Illinois health officials are warning people to watch out for deer ticks, which are thriving because of the mild winter and early spring weather.

Most of the pests, also known as blacklegged ticks, normally die off during Illinois' cold winter.

Linn Haramis, an entomologist with the Illinois Department of Public Health, says that didn't happen this year.

She notes that the warmer weather has drawn more people and their pets outside, increasing their exposure to ticks.

Some ticks can transmit Lyme disease by biting humans and their pets. It's treatable within a few weeks of infection. But beyond that, the diseases may damage the joints, heart and nervous system.