OMAHA, Neb. (AP) — Health officials are warning those in eastern Nebraska’s Douglas County to take precautions after West Nile virus is found in mosquitoes in the county.

The Douglas County Health Department says in a news release that four local mosquito pools at two locations have tested positive for the mosquito-borne illness.

The pools are located at Seymour L. Smith Park in Ralston and Zorinsky Lake Park in western Omaha.

The department says high populations of mosquitoes have been reported since May. Residents are urged to apply mosquito repellant and wear long-sleeved shirts, pants and socks and shoes, particularly at dawn and dusk, when mosquitoes are most active. Residents should also remove standing water to prevent mosquito breeding.

Those who contract West Nile can suffer symptoms ranging from mild flu-like symptoms to death.