Tuberculosis Outbreak Hits San Francisco High School

204 latent TB cases found among students and staff at Archbishop Riordan High

Feb. 21, 2026 at 8:22pm by Ben Kaplan

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A recent outbreak of tuberculosis (TB) at Archbishop Riordan High School in San Francisco has led to the discovery of 204 cases of latent TB among students and staff. While the immediate risk to the general public remains low, the incident raises concerns about potential trends in TB transmission and the need for robust public health preparedness.

Why it matters

The Riordan outbreak highlights the ongoing challenges in controlling the spread of tuberculosis, a disease that was once a leading cause of death in the U.S. but has seen a resurgence in recent years. Factors like disruptions to healthcare, social determinants of health, increased travel, and weakened immunity may be contributing to the rise in TB cases, underscoring the importance of vigilance and investment in public health infrastructure.

The details

The San Francisco Department of Public Health (SFDPH) began investigating after identifying three cases of active TB at the school since November 2025. Subsequent testing of students and staff revealed 219 positive results for tuberculosis, with 204 confirmed as latent TB – approximately 16% of those tested. Chest X-rays are being conducted to rule out active disease in the remaining positive cases.

  • The SFDPH investigation began in November 2025 after three cases of active TB were identified at the school.
  • As of February 20, 2026, three confirmed cases of active TB and three suspected cases have been identified within the school community.

The players

San Francisco Department of Public Health (SFDPH)

The local public health agency responsible for investigating the tuberculosis outbreak at Archbishop Riordan High School and coordinating the response.

Dr. George Rutherford

A pediatrician and infectious disease specialist at the University of California, San Francisco (UCSF) who provided expert analysis on the significance of the high rate of latent TB infections found at the school.

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What they’re saying

“The proportion of latent infections is significant. The rate is higher than typically seen in the general population, where latent TB prevalence is around 6% in California and approximately 10% globally.”

— Dr. George Rutherford, Pediatrician and Infectious Disease Specialist, UCSF

What’s next

The health department reports that there are no currently contagious cases on the Riordan High School campus, and the school has returned to in-person instruction after implementing a TB clearance protocol.

The takeaway

This outbreak serves as a critical reminder of the ongoing need for vigilance and investment in public health infrastructure to prevent and control the spread of tuberculosis. Continued monitoring, research, and proactive measures are essential to protect communities from this potentially serious disease.