FARMINGTON — Regional School Unit 9 representatives are sending letters to students’ parents on what to do if they see signs of whooping cough in their children, Superintendent Tom Ward said Thursday.

The district has had 17 cases of whooping cough, which are being monitored, he said. The students were sent home, checked by their doctors and given antibiotics prior to returning to school, he said.

Some students who were suspected of having the highly-contagious bacterial infection were sent home and were checked by their doctors, he said. The students tested negative.

It has been mostly students at Mt. Blue Middle School and Cascade Brook School in Farmington, he said, but it is now starting to spread into other schools in the district.

Letters are going to parents of children in the other schools in the 10-town district.

There are no known cases of chicken pox that he is aware of, Ward said.

The first signs of whooping cough are sneezing, runny nose, fever and a cough, according to the Maine Center for Disease Control and Prevention website. After one or two weeks, the cough gets worse and occurs in sudden, uncontrollable bursts. The person may look blue in the face and have a hard time breathing. After a coughing spell, the person may throw up.

The disease can be serious, especially in infants. Many infants get it from older siblings, parents or caregivers, who might not even know they have the disease, the website states.

dperry@sunjournal.com