A Hidden World Underground
Every day, New York City’s subway shuttles millions of commuters through crowded tunnels. But in 2015, researchers at Weill Cornell Medicine discovered that these stations carried more than just passengers. Swabbing surfaces across all 466 open stations, they revealed a microbial ecosystem of 637 different organisms, many harmless, but some far from it.
Anthrax and Plague on the Rails
Among the rarest yet most alarming discoveries were traces of Bacillus anthracis, the bacterium that causes anthrax. Only two of 4,200 samples tested positive, and neither contained live bacteria. The study stressed that residents were not at risk, as anthrax cannot spread between people.
Even more surprising, DNA fragments of Yersinia pestis, the pathogen behind the bubonic plague, appeared in three samples. No live bacteria were detected, and the last plague cases linked to the U.S. had occurred in New Mexico, not New York.
Deadly Meningitis and Resistant Bacteria
Far more common was the presence of bacteria linked to meningitis, with Streptococcus suis appearing in 66 stations. Meningitis causes inflammation around the brain and spinal cord, leading to fever, headache, and neck stiffness.
Unlike anthrax or plague, it spreads through close contact, though not simply by sharing subway air. The researchers also found antibiotic-resistant bacteria in 220 stations, including strains capable of evading once-reliable treatments. These microbes underscored the ongoing challenge of drug resistance in modern medicine.
Food Poisoning in the System
Perhaps most relatable was the discovery of Bacillus cereus, a bacterium that causes food poisoning. It appeared in 215 stations, yet the subway itself posed no real risk. Infection occurs from contaminated food, not from touching poles or benches. Still, the finding reflected the presence of everyday microbes in public spaces, reminding riders of the unseen world around them.
What It Means for Commuters
The Weill Cornell study made clear that while the subway harbors DNA from dangerous pathogens, New Yorkers are not threatened by a daily ride underground. Most detected microbes were inactive fragments, part of the urban environment rather than sources of disease.
For scientists, the research provided a unique map of microbial life beneath the city, showing both its diversity and its resilience to urban conditions.
Beneath New York, a hidden city rides with you.
In 2015, scientists swabbed benches, poles, and seats across 466 stations and mapped 637 microbes.
Most were harmless.
A few names jolted nerves and turned a commute into a detective story…🧵👇 pic.twitter.com/nIJhD3PRhM
— Fascinating True Stories (@FascinatingTrue) October 2, 2025