Department of Research & Evaluation News

People born in countries with a high burden of tuberculosis (TB) and living in the United States have higher rates of TB disease, and may need more focused screening, according to new Kaiser Permanente research. The study also found higher rates of TB among patients with certain high-risk medical conditions.

The study was published in Open Forum Infectious Diseases in March 2025.

The study is the largest community-based analysis of TB, including more than 4.7 million adult members of Kaiser Permanente Northern California from 2003 to 2022. The analysis identified 1,463 people with active TB disease; 61% of them were born in countries with endemic TB disease.

“This study provides the most contemporary view we have of the progression of tuberculosis, something that Kaiser Permanente is uniquely equipped to provide,” said the study’s senior author,  Sara Y. Tartof, PhD, MPH, an epidemiologist with the Kaiser Permanente Southern California Department of Research & Evaluation. “Not only does our Kaiser Permanente membership include many people who were born outside of the U.S., but our members usually stay with us for more than a decade, which greatly facilitates tuberculosis research.”

Findings have potential to guide screenings

The findings can guide screening and treatment efforts, said lead author Jacek Skarbinski, MD, a research scientist with the Kaiser Permanente Division of Research and an infectious diseases physician with The Permanente Medical Group.

“We set out to quantify the TB incidence in a large, diverse group of people in the U.S., and to identify risk factors for developing the disease,” said Dr. Skarbinski. “Our findings are important because they look at all previously identified risk factors for TB disease in one very large cohort. They help us focus our screening resources on our highest risk patients.”

On average, those with TB disease were more likely to be older (average age 51), male, Asian, born in a TB-endemic country, and have a high or intermediate risk health condition. The analysis was not able to identify where 48.5% of the people were born; this group represented 19% of all persons with TB disease.

Risk of TB higher for those born outside U.S.

Risk of TB disease was 15 times higher among people born in a TB-endemic country compared with those born in the U.S. People born in Ethiopia, Burma, Philippines, and Vietnam had highest incidence of TB disease. Overall, risk of TB was higher in those born in Africa, East Asia, South Asia, and Southeast Asia. Of the 4.7 million people studied, 12.3% were born in a TB-endemic country.

The comorbid conditions studied included HIV infection, leukemia and lymphoma, diabetes, end-stage renal disease, and use of corticosteroids or other immunosuppressants. These medical risk factors were chosen because they are well known to be associated with increased risk of active TB. The increased risks ranged from 39% for corticosteroids to 377% for HIV.

The combination of being born in a country with endemic TB and having a high-risk medical condition was particularly striking; 79% of TB cases in people with those health factors were from a country with endemic TB.

“TB is a top infectious disease, and major cause of death in the world,” Dr. Skarbinski said. “While it’s relatively rare in the U.S., TB is completely preventable. We really need to improve our efforts to prevent TB disease here through screening and treatment of latent TB infection.”

Latent TB can develop into active disease

A person with latent TB may not have symptoms and the infection is not transmissible. Latent disease can develop into active disease, which can be passed to others, and may or may not have symptoms.

Most cases of active disease are among people who have lived with a latent infection. Both latent and active disease can be treated with antibiotics. There is no vaccination to prevent TB.

The U.S. Preventive Services Task Force recommends testing and treatment of populations at higher TB infection risk, including non-U.S.-born people.

Findings important to understanding TB

Few studies have identified risk of TB, and medical risk factors, in a single large general population study in the U.S., the authors said. “These data are critical for primary care providers and health systems to understand TB disease risk for patients in primary care settings,” they wrote.

The study was funded by the National Institutes of Health and the Physician Researcher Program of The Permanente Medical Group Delivery Science and Applied Research Program.

Additional co-authors were Yuching Ni, MS, Nicole Halmer, Joshua R. Nugent, PhD, and Laura B. Amsden, MPH, of the Division of Research; Katia J. Bruxvoort, PhD,  Heidi Fischer, PhD, Lei Qian, PhD, Sally F. Shaw, DrPH, and Brigitte Spence of the Department of Research & Evaluation; and Bradley K. Ackerson, MD, of the Southern California Permanente Medical Group.