San Diego County health authorities say a person at Vista High School was diagnosed with tuberculosis and may have exposed students and staff.
The health agency says in a press release Wednesday that it is working with the Vista Unified School District to notify those who were potentially exposed between Aug. 20 and Oct. 30.
Free testing is planned at the school on Dec. 18.
County health officer Dr. Wilma Wooten says TB usually requires many hours of close, indoor contact to spread to others, so most people who are exposed in classrooms do not develop the disease.
The health agency says TB is not uncommon in the San Diego region.
There have been 211 cases reported in 2012 and 263 cases last year.