Dozens of people from at least 25 suburban Cook County schools have been sickened with an intestinal illness.

That’s up from only four schools less than two weeks ago.

Cook County public health officials have traced some cases to a type of Norovirus and the others have similar symptoms. These include vomiting, diarrhea, stomach cramps and mild fever.

Noroviruses are very contagious and are spread orally, from contaminated food, or touching contaminated surfaces and then the mouth.