Tuberculosis Outbreak Linked to San Francisco High School, Health Officials Report

An outbreak of tuberculosis (TB) has been confirmed at Archbishop Riordan High School in San Francisco, prompting public health officials to issue a health advisory and implement comprehensive testing measures for the school community.

The San Francisco Department of Public Health (SFDPH) reported three active TB cases associated with the school since November 2025. Over 50 latent TB infections have also been identified among students and staff, according to the January 29 advisory.

While individuals with latent TB infections are not contagious, health officials note that 5-10% of these cases can progress to active, transmissible disease if left untreated. This progression risk has triggered an aggressive response from health authorities.

“Efforts are underway to assure preventive treatment for all these individuals,” the SFDPH stated in its advisory. School officials have instructed all staff and students to remain home if they exhibit any symptoms and to obtain medical clearance before returning to campus.

The health department has mandated TB evaluations for everyone affiliated with the school, regardless of whether they show symptoms. These assessments will continue every eight weeks until the outbreak is declared resolved. Health officials emphasized that the risk to the general public remains low.

Tuberculosis is an airborne bacterial infection primarily affecting the lungs, though it can spread to other organs including the kidneys, spine, brain, and skin. It transmits through respiratory droplets when infected individuals cough, sneeze, or even speak.

“If you breathe, you can catch TB — so all people are at risk,” said Dr. Masae Kawamura, a former TB control director in San Francisco and tuberculosis clinician who serves on the board of directors of global public health organization Vital Strategies.

TB presents particular dangers in congregate settings like schools, where prolonged indoor contact facilitates transmission. San Francisco’s case fatality rate exceeds 10%, significantly higher than many other communicable diseases.

The Centers for Disease Control and Prevention reports that more than 565 people died from TB in the most recent complete year of available data nationwide. Without proper treatment, TB proves fatal in approximately half of cases, while about 25% recover spontaneously and the remaining 25% develop chronic active infections, according to Dr. Kawamura.

TB symptoms can be subtle initially, often resembling common respiratory ailments. Those with active TB typically experience persistent coughing, chest pain, fatigue, weight loss, weakness, fever, and night sweats. In advanced cases, patients may cough up blood.

“Often, there are minimal symptoms for a long time and people mistake their occasional cough with allergies, smoking or a cold they can’t shake off,” Dr. Kawamura explained.

Diagnosis involves rapid testing, and treatment consists of a four to six-month regimen of antibiotics, including isoniazid, rifampicin, pyrazinamide, and ethambutol. Completing the full course of medication is crucial, as premature discontinuation can lead to drug-resistant TB strains that require alternative treatments.

Those at highest risk for TB progression after exposure include individuals with diabetes, compromised immune systems, malnutrition, tobacco users, and those who consume excessive alcohol. Infants and children also face elevated risks.

Health experts emphasize that proactive testing of high-risk populations and treating latent infections represent the most effective prevention strategies. While approximately 25% of people worldwide have likely been infected with TB bacteria, only a small percentage develop active, symptomatic disease.

The SFDPH continues to monitor the situation closely, working with school administrators to contain the outbreak and prevent further transmission within the educational community.