Bubonic Plague in the Subway System? Don’t Worry About It

No human being has caught it in New York City for at least a century, but still, there it was, researchers said, in places touched by hundreds, maybe thousands, of people every day.

After swabbing more than 400 subway stations for all kinds of microorganisms, researchers at Weill Cornell Medical College reported this week that they had found evidence at points across the city of bubonic plague, the Black Death that ravaged 14th-century Europe.

This was hardly surprising. Everyone who rides the subway knows it is teeming with rats, which in the right environment can be infested with fleas that carry plague. Medieval quantities of rats.

It also is scary. Could a subway turnstile be all that is standing between New Yorkers and a nearly forgotten disease?

“The strain of plague from the Middle Ages was a particularly bad strain,” he said.

“New York City today,” he also noted, “by comparison, even though some people might complain, it’s a far cleaner environment than the Middle Ages.”

What’s next for Dr. Mason and his pathogen-mapping team? First they will see if they can link the suspected plague DNA to the rats, he said. Then they will try to refine their DNA matching to look for two other notorious urban pests, cockroaches and bedbugs.

A version of this article appears in print on February 7, 2015, on page A15 of the New York edition with the headline: Bubonic Plague in the Subway System? Don’t Worry About It. Order Reprints| Today’s Paper|Subscribe

The New York Times