to these collections as “mosquito pools.” However, since mosquitoes can travel several miles, everyone in the vicinity is advised to take precautions.

About West Nile Virus

West Nile virus is mainly transmitted by birds and certain mosquitoes. Humans contract the virus when bitten by mosquitoes that have fed on infected birds. Unlike birds, humans don’t have high enough levels of the virus in their blood to infect other mosquitoes, making them “dead-end hosts,” according to the Centers for Disease Control and Prevention.

The CDC also mentions that while it’s uncommon for a person to spread the virus through blood transfusions, organ transplants, or during pregnancy, it can happen. Consequently, those recently diagnosed with West Nile virus should refrain from donating blood or bone marrow for 120 days.

Symptoms of the virus can emerge within two days to two weeks and may manifest as fever, headache, body aches, vomiting, diarrhea, or rash. The severe form, known as neuroinvasive West Nile virus, can be very serious or even deadly. Symptoms of this severe case can include high fever, stiff neck, disorientation, coma, tremors, and severe muscle weakness.

While approximately 1 in 5 infected individuals display symptoms, roughly 1 in 150 may develop the more serious, sometimes fatal illness.

Those particularly at risk for symptomatic West Nile virus include individuals with weakened immune systems and adults over the age of 50.

Currently, there is no specific treatment for the virus; care mainly focuses on managing symptoms.

Preventing West Nile Virus

As there is no vaccine available, the best strategy for prevention is to avoid mosquito bites.

The Salt Lake County Health Department provides the following recommendations until the first hard freeze:

• Utilize an EPA-registered mosquito repellent containing DEET, picaridin, IR3535, or oil of lemon eucalyptus. Be sure to follow the instructions on the packaging.
• If outside during dusk and dawn—when the mosquitoes that transmit the illness are most active—wear long sleeves and pants.
• Eliminate standing water in yards, including in plant trays, pet dishes, buckets, and discarded tires.
• Keep roof gutters clear of debris.
• Stock garden ponds with mosquito-eating fish or apply mosquito dunks. Help is available from local mosquito abatement districts.
• Ensure that door and window screens are intact to prevent mosquitoes from entering your home.
• Maintain short grass and weed growth, as adult mosquitoes seek out these shaded areas during the heat of the day.