Illinois health officials announced mosquitoes in DuPage and Cook counties have tested positive for West Nile virus. They said the infected mosquitoes have shown up earlier than usual due to the mild winter and warm spring.

Linn Haramis, an entomologist with the Illinois Department of Public Health, said people should start taking precautions now, even though human cases of the virus typically don’t start popping up until late summer.

“Even if you’re not seeing a lot of mosquitoes in the summertime, use insect repellant. It only takes a few seconds. It could help avoid a big problem,” he said.

In addition to using insect repellant, Haramis said getting rid of standing water around the house where mosquitoes breed is another precaution people can take.

Illnesses from the virus are usually mild but can be deadly especially for people over 50. There were 34 confirmed West Nile cases and three deaths last year. Illinois saw its highest number of cases in 2002, with 225 reported cases and 22 deaths, according to the Department of Public Health.