Why tuberculosis cases have risen in recent years after decades of decline

After declining for nearly three decades, tuberculosis cases in the U.S. ticked up each year from 2020 to 2022.

Cases rose more than 15% in that time, though the disease is still less prevalent than it was before the pandemic. The Centers for Disease Control and Prevention recorded 8,300 tuberculosis cases last year, compared to nearly 8,900 in 2019.

Doctors who treat tuberculosis patients blame the pandemic for the rise in cases, since reduced access to medical care may have prevented some infections from being identified or delayed diagnoses long enough for a latent infection to progress to active disease.

"The number of tests done for TB dropped across the board in this country because everyone was busy looking for Covid," said Richard Chaisson, director of the Johns Hopkins University Center for Tuberculosis Research.

As a result, some newer cases of active tuberculosis could have been avoided, Chaisson said.

Last week, a Maryland high school reported a new case, and a woman with tuberculosis in Washington has garnered attention since January because she has refused numerous orders to isolate or receive treatment.

Other pandemic-related factors may also have hindered the disease's spread, according to Dr. Priya Shete, an associate professor of medicine and epidemiology at the University of California, San Francisco.

Shete said it's possible that some "public health measures that protected our communities from Covid also kept people from transmitting TB."

Travel restrictions may have also limited transmission temporarily, Chaisson added.

Identifying asymptomatic tuberculosis infections

Tuberculosis is caused by bacteria that can spread through the air when a person with an active case coughs, sneezes or speaks. Symptoms include a bad cough that lasts three weeks or longer, chest pain, or coughing up blood or phlegm, according to the CDC.

But up to 13 million people in the U.S. have latent infections, meaning the bacteria is inactive and the host isn’t contagious and doesn’t have symptoms. Around 5% to 10% of those latent cases, if left untreated, will develop into active disease.

The uptick in cases since 2020, though likely a blip in the overall downward trend, is a reminder of how important tuberculosis screenings are, according to Dr. Luke Davis, an associate professor of epidemiology and medicine at the Yale School of Public Health.

"If we could just get everyone who’s at risk screened once, that would be a huge public health victory," he said.

The U.S. Preventive Services Task Force, an independent panel of disease experts, on Tuesday released its latest set of screening guidelines for tuberculosis. The recommendations are the same as the previous 2016 guidance: Groups at increased risk — including those in homeless shelters or correctional facilities and people who were born or previously lived in countries with a high prevalence of tuberculosis — should be screened for latent infections.

Davis said the recommendations are primarily a way to encourage screenings and prompt insurance providers to cover the costs.

But right now, Shete said, Medicare and Medicaid do not pay for screenings for latent tuberculosis.

To screen for tuberculosis, doctors either administer a skin or blood test, though the latter is more common. The task force's recommendations don't specify how often people should be screened but note that it's reasonable to screen annually if a person is at continued risk of exposure.

Who is most vulnerable to tuberculosis?

Shete said immigrants to the U.S. are disproportionately affected by tuberculosis, though they're screened for latent infections before entering the country.

In 2020, more than 71% of all active tuberculosis cases in the U.S. were among people born outside the country, according to CDC data. More than half of new cases that year were among people born in Mexico, the Philippines, India, Vietnam or China.

"Unfortunately, screening and testing of the millions of at-risk individuals in immigrant communities estimated to be at risk for latent tuberculosis infection (LTBI) is lagging," Shete and several colleagues wrote in an editorial in the journal JAMA on Tuesday.

The editorial noted that around 80% of U.S. tuberculosis cases occur among racial or ethnic minority groups.

Tuberculosis is 70 times more prevalent among Asian people in the U.S. who weren’t born in the country than among U.S.-born white people, CDC data shows. Among U.S.-born Asian Americans, tuberculosis cases rose more than 62% from 2021 to 2022.

"These communities are intertwined," Shete said. "U.S.-born Asian communities are sometimes within the same household as non-U.S.-born Asian communities."

Homeless shelters or correctional facilities also bring a higher risk of infection, since residents live in close proximity. Tuberculosis was 11 times more common among people experiencing homelessness than among the general U.S. population as of 2016, according to an analysis published in 2021.

From 2021 to 2022, there was a nearly 61% increase in tuberculosis cases among correctional facility residents. Chaisson said that could be due to reduced testing earlier in the pandemic.

But the U.S. can reverse these trends, Davis said.

"It is realistic, actually, to eliminate TB in the United States in our lifetime," he said. "That’s really what we should be working for."