VISTA, Calif. — Students and staff at Vista High School may have been exposed to tuberculosis, , the San Diego County Health and Human Services Agency reported Wednesday.

The agency said that someone at the school was diagnosed with the highly contagious respiratory disease and may have infected people at the school between Aug. 20 and Oct. 30

The HHSA is working to notify those who might have been exposed by the unidentified carrier and has scheduled a free testing clinic at the campus on Dec. 18.

“Symptoms of active TB include persistent cough, fever, night sweats and unexplained weight loss,” said Dr. Wilma Wooten, the county’s public health officer. “TB usually requires many hours of close, indoor contact to spread to others, so most people who are exposed in classrooms do not get infected or develop the disease.”

The illness is treatable with medication.

HHSA officials said 211 cases of TB have been reported in the region in 2012, compared to 263 last year.