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Germs Spread Unbelievably Fast in the Workplace

It can take as little as 2 hours for one stomach-flu sufferer to contaminate half of a single office.

Say some under-the-weather person at your workplace coughed into their palm and touched a doorknob. Beginning with that one contaminated object, how long would it take for the virus to run rampant through the building?

Would it be a day? Eight hours? Perhaps the best answer if you're a germophobe is "You really don't want to know," because scientists have tested this scenario and the speed can be frighteningly quick. From the instant those unsanitary fingers touch the knob, it could be just 2 to 4 hours before the contagion has spread to 40 to 60 percent of frequently handled surfaces, as well as your coworkers. Take a moment now to wash hands.

This distressing assessment comes from infectious-disease researchers attending this week's Interscience Conference on Antimicrobial Agents and Chemotherapy in Washington, D.C. (One of them's giving a live talk this morning if you want all the grody details.) For their study, they picked a real doozy of a bug to simulate—norovirus, aka the "super stomach flu" made so famous by cruise-ship journeys to hell. Norovirus, which is often spread by touching contaminated objects and then your mouth, is the most common source of acute gastroenteritis in America. Each year it causes as many as 71,000 hospitalizations, 800 deaths, and millions of grotesque trips to the bathroom.

Charles Gerba of the University of Arizona and colleagues didn't devise a norovirus outbreak, of course. They used a bacteriophage that has the same shape and endurance level against disinfectants. Here's Gerba describing how the researchers proceeded:

The phage was placed on 1 to 2 commonly touched surfaces (door knob or table top) at the beginning of the day in office buildings, conference room and a healthcare facility. After various periods of time (2 to 8 hours) they sampled 60 to 100 fomites, surfaces capable of carrying infectious organisms (light switches, bed rails, table tops, countertops, push buttons, coffee pots handles, sink tap handles, door knobs, phones and computer equipment), for the phages.

"Within 2 to 4 hours between 40 to 60% of the fomites sampled were contaminated with virus," says Gerba.

Thankfully for the nation's collective gut, the study did not end with a simple, You are doomed if somebody at work gets sick. The researchers did a followup experiment that managed to reduce the virus's spread by 80 to 99 percent. Their secret weapon? Making workers and janitorial staff use disinfectant wipes once a day. Says Gerba: "The results show that viral contamination of fomites in facilities occurs quickly, and that a simple intervention can greatly help to reduce exposure to viruses."

Top image: igor.stevanovic/

About the Author

  • John Metcalfe
    John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.