Given the record-breaking water season in Utah, mosquitoes are abundant this summer. Fortunately, only some of them spread illnesses.

More than 200 types of mosquitoes live in the continental U.S. but only about 12 types spread germs that can make people sick. Fifty different species are found in Utah. Other mosquitoes bother people and are considered nuisance mosquitoes.

Public health officials say 2 human cases of West Nile virus have been diagnosed so far in 2023. One case lives in the TriCounty health district area; the other case lives in the Weber-Morgan health district. In 2022, there were 5 reported human cases of West Nile virus in Utah, with no deaths.

In addition to those confirmed human cases, as of August 30, 2023, 170 positive mosquito pools have been identified all across the state in Bear River, Davis, Duchesne, Grand, Millard, Salt Lake, Tooele, Uintah, Utah, Washington, and Weber counties. Additionally, there 2 horses, one in Garfield and one in Duchesne have tested positive for WNV along with one positive sage grouse from Wasatch County.  Mosquitoes that carry the St. Louis encephalitis virus have also been found in the southwest part of Utah.

Kacy Nowak, vector-borne/zoonotic epidemiologist with the Utah Department of Health and Human Services says, “Mosquito season isn’t over and Utahns should continue to protect themselves from mosquito bites.” Nowak continues, “Many more Utahns could become ill with an illness carried by mosquitoes if they don’t take precautions to protect themselves from mosquito bites.”

To protect yourself:

  • Use insect repellent when you go outdoors. Repellents containing 20% to 30% DEET are recommended and safe to use during pregnancy. For more information about insect repellents, visit the EPA information page. Always follow label directions.
  • Limit outdoor activities from dusk to dawn, when mosquitoes are most active, especially for the first 2 hours after sunset.
  • When outdoors, wear long pants, long-sleeved shirts, and socks in areas where mosquitoes are active.

To reduce mosquitoes around your home:

  • Drain and remove all sources of standing water on your property to prevent mosquito development.
  • Empty water from pet dishes, flower pots, wading pools, backyard ponds, buckets, tarps, tires, and puddles at least once a week.
  • Report bodies of stagnant water to your local mosquito abatement district (MAD). Visit http://www.umaa.org/ for a list of MADs.
  • Try to keep doors and windows shut and keep screens in good condition. Make sure they fit tightly.

Nowak says most people infected with an illness caused by a mosquito bite won’t have symptoms. About 20% of infected people will have flu-like symptoms, while fewer than 1% develop a serious, potentially deadly illness. People aged 60 years and older and those with certain medical conditions are at greater risk of serious illness.  See a healthcare provider if you develop symptoms of a mosquito bite illness including high fever, severe headache and stiff neck, disorientation, and confusion.

Since surveillance began in 2003, an average of 25 human cases of West Nile virus have been confirmed In Utah each year, with a wide range between 1 and 158 cases. There has only been one confirmed human case of St. Louis encephalitis in 2016.

For more information about mosquito-bite-related illnesses, call the Summit County Health Department at 435-333-1500 or visit https://epi.utah.gov/west-nile-virus/.