Tuberculosis cases hit a 12-year high in California. What to know

California is outpacing much of the rest of the nation in cases of tuberculosis, according to the federal Centers for Disease Control and Prevention.

In 2025, California had 5.5 tuberculosis cases per 100,000 people on average, according to the CDC’s latest provisional tuberculosis data report, released in March.

That’s the highest rate the state has reported in 12 years, the CDC said.

As a whole, the United States saw an average of three TB cases per every 100,000 people in 2025, according to federal data.

Here’s what to know about the highly contagious lung disease:

What is tuberculosis?

Tuberculosis is a disease caused by bacteria that usually attack the lungs.

Although rare, the disease can be deadly if left untreated.

TB was once considered “an ancient scourge,” according to Science Direct, leading to epidemics in Europe and North America during the 18th and 19th centuries.

An outbreak in January among high school students in San Francisco points to the persistence of the disease, which has both active and latent stages, according to previous reporting by The Mercury News.

How common is tuberculosis?

Most people in the United States are at low risk for tuberculosis, the CDC said, and TB rates in the nation are lower than in developing countries.

In California, 2,150 people were diagnosed with TB in 2025, an increase of 41 cases from the previous year, according to the CDC.

The TB rate among people born outside the United States was 12 times higher than the rate among people born in the United States, according to the California Department of Public Health.

Tuberculosis case rates were highest among people born in the Philippines, Vietnam, India, China and Mexico, the state health agency said.

What are common symptoms of tuberculosis?

According to the CDC, common symptoms of active tuberculosis are cough, chest pain and coughing up blood.

Other symptoms can include:

• Weight loss
• Loss of appetite
• Chills
• Fever
• Sweating at night

Does TB only affect your lungs?

Tuberculosis usually affects the lungs, the CDC said.

“TB can also affect other parts of the body, such as the brain, the kidneys or the spine,” the federal agency said.

TB can also affect multiple parts of the body at the same time, such as lungs and lymph nodes.

How does contagious disease spread?

TB is spread through the air from one person to another by coughing, even speaking or singing, the California Department of Public Health said.

When should I see a doctor about tuberculosis?

The American Lung Association recommends seeing a doctor if you have symptoms of active TB disease, were exposed to someone who has active TB or are at higher risk of developing the disease.

You should also consult a physician if you have heath screening requirements for work, school or travel.

Who’s at the highest risk of getting TB?

Anyone can get tuberculosis, but those at higher risk of contracting TB include people with compromised immune systems, according to previous reporting by The Sacramento Bee.

You could also be at a higher risk if:

• You were born or frequently travel to countries where tuberculosis is common.
• Live or used to live in large group settings where TB is more common, such as jails or homeless shelters.
• Recently spent time with someone who has active TB
• Work in places where TB is more likely to spread.

A tuberculosis vaccine is being developed by Johns Hopkins Medicine, The Bee previously reported.

Can you test for TB?

Two types of tests are available for tuberculosis infections: a blood test and a skin test.

A positive test result for infection means you have TB germs in your body.

If you test positive, a healthcare provider will do other tests to determine if you have inactive TB, also known as a latent TB infection, or active TB disease, according to the CDC.

How is tuberculosis treated?

Both inactive tuberculosis and active TB can be treated with a mix of several different medicines. Treatment can take four to nine months, the health agencies stated.

Without treatment, people with inactive TB can develop active TB disease at any time and become sick.

This story was originally published May 7, 2026 at 11:09 AM.