Something unusual happened at Archbishop Riordan High School last fall.
In September, a student at 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.
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.
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. The vast majority of all new cases (about 87 percent) occur in just 30 low- and middle-income countries.
But the disease is also making a comeback in wealthy countries. After 30 years of being on the decline, tuberculosis rates are rising in the United States.
What is tuberculosis?
Tuberculosis is a curable — but stubborn — disease caused by mycobacterium tuberculosis, which primarily attacks the lungs. The bacteria can live in the human body for years without causing symptoms or becoming infectious, a condition known as "latent tuberculosis." When left untreated, about 5 to 15 percent of latent TB cases progress to active disease, often in babies, small children, the elderly, and people with compromised immune systems.
Even active cases can be difficult to diagnose, however. Some people become infectious without experiencing symptoms. And among people who do experience symptoms, the most common complaint is a chronic cough, sometimes accompanied by things like chest pain or night sweats.
"I think the danger of tuberculosis is that it can look and seem like a lot of other things that aren't so bad," said Priya Shete, an associate professor of medicine and tuberculosis researcher at University of California San Francisco.
How contagious is TB?
Tuberculosis spreads primarily through the air, and a cough isn't required to infect someone else — regular breathing can do the trick. Left untreated, someone with active tuberculosis can infect 15 people a year.
Globally, TB infects about 10 million people and kills 1.5 million every year. In the US, approximately 13 million people have latent tuberculosis.
And how deadly is "deadly," exactly?
Both active and latent TB can be cured with an antibiotic regimen. Unfortunately, many people — especially in developing countries — lack access to health care and medication. Without treatment, roughly half of people with active TB eventually die from the disease. Although it was briefly outpaced by Covid-19, tuberculosis regained its title as the world's leading cause of death by infectious disease in 2023.
Why is tuberculosis coming back now?
Tuberculosis rates plummeted in the US and other wealthy countries in the mid-1900s, when improvements in nutrition, living conditions, sanitation, and, especially, the advent of antibiotics dramatically changed public health. But we live in a globalized society, and tuberculosis still exists around the world. That means it can pop up here, as well.
The Covid-19 pandemic also delayed diagnosis and treatment of TB, and that impact still has not been reversed. Today, new tuberculosis patients are often sicker by the time they're diagnosed than they were in pre-pandemic caseloads. Delays in diagnosis and treatment mean more time for the disease to spread.
In February alone, confirmed cases popped up 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, 91 latent infections, and two deaths.
How can people protect themselves?
Despite these recent outbreaks, you don't personally need to panic about TB if you live in the US. We don't currently see much community transmission here. Instead, the disease typically spreads in places that lack sufficient health care services or are overcrowded, like prisons and homeless shelters.
That said, the further gutting of US public health infrastructure and research funding jeopardizes our ability to keep the incidence of this disease so low. And funding cuts to programs like USAID could lead to millions more tuberculosis deaths in the next five years, as well as a marked increase in drug-resistant cases.
"The global is local and the local is global," Shete said. "So if we're not able to address the global burden of tuberculosis, we'll continue to see it everywhere."
Read Shayna's full story here.
