Tuberculosis Is Making a Comeback in the U.S.

Tuberculosis has likely reclaimed its spot as the world’s deadliest infectious disease. A new report from the Centers for Disease Control and Prevention shows that cases of TB, a bacterial infection, once again rose in the U.S. in 2023, reaching a toll not seen for a decade. While its incidence remains low in the U.S., TB has recently become more common across the globe.

The latest status update on TB came last week in the CDC’s Morbidity and Mortality Weekly Report. In 2023, there were 9,615 documented cases of TB within the U.S., up from 8,320 reported in 2022 and the highest tally since 2013. This increase was found among both U.S. born and non-U.S. born residents, though the risk of TB is generally higher in the latter group.

TB is caused by Mycobacterium tuberculosis. It spreads between people through the air and typically affects the lungs, though the bacteria can reach other parts of the body. Acute cases of TB usually result in respiratory symptoms like chest pains, chills, and coughing up blood. But the infection also often becomes latent, not causing illness until years later when the immune system is weakened for another reason, such as HIV infection.

For years, the U.S. has had one of the lowest TB rates in the world, aided by programs that try to identify and quickly treat people who either have active TB or are carrying latent TB that could someday reactivate. As a result, the U.S. experienced ever-lowering cases of TB for 27 years, with an especially substantial drop in 2020. But this sharp drop was largely caused by the disruptions of the covid-19 pandemic on existing TB programs, which led to reduced testing, diagnosis, and treatment. The after-effects of the pandemic have contributed to TB’s resurgence ever since, with 2023 being the third straight year of increased cases.

The report authors note that TB is not a serious threat to most Americans, and about 85% of reported cases in the U.S. come from the bacteria reactivating in someone who has carried it for a while, not from recently caught infections, so the danger of sustained outbreaks is low as well. But TB has been on the rise globally. A report from the World Health Organization last November estimated that there were 10.6 million cases of active TB in 2022, including 7.5 million newly diagnosed cases, the highest seen since the WHO began tracking TB globally.

There has been progress on some fronts: Global deaths from TB declined from 1.6 million in 2021 to 1.3 million in 2022, for instance, showing that more people are getting timely treatment. And the estimated gap between reported and actual new cases of TB is thought to have shrunk back to pre-pandemic levels. But given the drop in reported deaths from covid-19 last year, it’s almost certain that TB has once again become the largest cause of death from a single germ. Getting rid of TB in the U.S. and worldwide is still very possible, but it will take plenty of effort, the CDC authors say.

“Renewed progress toward TB elimination will require strong public health systems both domestically and globally that are responsive to health disparities, capable of maintaining essential disease prevention and control activities, and prepared to withstand the next pandemic or other large-scale crisis,” they wrote.