Tracking Germs on Public Transit Could Help Predict Epidemics

The dirty reality: researchers who swabbed subway cars and ticket machines in Boston found surprisingly low numbers of harmful microbes. They intend to use this data as a baseline to help anticipate future epidemics and other public health crises. The team published their findings in the journal mSystems.

For the study, the scientists headed into stations along the subway system’s Red, Green, and Orange lines on three separate weekdays in May and October in 2013. They swabbed the touchscreens and sides of ticket machines, as well as the seats, seat backs, poles, and wall grips inside train cars, carefully recording the precise location of the swabbing site. Back in the lab, the researchers picked through the swabs’ microbial communities, creating a DNA profile for each site.

They found that the public transit environment was positively teeming with bacteria and other microorganisms. Poles and hand grips were liberally smeared with Propionibacterium, Corynebacterium, Staphylococcus, and Streptococcus—species all commonly found on human skin and in our mouths. Seats hosted Corynebacterium and the vaginal bacteria Gardnerella. (It's important to note that Gardnerella can easily be transmitted through clothing.) And plant bacteria were found all over outdoor touchscreens. There were no major differences between train stations or lines.

So yes, germs were everywhere, but the presence of germs isn’t necessarily a bad thing, according to Curtis Huttenhower, a computational biologist and senior author on the study.

“We were surprised to find that the microbes that we collected on surfaces that people touch—and sometimes sneeze on—had low numbers of worrisome pathogens or antibiotic resistance genes,” Huttenhower said in a press statement. “These environments have drastically lower virulence profiles, in fact, than are observed in a typical human gut.”

Now, just because the subway wasn’t disease-ridden doesn’t mean these findings are useless. Far from it, Huttenhower says. “Our findings establish a baseline against which deviations can be used as an early warning system to monitor public health.”

Know of something you think we should cover? Email us at tips@mentalfloss.com.