Tuberculosis outbreak reported at Catholic high school in Bay Area. Cases statewide are climbing

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 have been canceled and will resume Feb. 9, with temporary hybrid learning to take 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 is 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 will 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 CDC estimated up to 13 million people nationwide live with latent TB.

How does California’s TB rate compare to the country?

Public health officials report 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 total cases reported in 2019, according to the CDPH.

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 between 2020 and 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 lay dormant in the body for decades, and if identified, treatment could stop the illness from ever 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 have visited 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 required 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 affect other parts of the body such as the brain, kidneys or spine, according to the Centers for Disease Control and Prevention. If not treated properly, TB disease 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, the germs 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 longerChest painCoughing up blood or phlegm Weakness or fatigueWeight loss Loss of appetiteChills Fever Night sweatsGenerally, who is at risk of contracting TB?

Those at 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 a higher 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.

Persons 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 risk of contracting the disease include babies and young children.