CARY, Ill. (CBS) – It’s a highly contagious disease and it was once nearly eradicated, but now whooping cough is making a comeback in our area.

In fact, new numbers out Thursday show 29 confirmed cases in McHenry County alone and there’s more than a dozen other suspected cases there.

As CBS 2′s Suzanne Le Mignot reports, whooping cough is contagious, but also preventable.

The spread of the disease can be limited with frequent hand washing and covering your mouth when coughing.

Those are all things students at Cary-Grove High School were being told, after 23 confirmed cases of whooping cough at that school.

The McHenry County Department of Health said the first confirmed cases of whooping cough came from Cary-Grove High School.

A school spokesperson said that, in addition to overnight school disinfection, high touch areas – like desks and door knobs – are receiving extra cleaning attention.

Hand sanitizers have been placed throughout the building, along with signs posted about the need for students to wash their hands frequently.

Cary-Grove, along with two Cary middle schools, Cary Junior High and Lundahl Middle, have all had confirmed whooping cough cases for a combined total of 26 in the area so far.

At Cary-Grove, parents have received two emails letting them know about the cases there and what they can do about it.

Cindy Baker said her daughter has been “taught to wash her hands and use hand sanitizer in between and, hopefully, not spread it any further than it is and have your normal hygiene. Cover your mouth when you cough and don’t spread your germs.”

Her daughter, freshman Emma Baker said “at lunch, like, all the lunch tables are, like, cleaned off I noticed more often now and, like, the desks are sometimes cleaned off, too.”

When it comes to stopping the spread of the infection, besides covering your mouth when you cough, those infected need to stay home for five days while taking their full course of antibiotics.

There are also two confirmed cases at Deer Path Elementary in Crystal Lake and one case at Martin Elementary in Lake in the Hills.