Hundreds of deer in the Chicago area have been killed by a virus previously unknown in the area.

Roughly 200 deer in Cook County have died. Six suspected cases have been reported in Kane County.

The disease is known as EHD, or epizootic hemorrhagic disease. It's a virus that kills deer in about a week and is spread among them by bites from flies known as midges.

The disease cannot be passed to humans or pets.

Cook County Forest Preserve District wildlife biologist Chris Anchor says the virus is typically found in other parts of the Midwest and in the Northeast.

He suspects the mild winter and hot summer helped it spread to northern Illinois. The first case was two weeks ago.