Eastern Health says the case of tuberculosis was confirmed in a student attending Leary's Brook Junior High School.
Health and school officials are trying to identify students who may have been in contact with the youth, particularly those in one of the school's Grade 9 classes.
Dr. David Allison, the medical officer of health for Eastern Health, says the risk of contracting tuberculosis is very low even among students who had close contact with the youth.
Tuberculosis is a disease caused by bacteria and symptoms may include a cough that lasts for two or more weeks, chest pain, loss of appetite and fever.
Treatment normally involves taking medication for a period of six to 12 months.