Public health officials are looking into a single case of tuberculosis reported at Pierre Elliott Trudeau High School in Markham late last week.
It is not yet known whether it is a student or a staff member who has the contagious disease.
People who were in contact with the affected person are being tested, said York Region's Associate Medical Officer of Health Lilian Yuan.
"On average, York Region gets around 60 cases of TB a year," Yuan added. "So far, there's been 22 cases across York Region this year."
According to officials, people who were in contact with the affected person are being tested.
York Region Public Health also stresses that the risk of some else contracting the disease is very low.
Calls from concerned parents and students are being referred to public health officials, said York Region District School Board spokesperson Licinio Miguelo.
He added that letters alerting families to the situation were sent home with students and an information session was held on Monday.
Concerned community members are encouraged to contact York Region Health Connection at 1-800-361-5653.
