Utah County health officials have reported the county’s first case of West Nile virus — and are planning more treatments to areas where mosquitoes gather.

The Utah County Health Department reported Monday that someone in the county contracted a neuroinvasive case of the virus, which officials said is the more serious form of the illness.

The county health department said it’s clear West Nile virus is circulating in the county, because of the confirmed human cases and a high number of mosquito pools. Health officials first found mosquitoes carrying West Nile virus in Utah County in mid-July.

As of Aug. 22, the Utah Department of Health and Human Services has reported 15 positive cases of West Nile virus in humans statewide. Five cases have been reported in Salt Lake County; other cases have been reported in Davis County, the Bear River Health District and the Weber Morgan Health District. The first case was reported June 29.

According to health officials, most people who are infected with West Nile virus don’t develop symptoms, but one in five do. The symptoms include fever, headache, body aches, nausea and vomiting, and swollen lymph nodes or a skin rash.

The neuroinvasive form of the virus is rare, but the outcomes can be severe — leading to meningitis, encephalitis or paralysis. Symptoms in these cases include high fever, neck stiffness, disorientation, seizures or muscle weakness.

Anyone who develops symptoms should contact their healthcare provider immediately, health officials say.

Utah County Mosquito Abatement is adding the number of assessments it makes of mosquito-prone areas, and is mounting targeted treatments in areas where the virus has been identified.

The Salt Lake County Health Department reported on Aug. 12 that more than a quarter of the samples taken by the Salt Lake City Mosquito Abatement District that week were positive for West Nile virus. The typical rate in August is under 5%. Similar levels were found in samples in the Magna and Southern Salt Lake Valley districts.

The Utah County Health Department recommended these steps to prevent mosquito bites:

• Wear insect repellent — such as DEET, picaridin, IR3535 or oil of lemon eucalyptus — when outdoors.

• Wear long sleeves and long pants when outside at dawn or dusk, when mosquitos are most active.

• Dump and drain standing water around the home, particularly in small containers — like buckets, bird baths, flower pots or clogged gutters — where mosquitos can breed quickly.

• Keep screens on windows and doors in good repair.

• Use extra caution if you’re older, have underlying health conditions, or are at higher risk of severe illness.