SALT LAKE CITY — Utah’s first two human cases of West Nile virus this year have been confirmed in Salt Lake County and Washington County, health officials said.

The person in Salt Lake County has a neuroinvasive — or more serious — form of the disease that can be life-threatening. The patient was in a hospital as of Monday, the Salt Lake County Health Department said in a statement. Additional information about the person was not released due to privacy laws.

Salt Lake County has seen 21 different mosquito groups throughout the area that have tested positive for the virus this year, health officials said. Mosquitos with the virus have also been found in southern Utah.

“There are a growing number of mosquitoes carrying the disease,” Ilene Risk, Salt Lake County epidemiology bureau manager, said in a statement. “So it is now especially important that residents protect themselves from mosquito bites, particularly in the hours from dusk to dawn.”

Most people recover from the virus. But about 1 in 150 develop a severe, sometimes fatal illness that can include high fever, headache, neck stiffness and other symptoms, according to the Centers for Disease Control and Prevention.

For more information about the virus, visit cdc.gov/westnile.