School officials and the Riverside County Department of Public Health said Tuesday they contacted the parents of students at Vista del Lago High School who may have come into contact with the former student, who last attended the school in late January.
According to health officials, the student was diagnosed with a contagious form of the airborne disease following a doctor's visit. About 700 students may have come in contact with the infected student.
The school will set up a testing site to screen students in April. Testing before then may not accurately show in test results.
"The goal is to let them know that even though this is a risk in terms of other students becoming infected, we want to test just as a precaution," said Barbara Cole, director of disease control at the Department of Public Health.
The disease is spread by breathing the same air as an infected person for a prolonged period. Tuberculosis is curable if caught early. Leaving the illness untreated can damage the lungs and other organs, and could be fatal.
Last year, Riverside County reported 68 cases of tuberculosis, but this is the first case of tuberculosis on a county school campus.