Fifty students and staffers have become sick with a gastrointestinal illness at three Boston schools.

The schools affected are Up Academy Holland School in Dorchester, where 18 students and four staff members became sick, Up Academy Dorchester School, where 13 students and three staff became sick, and Young Achievers K-8 School in Mattapan, where 12 students became sick, according to the Boston Public Schools.

“The Boston Public Health Commission (BPHC) has been notified of the illnesses, and had conducted inspections of the buildings, along with the BPS Facilities Department, which is thoroughly cleaning the facilities to prevent transmission of any illnesses as a precautionary measure,’’ according to the statement.


Commission spokeswoman Che Knight said the agency cannot confirm the illness is norovirus, but said it’s likely.

“Based on the cluster of symptoms and the progression of it, we think that’s what it is,’’ said Knight.

The schools are notifying families at the schools about the illnesses and providing information about how to prevent transmission of it, the statement said.

“Parents are urged to keep their children home from school if they show any symptoms of stomach-related illnesses,’’ the statement said.

Norovirus is found in the stool or vomit of infected people, according to the Boston Public Health Commission. People become infected by eating food or drinking liquids contaminated by an infected person or touching contaminated surfaces. Symptoms include nausea, diarrhea, vomiting, and stomach pain, and sometimes fever. It usually lasts one to two days after exposure, Knight said.

“Around this time of year, we usually see an uptick in gastrointestinal illness,’’ said Knight. “And this year is no different.’’