San Francisco health officials announced today that testing at Archbishop Riordan High School revealed 204 cases of latent tuberculosis infection among students and staff. The findings follow an outbreak of active tuberculosis cases at the private Catholic school, prompting widespread testing and a temporary shift to hybrid learning. While latent TB is not contagious, the discovery underscores the importance of proactive screening and treatment to prevent the disease from progressing to an active, transmissible form.
The San Francisco Department of Public Health (SFDPH) has been working closely with Archbishop Riordan since the first case of active tuberculosis was identified in a student in September 2025, with confirmation in November of the same year. Two additional active cases were confirmed in January 2026, leading to required testing for all students and staff. Of the 1,261 test results received, 219 were positive for tuberculosis, with 204 confirmed as latent TB infection. Chest X-rays are currently being conducted to rule out active disease in the remaining positive cases.
Understanding Latent vs. Active Tuberculosis
Tuberculosis is caused by bacteria that attack the lungs, but it can too affect other parts of the body. According to the Centers for Disease Control and Prevention (CDC), latent TB infection means a person has been infected with TB bacteria, but the bacteria are inactive and causing no symptoms. The CDC explains that people with latent TB cannot spread the infection to others. However, without treatment, there is a risk – approximately 5 percent over a lifetime – that the latent infection will progress to active TB disease.
Active TB disease, is contagious and can cause symptoms such as a persistent cough, fever, night sweats, and weight loss. In severe cases, the infection can spread beyond the lungs. Before the advent of antibiotics, tuberculosis was a leading cause of death in the United States.
Riordan High School Response and Return to In-Person Learning
Archbishop Riordan temporarily shifted to hybrid learning in early February as a precautionary measure during the testing and contact tracing process. However, the school has now cleared 99 percent of students and 100 percent of faculty and staff, allowing a full return to in-person instruction on Monday, February 23, 2026. This clearance was achieved using a TB protocol developed in collaboration with public health guidance.
As of February 20, 2026, three confirmed cases of active TB have been identified within the school community – one diagnosed in November 2025 and two more in January 2026 – and three additional cases are suspected. All confirmed and suspected active cases are currently undergoing treatment, and health officials state that We find no contagious cases on campus.
Public Health Perspective and Broader Implications
Dr. Susan Philip, San Francisco’s Health Officer, emphasized that “the risk to the general public remains low.” She highlighted the critical role of contact tracing and testing in preventing future active cases and protecting long-term health. Public health officials have confirmed that no related active TB cases have been reported at other San Francisco schools.
Dr. George Rutherford, a pediatrician and infectious disease specialist at UCSF, described the public health response as “thorough and appropriate.” He noted that San Francisco’s public health department is well-equipped to manage complex outbreaks. However, Rutherford also pointed out that the proportion of latent infections – 16 percent of those tested – is significant, exceeding typical background rates. “About 10 percent of people in the world have latent tuberculosis. In the United States, it’s lower — on the order of 6 percent in California,” Rutherford said. He suggested that the elevated rate at Riordan could indicate a clustering of cases within the school, potentially linked to specific activities or groups.
Rutherford cautioned that the significance of the 16 percent figure depends on the specifics of the testing process. He explained that pulmonary infections can be particularly transmissible in settings where forceful exhalation occurs, such as choir practice.
What to Expect Next
The SFDPH continues to monitor the situation at Archbishop Riordan and will provide updates as needed. Health officials are focused on ensuring that all individuals with latent TB infection receive appropriate treatment to prevent progression to active disease. The school is working closely with the health department to implement ongoing monitoring and prevention measures.
This outbreak serves as a reminder of the importance of TB screening, particularly in congregate settings. Individuals experiencing symptoms of active TB – a persistent cough, fever, night sweats, or unexplained weight loss – should seek medical attention promptly.
Disclaimer: This article provides general information about tuberculosis and should not be considered medical advice. Please consult with a healthcare professional for diagnosis and treatment of any health condition.
If you have questions or concerns about tuberculosis, please contact the San Francisco Department of Public Health or your healthcare provider. Share this information with your community to help raise awareness about TB prevention and control.
