An outbreak of tuberculosis (TB) has been linked to a San Francisco high school.
The San Francisco Department of Public Health (SFDPH) issued a health advisory on Jan. 29 about the outbreak, which has been tied to Archbishop Riordan High School.
TB is a curable bacterial infection that targets the lungs, but can also infect other organs, according to Johns Hopkins. It is an airborne contagion that can be spread through coughing, sneezing or saliva.
Three active TB cases have been diagnosed among people associated with Archbishop Riordan High School since November 2025, according to the advisory, and over 50 latent TB infections have been identified within the school community.
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A person with a latent infection has been infected with the tuberculosis bacteria, but the bacteria are inactive in the body.
While latent-stage TB is not contagious, it can develop into active disease in 5% to 10% of people.
“Efforts are underway to assure preventive treatment for all these individuals,” the advisory states.
The school’s staff and students have been instructed to stay home if they are sick and to get medical clearance from a doctor before returning.
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“Additionally, TB evaluation is required for all students and staff affiliated with the school, regardless of symptoms,” the advisory stated. “Repeat TB assessment will be required every eight weeks until the outbreak is resolved.”
“At this time, risk to the general population is low, so these measures are not needed for patients who are not connected to the AHRS outbreak.”
In the U.S., more than 565 people died from TB in the most recent complete year of official data available, according to the Centers for Disease Control and Prevention.
There is a greater than 10% case fatality rate in San Francisco, per health officials.
While around 25% of people have likely been infected with the TB bacteria, just 5% to 10% will experience symptoms and develop the disease. Only people with symptoms are contagious.
Those who get sick with TB may experience mild symptoms, including coughing, chest pain, fatigue, weight loss, weakness, fever and night sweats, according to the CDC.
In addition to the lungs, the disease can also affect the kidneys, spine, skin and brain.
“TB can affect any organ of the body, but it causes disease in the lung in over 80% of cases,” Masae Kawamura, M.D., a former TB control director in San Francisco and a tuberculosis clinician, previously told Fox News Digital. “This is dangerous because it causes cough, the mechanism of airborne spread.”
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In more severe cases, patients may cough up blood, noted Kawamura, who serves on the board of directors of Vital Strategies, a global public health organization.
“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,” she added.
TB can be identified with rapid diagnostic tests. The disease is treated with antibiotics that are taken every day for four to six months, the CDC states. Some of the most common include isoniazid, rifampicin, pyrazinamide and ethambutol.
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Failing to take the complete course of medications can cause the bacteria to become drug-resistant, which would then require treatment with different medications.
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If TB goes untreated, it is fatal in about half of its victims, according to Kawamura. “About 25% recover on their own and another 25% persist as chronic active TB cases,” she said.
“If you breathe, you can catch TB — so all people are at risk,” said Kawamura, who calls TB a “social disease of crowding and mobility.”
“Since TB is airborne, congregate settings like hospitals, nursing homes, prisons, jails, classrooms and homeless shelters are places TB is more easily spread, especially if multiple risks are involved,” she added.
Those at the highest risk of developing TB disease after exposure include people who have diabetes, have weakened immunity, are malnourished, use tobacco and/or drink excess amounts of alcohol. Babies and children are also at higher risk.
The best means of prevention is testing those at risk and treating latent tuberculosis infection, according to the doctor.
Fox News Digital reached out to Archbishop Riordan High School requesting comment.
