An outbreak of tuberculosis at a San Francisco high school has led health officials to mandate testing for all students and staff following three active cases and over 50 latent infections.
An outbreak of tuberculosis (TB) has been confirmed at Archbishop Riordan High School in San Francisco, prompting health officials to take immediate action. The San Francisco Department of Public Health (SFDPH) issued a health advisory on January 29, detailing the situation and the necessary steps for the school community.
According to the advisory, three active TB cases have been diagnosed among individuals associated with the school since November 2025. In addition, over 50 latent TB infections have been identified within the school community. TB is a bacterial infection primarily affecting the lungs, but it can also impact other organs. It is an airborne disease, transmitted through coughing, sneezing, or saliva.
A person with a latent TB infection carries the bacteria, but it remains inactive in their body. While latent TB is not contagious, it can progress to active disease in approximately 5% to 10% of cases. The SFDPH has stated that efforts are underway to ensure preventive treatment for all affected individuals.
Staff and students at Archbishop Riordan High School have been advised to stay home if they are feeling unwell and to seek medical clearance from a healthcare provider before returning to school. Furthermore, TB evaluations are required for all students and staff, regardless of whether they exhibit symptoms. Health officials have indicated that repeat TB assessments will be necessary every eight weeks until the outbreak is resolved.
Currently, the risk to the general population is considered low, and therefore, the measures are not required for individuals not connected to the outbreak at Archbishop Riordan High School. According to the Centers for Disease Control and Prevention (CDC), more than 565 people died from TB in the most recent year for which data is available. In San Francisco, health officials report a case fatality rate exceeding 10%.
While it is estimated that around 25% of the population may have been infected with the TB bacteria, only 5% to 10% will develop symptoms and become contagious. Symptoms of active TB can include a persistent cough, chest pain, fatigue, weight loss, weakness, fever, and night sweats. TB can also affect organs beyond the lungs, including the kidneys, spine, skin, and brain.
Dr. Masae Kawamura, a former TB control director in San Francisco and a tuberculosis clinician, emphasized the dangers of TB, stating, “TB can affect any organ of the body, but it causes disease in the lung in over 80% of cases. This is dangerous because it causes cough, the mechanism of airborne spread.” In severe cases, patients may cough up blood.
Dr. Kawamura noted that many individuals may experience minimal symptoms for an extended period, often mistaking their occasional cough for allergies, smoking, or a lingering cold. TB can be diagnosed through rapid testing, and treatment typically involves a regimen of antibiotics taken daily for four to six months. Common antibiotics include isoniazid, rifampicin, pyrazinamide, and ethambutol.
Failure to complete the prescribed course of antibiotics can lead to drug-resistant strains of TB, necessitating alternative treatments. If left untreated, TB can be fatal in about half of its cases. Dr. Kawamura explained that approximately 25% of individuals may recover on their own, while another 25% may develop chronic active TB.
“If you breathe, you can catch TB — so all people are at risk,” Dr. Kawamura stated, describing TB as a “social disease of crowding and mobility.” She added that congregate settings such as hospitals, nursing homes, prisons, classrooms, and homeless shelters are particularly susceptible to outbreaks, especially when multiple risk factors are present.
Those at the highest risk of developing TB disease after exposure include individuals with diabetes, weakened immune systems, malnutrition, tobacco use, and excessive alcohol consumption. Babies and children are also at increased risk.
The best preventive measure is to test those at risk and treat latent TB infections, according to health experts. The SFDPH continues to monitor the situation closely and has reached out to Archbishop Riordan High School for further comment.
For more information on tuberculosis and its prevention, visit the CDC’s website.
According to Fox News, health officials are taking proactive steps to manage the outbreak and protect the school community.