Two cases of the more severe form of West Nile virus have been reported in Johnson County, and four regions of the state are at high risk for the mosquito-borne disease.

The Kansas Department of Health and Environment reported two cases of neuroinvasive West Nile virus, which includes swelling of the brain or brain tissue and may cause death. More typically, one in five people bitten by a mosquito carrying the virus develops a fever and a variety of symptoms, which can include headache, weakness, muscle pain and a rash.

Areas under a high-risk warning for West Nile are north central, south central, northwest and southwest Kansas. The northeast and southeast areas are at moderate risk, a KDHE report said.

“Although for most people West Nile virus may not cause a great deal of concern, we encourage residents, especially our vulnerable populations, to take steps to prevent infection because of the potential for complications,” said Greg Lakin, chief medical officer at KDHE.

To protect against West Nile, KDHE recommends that anyone going outdoors use insect repellent containing an EPA-registered active ingredient on skin and clothing, including DEET, picaridin, oil of lemon eucalyptus, or IR3535.

Many mosquitoes are most active at dusk and dawn, so it is important during those hours to stay indoors or wear long sleeves and pants and use repellent.

The elderly or those with a weakened immune system should consider limiting their exposure outside during dusk and dawn when the Culex species mosquitoes, which carry West Nile, are most active. Keeps doors and windows closed, and maintain screens, to keep mosquitoes out of the house.

Eliminate standing water on your property, a KDHE release said, because it is a breeding ground for mosquitoes.

Most West Nile infections occur in the late summer and early fall. As of July 24, 39 cases of human West Nile had been reported nationally. There have been more than 600 cases of the most severe form of West Nile and 30 deaths in Kansas from 1999 to 2017.