Additional Coverage:
Tuberculosis Outbreak Reported at San Francisco High School
SAN FRANCISCO, CA – The San Francisco Department of Public Health (SFDPH) has issued a health advisory concerning a tuberculosis (TB) outbreak linked to Archbishop Riordan High School. As of January 29, three active cases of TB have been diagnosed among individuals associated with the school since November 2025, alongside over 50 identified latent TB infections within the school community.
TB is a treatable bacterial infection primarily affecting the lungs, though it can also impact other organs. It is an airborne contagion, spread through actions such as coughing, sneezing, or saliva. While latent TB infections are not contagious, the bacteria are inactive in the body and can develop into active disease in 5% to 10% of cases.
The SFDPH advisory emphasizes that efforts are underway to provide preventive treatment for all affected individuals. Students and staff at Archbishop Riordan High School have been instructed to remain home if unwell and to obtain medical clearance before returning. Furthermore, all students and staff, regardless of symptoms, are required to undergo TB evaluation, with repeat assessments mandated every eight weeks until the outbreak is resolved.
Health officials state that the risk to the general population remains low, and therefore, these extensive measures are not deemed necessary for individuals not connected to the Archbishop Riordan High School outbreak.
In the United States, over 565 people succumbed to TB in the most recent year of available data, according to the Centers for Disease Control and Prevention (CDC). San Francisco has reported a case fatality rate exceeding 10%.
Approximately 25% of individuals are estimated to have been infected with the TB bacteria, but only 5% to 10% will develop symptoms and the active disease. Only those with active symptoms are contagious.
Symptoms can be mild and include coughing, chest pain, fatigue, weight loss, weakness, fever, and night sweats. In more severe instances, patients may cough up blood.
Masae Kawamura, M.D., a former TB control director in San Francisco, notes that initial symptoms are often minimal and can be mistaken for allergies, smoking-related coughs, or persistent colds.
Beyond the lungs, TB can affect the kidneys, spine, skin, and brain. Dr. Kawamura stresses that TB can affect any organ, but its prevalence in the lungs (over 80% of cases) is particularly dangerous due to the airborne spread mechanism via coughing.
TB is diagnosed through rapid diagnostic tests and typically treated with a daily course of antibiotics for four to six months. Common medications include isoniazid, rifampicin, pyrazinamide, and ethambutol. Incomplete adherence to the medication regimen can lead to drug-resistant bacteria, necessitating alternative treatments.
Untreated TB is fatal in approximately half of its victims, with about 25% recovering spontaneously and another 25% developing chronic active TB, according to Dr. Kawamura.
She describes TB as a “social disease of crowding and mobility,” highlighting that anyone who breathes is at risk. Congregate settings such as hospitals, nursing homes, prisons, schools, and homeless shelters are particularly susceptible to easier spread, especially when multiple risk factors are present.
Individuals at higher risk of developing TB disease after exposure include those with diabetes, weakened immune systems, malnutrition, tobacco use, and excessive alcohol consumption. Babies and young children also face an elevated risk. The most effective prevention strategy involves testing at-risk individuals and treating latent tuberculosis infection.
Archbishop Riordan High School has been contacted for comment regarding the outbreak.