Public health officials in Northern California are investigating a tuberculosis outbreak, identifying more than 50 cases at a private Catholic high school and ordering those who are infected to stay home. The outbreak comes as tuberculosis cases have been on the rise statewide since 2023.
The San Francisco Department of Public Health issued a health advisory last week after identifying three active cases and 50 latent cases of tuberculosis at Archbishop Riordan High School in San Francisco. The disease attacks the lungs and remains in the body for years before becoming potentially deadly.
A person with active TB can develop symptoms and is infectious; a person with a latent tuberculosis infection cannot spread the bacteria to others and doesn’t feel sick. However, a person with a latent TB infection is at risk of developing the disease anytime.
The three cases of active TB have been diagnosed at the school since November, according to public health officials. The additional cases of latent TB have been identified in people within the school community.
Archbishop Riordan High School, which recently transitioned from 70 years of exclusively admitting male students to becoming co-ed in 2020, did not immediately respond to the The Times’ request for comment.
School officials told NBC Bay Area news that in-person classes had been canceled and would resume Feb. 9, with hybrid learning in place until Feb. 20. Students who test negative for tuberculosis will be allowed to return to campus even after hybrid learning commences.
Officials with the San Francisco Department of Public Health said the risk to the general population was low. Health officials are currently focused on the high school community.
How serious is a TB diagnosis?
Active TB disease is treatable and curable with appropriate antibiotics if it is identified promptly; some cases require hospitalization. But the percentage of people who have died from the disease is increasing significantly, officials said.
In 2010, 8.4% of Californians with TB died, according to the California Department of Public Health. In 2022, 14% of people in the state with TB died, the highest rate since 1995. Of those who died, 22% died before receiving TB treatment.
The Centers for Disease Control and Prevention estimated that up to 13 million people nationwide live with latent TB.
How does California’s TB rate compare to the country?
Public health officials reported that California’s annual TB incidence rate was 5.4 cases per 100,000 people last year, nearly double the national incidence rate of 3.0 per 100,000 in 2023.
In 2024, 2,109 California residents were reported to have TB compared to 2,114 in 2023 — the latter was about the same as the total number of cases reported in 2019, according to the state Department of Public Health.
The number of TB cases in the state has remained consistent from 2,000 to 2,200 cases since 2012, except during the COVID-19 pandemic from 2020 to 2022.
California’s high TB rates could be caused by a large portion of the population traveling to areas where TB is endemic, said Dr. Shruti Gohil, associate medical director for UCI Health Epidemiology and Infection Prevention.
Nationally, the rates of TB cases have increased in the years following the COVID-19 pandemic, which “was in some ways anticipated,” said Gohil. The increasing number of TB cases nationwide could be due to a disruption in routine care during the pandemic and a boom in travel post-pandemic.
Routine screening is vital in catching latent TB, which can lie dormant in the body for decades. If the illness is identified, treatment could stop it from becoming active. This type of routine screening wasn’t accessible during the pandemic, when healthcare was limited to emergency or essential visits only, Gohil said.
When pandemic restrictions on travel were lifted, people started to travel again and visit areas where TB is endemic, including Asia, Europe and South America, she said.
To address the uptick in cases and suppress spread, Gov. Gavin Newsom signed Assembly Bill 2132 into law in 2024, which requires adult patients receiving primary care services to be offered tuberculosis screening if risk factors are identified. The law went into effect in 2025.
What is TB?
In the United States, tuberculosis is caused by a germ called Mycobacterium tuberculosis, which primarily affects the lungs and can impact other parts of the body such as the brain, kidneys and spine, according to the Centers for Disease Control and Prevention. If not treated properly, TB can be fatal.
TB is spread through the air when an infected person speaks, coughs or sings and a nearby person breathes in the germs.
When a person breathes in the TB germs, they settle in the lungs and can spread through the blood to other parts of the body.
The symptoms of active TB include:
- A cough that lasts three weeks or longer
- Chest pain
- Coughing up blood or phlegm
- Weakness or fatigue
- Weight loss
- Loss of appetite
- Chills
- Fever
- Night sweats
Generally, who is at risk of contracting TB?
Those at higher risk of contracting TB are people who have traveled outside the United States to places where TB rates are high including Asia, the Middle East, Africa, Eastern Europe and Latin America.
A person has an increased risk of getting TB if they live or work in such locations as hospitals, homeless shelters, correctional facilities and nursing homes, according to the CDC.
People with weakened immune systems caused by health conditions that include HIV infection, diabetes, silicosis and severe kidney disease have a higher risk of getting TB.
Others at higher risk of contracting the disease include babies and young children.
