Health officials are raising the alarm over a large and ongoing tuberculosis (TB) outbreak in Kansas.
According to data from the Kansas Department of Health and Environment (KDHE), the cases have all occurred in Wyandotte County and Johnson County, both part of the greater Kansas City metro area. So far, 67 "active" TB infections and 79 "latent," or "inactive" infections have been linked to the outbreak.
In latent TB, the immune system suppresses the bacteria — called Mycobacterium tuberculosis — behind the infection. Although they're inside the body, the bacteria don't cause any symptoms and can't spread to additional people. While many people with latent TB never develop active TB, about 5% to 10% do. This is more likely to happen to people with malnourishment, a history of smoking or tobacco use, or who have weakened immune systems, due to diabetes, immune-suppressing drugs or infections like HIV/AIDS.
"This outbreak is still ongoing, which means that there could be more cases," Jill Bronaugh, the KDHE communications director, told Live Science by email. The earliest cases linked to the ongoing outbreak took place in January 2024. Two deaths in 2024 were connected to the outbreak.
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With 67 active cases reported between January 2024 and the present, Bronaugh added that the outbreak is "largest outbreak in the U.S. at this time over the span of one year since the CDC began reporting TB cases in the 1950's."
That national recordkeeping started after the first effective treatments for TB were developed in the 1940s and 1950s, when improvements in housing and nutrition had already been helping drive down cases nationwide.
"According to CDC, a TB outbreak is generally defined as a situation where there are more TB cases than expected within a geographic area or population during a particular time period, AND [there is] evidence of recent transmission of M. tuberculosis among those cases," Bronaugh clarified. "Recent" transmission is often defined as happening within the past two years, she added.
The annual rate of active TB cases and TB-related deaths currently remains low in the U.S., especially compared to countries where the disease is widespread. However, cases have been on the rise in recent years. In 2023, the Centers for Disease Control and Prevention (CDC) recorded over 9,600 active TB cases nationwide, or about 2.9 per 100,000 people. That's about 15% more than reported in 2022, and the most reported since 2013.
Notably, in 2021, Kansas experienced an outbreak of multidrug-resistant TB that affected just over a dozen people. These infections are trickier to treat because the bacteria show resistance to common first-line antibiotics used to cure TB. Live Science asked KDHE if any of the cases in the current outbreak are drug-resistant but did not receive a response by the time of publication.
The health department is currently working with infected patients to identify close contacts who may have been exposed. Anyone who tests positive will be further examined to see if they have active or latent TB, since that dictates which treatment they receive. Although there is a vaccine for TB, it is generally not used in the U.S. because the risk of infection is so low, according to the CDC.
Treatments for TB typically involve taking multiple antibiotics for months at a time. Local health departments will provide these treatments to the patients in Kansas, and they will be free for those who are underinsured or uninsured, KGHE said.
TB-causing bacteria spread through the air, and are released when a person with active TB in their lungs speaks, sings or coughs. Once in the body, the bacteria can also spread beyond the lungs to other organs, such as the kidneys, spinal cord or brain. The symptoms a person experiences depend on which body parts are infected, but active TB in the lungs causes cough (including coughing up blood), chest pain, weakness, weight loss and fever, for example.
"TB is spread person-to-person only through prolonged contact with someone who has active TB," Bronaugh emphasized.
As of Jan. 28, KDHE is managing 384 individuals linked to the outbreak who are in various stages of testing, diagnostics and treatment. Its case counts are being updated weekly.
"While there is a very low risk of infection to the general public in these communities, KDHE is working to ensure that patients are receiving appropriate treatment, which will limit the ability to spread this disease and prevent additional cases from occurring," Bronaugh told Live Science.
"KDHE and public health professionals from the CDC are working together to mitigate the risk of TB in the community and ensure the safety of all individuals," she said.
Editor's note: Live Science originally published this article on Jan. 28, 2025, after receiving initial comments from KGHE. The department then sent out new information on Jan. 29, and the article was updated the same day.
