The student attended Ennis High School last year, where he took a science class from a teacher who has the contagious form of tuberculosis.
The school district and health department will begin administering skin tests on Tuesday to students who were in close contact with the student, including people who had class with him and his close friends.
The Denton Independent School District will notify high school parents by phone Thursday night if their child needs to be tested.
Melissa Sosa said she took her 16-year-old son to the hospital on Tuesday after he passed out. Skin tests for exposure to tuberculosis came back positive. They now are waiting on the results of another test to determine whether or not he has the contagious form of the disease, The Associated Press reported.
The Denton County Health Department said it is closely monitoring the situation.
Last month, more than 800 students were tested in Ennis after 100 tested positive for exposure to the bacterial infection.
Tuberculosis is caused by a bacteria that is spread from person to person through the air. It typically attacks the lungs but can also affect other organs, such as the brain, kidneys or spine. It can be fatal if not treated.
Symptoms include flu-like conditions including coughing, fever and weight loss.
Not everyone who is infected with tuberculosis gets sick. People can be exposed to it but not have active tuberculosis.
NBC 5's Julie Tam and Sara Story contributed to this report.