What to know about tuberculosis in the Bay Area after outbreak at high school

The San Francisco Public Health Department has launched a “large-scale TB contact investigation” after a tuberculosis outbreak this week at Archbishop Riordan High School infected at least three students, prompting administrators to cancel classes and basketball games in an attempt to stop its spread.

In addition to the three active cases, public health officials have identified at least 30 latent TB infections — cases in which people carry the bacteria but are not contagious — though experts...