BOX ELDER COUNTY, Utah - Mosquito samples from three Utah counties tested positive for West Nile virus, and specialists are advising the public to take precautions.

The Utah Department of Health said Monday mosquitoes in Box Elder, Davis and Uintah counties are infected with West Nile.

"This is the first week during the summer that we have had positive pools," said Rebecca Ward, health educator for the Utah Department of Health Epidemiology Bureau.

She said a pool is a group of dozens of mosquitoes, collected in certain areas and tested for the disease.

According to the Box Elder Mosquito Abatement District, the mosquitoes in Box Elder County came from the Willard Bay North Marina.

"The virus has only been confirmed near Willard Bay thus far, but it is possible that the virus could be more widespread at this point," the abatement district said in a statement. "We are announcing this to make the county aware that West Nile virus season has started."

Ward said most people who contract West Nile don't show symptoms, but for those who do, the most common symptoms include feeling tired and achey.

"One in five people will develop some of those symptoms-- it'll be like joint aches, and muscle aches and symptoms like that, and maybe vomiting, diarrhea or rash," she explained.

She said in rare cases, West Nile can lead to serious neurological damage. Ward said symptoms can develop 2 to 14 days after a mosquito bite. Mosquitoes are most active in the early morning and late evening.

The best prevention, she said, is to avoid mosquito bites by wearing long-sleeved shirts and pants, and using mosquito repellent with DEET, oil of lemon or Picaridin.