Five things to know about tuberculosis as it surfaces in Maine and North Carolina
One of the world’s most deadly infectious diseases, tuberculosis requires months of treatment
Tuberculosis, one of the world’s most deadly infectious diseases, has been reported in a handful of cases in Maine, North Carolina and California in recent weeks.
Less transmissible than other respiratory illnesses such as the flu and COVID-19, tuberculosis is curable with up to nine months of antibiotic treatment for active cases.
Northeastern University infectious disease and global health experts Brandon Dionne, Larry Han and Tamara Jimah explain what causes tuberculosis, how it spreads and why it requires months of medication to fully eradicate it.
What is tuberculosis?
Once believed to be an inherited disease, tuberculosis, also known as TB, is a bacterial disease caused by Mycobacterium tuberculosis.
“The name for tuberculosis actually comes from tubercles,” small lesions in the lungs caused by the disease, says Dionne, associate clinical professor in pharmacy and health systems science.
“It can start to destroy lung tissue,” he says. “When most people die of tuberculosis, it’s actually from tissue deterioration and respiratory failure.”
There are two types of tuberculosis, latent and active, with latent, non-transmissible cases being more prevalent, says Han, a biostatistician and Northeastern assistant professor of public health and health sciences.
“A person can live with latent TB for many years without knowing it until they get tested,” says Jimah, global health researcher and assistant professor of public health and health sciences.
Latent cases can turn active and contagious when a person’s immune system is weakened by events such as illness or immunosuppressive treatments, Dionne says, which is why people taking certain medications undergo TB testing.
Who is at risk?
Relatively rare in the U.S., tuberculosis is responsible for more than a million deaths annually in endemic countries, mainly in Asia and Africa, according to the World Health Organization.
“When we have a new diagnosis of TB, it’s usually from someone who immigrated to the U.S. from an endemic area,” says Dionne, who adds that U.S. residents can also pick it up in their travels.
How is it transmitted?
Tuberculosis is spread through respiratory droplets released through coughing or talking and is typically associated with tight living or traveling quarters, he says.
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People who live or used to live in large group settings such as homeless shelters, prisons and jails or who work in correctional systems, hospitals and nursing homes are at increased risk of contracting TB, according to the Centers for Disease Control and Prevention.
Those with weakened immune systems due to HIV, organ transplant, substance abuse and diabetes are also more susceptible.
“HIV weakens the immune system, which makes people more susceptible to contracting TB,” Jimah says. “On the other hand, TB also accelerates the progression of HIV. So this creates a sort of a cycle where each disease sort of worsens the other.”
Symptoms and diagnosis
When somebody tests positive for tuberculosis, a public health worker tracks their recent contacts, says Dionne, who is also a clinician at Brigham and Women’s Hospital in Boston.
“Ongoing transmission in the U.S. is very rare because of the public health tracing that we do to try to prevent new cases,” he says.
“For most people in the general population, there is probably low worry about tuberculosis unless they are experiencing symptoms of TB,” Han says.
Symptoms include swollen lymph nodes, shortness of breath, unexplained weight loss, night sweats and progressive but non-productive cough, Han and Dionne say.
Skin tests can detect exposure to TB, Dionne says, while blood and mucus tests and chest X-rays can determine if the infection is active.
Months of treatment
“With the right medicines, TB is totally treatable and curable,” Han says.
“But it’s a lengthy treatment that requires good adherence and often requires a combination of antibiotics,” he says.
“Most people get two months of four-drug therapy and then four months of (antibiotics) rifampin and isoniazid,” but treatment for more severe disease could last longer, up to nine months, Dionne says.
“When they’re in the hospital, we put them in negative pressure rooms so the bacteria can’t get out of the room,” he says. “Typically, they’re asked to mask and try to stay apart from other people, at least for the first couple of months they are on therapy.”
The Mycobacterium that causes tuberculosis is much slower growing than other bacteria, which makes it harder to eradicate since antibiotics work by interrupting the replication cycle, Dionne says.
Stopping medication too soon because of side effects or other issues can lead to lingering illness and antibiotic resistance, Han says, which is why some public health departments send observers into patients’ homes to ensure medication compliance.
Trends in case counts
While tuberculosis has been trending generally downward since 1993, when the U.S. had more than 25,000 cases, recent years have seen an upward blip.
Case counts surged 15.6% from 2022 to 2023, going from 8,332 to 9,633 cases.
A provisional report from the CDC released in March says cases continued to increase into 2024, climbing 8% to 10,347 cases in one year.
But despite cases popping up across the country this year, the preliminary figures for 2025 show another downward trend.
This year, there have been 5,310 cases of tuberculosis among U.S. residents, compared to 6,227 at the same time last year, the CDC said in a report for the week ending Aug. 16.
“The U.S. typically does not have that many cases,” Han says. “So even a single active case is cause for concern.”
