Health officials have confirmed the state's first human case of West Nile virus this year in the Weber-Morgan health district, prompting a warning for residents to stay vigilant against mosquitoes.

The case was reported about a month after the virus was discovered in mosquito pools in northern Utah. Two additional human cases are under investigation in Weber and Uintah counties, the Utah Department of Health and Human Services said in a statement.

The person who tested positive for the virus lives in the Weber-Morgan health district and is between the ages of 65 and 84, health officials said. He is hospitalized with a neuroinvasive case of the virus.

Last year, Utah reported 28 human cases of West Nile virus, three of whom died.

So far this year, mosquito abatement districts have identified 73 mosquito pools with the virus in Davis, Salt Lake, Tooele and Uintah counties. Two horses in Uintah County also contracted the virus.

"Mosquito season isn't over and Utahns should continue to protect themselves from mosquito bites," Hannah Rettler, vector-borne/zoonotic epidemiologist with the state health department, said in the statement. "Many more Utahns could become ill with West Nile virus if they don't take precautions to protect themselves from mosquito bites."

She said most people who are infected with the virus don't experience symptoms, but about 20% do experience flu-like symptoms. Fewer than 1% of cases develop serious illness, which can be life-threatening — especially for those ages 60 and older and those with certain medical conditions.

Anyone who develops serious symptoms of West Nile virus — including a high fever, severe headache, stiff neck, disorientation or confusion — should contact a health care provider, health officials said.

Here are steps to take to prevent mosquito bites:

  • Use insect repellent. Those containing 20% to 30% DEET are safe to use during pregnancy, according to health officials.
  • Limit your outdoor activities after the sun goes down, when mosquitoes are most active.
  • Wear clothing that covers as much skin as possible when you visit places where mosquitoes are most active.
  • Eliminate pools of standing water around your home as much as possible.

For more information about the West Nile virus, call your local health department or visit