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The world’s deadliest infectious disease is on the rise in the US

We discovered its cause 144 years ago. It’s still a massive problem.

Something unusual happened at Archbishop Riordan High School last fall.

In September, a student in the Bay Area school went to see a health care provider for a cough that wouldn’t go away. But it wasn’t until two months later that the student got diagnosed: tuberculosis. The San Francisco Department of Public Health (SFDPH) launched an investigation, which revealed a surprisingly high rate of latent tuberculosis — meaning that people were infected by the Mycobacterium tuberculosis bacteria, but their infections had not yet progressed to active and contagious disease — at the school.

As of February 24, the most recent data available, four people in the school community had confirmed active tuberculosis, and an additional three active cases were suspected by the public health department.

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A private school in San Francisco isn’t exactly where you would expect a tuberculosis outbreak to occur. Tuberculosis is largely a disease of poverty and marginalization, and today the developing world bears the greatest burden. The vast majority of all new cases (about 87 percent) occur in just 30 low- and middle-income countries.

But it used to be far more prevalent globally. Rewind the clock: On March 24, 1882, a German physician named Robert Koch announced that he had identified the cause of the illness that killed one out of every seven people in the US and Europe. Now fast-forward: Today is World Tuberculosis Day, marking the 144th anniversary of Koch’s discovery. And the disease is making a comeback in wealthy countries.

Call it consumption, “the robber of youth,” the white plague — but we certainly can’t call it gone. And although it was briefly outpaced by Covid-19, in 2023 tuberculosis regained its title as the world’s leading cause of death by infectious disease. Every year, it infects about 10 million people and kills 1.5 million — despite being both preventable and curable. Counting both latent and active cases, a fourth of the entire human population may be infected with the bacteria worldwide.

“The global is local and the local is global, so if we’re not able to address the global burden of tuberculosis, we’ll continue to see it everywhere,” Priya Shete, an associate professor of medicine and tuberculosis researcher at University of California San Francisco, told me. “We’ll start to see tuberculosis arise in the least expected places.”

The United States has the infrastructure for tuberculosis testing and treatment, and it isn’t currently endemic here. Like much of the world, it used to be though — it may have killed as many as a quarter of all Americans during parts of the 18th and 19th centuries. But improvements in nutrition, living conditions, sanitation, and, especially, the advent of antibiotics in the mid-1900s changed things dramatically. Still, “not endemic” is a far cry from “eradicated.”

After 30 years of being on the decline, tuberculosis rates are rising in the US. In February alone, it popped up in American high schools beyond the Bay Area, with confirmed cases in Long Island, New York and Seattle. One of the largest American outbreaks since the Centers for Disease Control and Prevention started reporting tuberculosis data in the 1950s happened just two years ago in Kansas, leading to 68 active cases,........

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