Viruses Spread Through Public Places Scarily Fast

You are a walking vector of disease—not just you, but all of us. Especially the children. In fact, it takes just  hours for the microbes living on your body to cover your home. But how long does it take for an invading, diarrhea-causing human norovirus to spread across your house, office building, hotel, or hospital? Not long at all, it turns out, thanks to you and your grubby, disgusting hands.

Chuck Gerba, a professor of Microbiology at the University of Arizona, just presented a  study at the Interscience Conference on Antimicrobial Agents and Chemotherapy where he found that the norovirus basically screams across surfaces.

It takes just hours from the time a virus is introduced on a tabletop or doorknob for it to appear all over the building's fomites, or surfaces capable of sustaining microbial life, as well as everyone's hands.

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

In order to clock the viral spread, Gerba and his team went to buildings introducing an infection of bacteriophage MS-2.

"It doesn't infect people, and it has the same size, shape, and resistance to disinfectants as the norovirus," he said.

When I asked how he could be sure all the found phages were from the study, he told me that bacteriophage MS-2 "doesn't occur naturally in the background. We first checked all the offices and hotels to make sure there was none of this virus there."

There wasn't, and then there was, and the gap between the two was pretty slight. And lest you think, "I don't have norovirus and I don't live in a hotel, hospital or office building," Gerba is here to disabuse you of that thinking. Not only does his test also apply to flus and colds, it applies to your home.

"We've done these studies in the house too, and you'd be surprised what happens when you put a virus on an adult hand," he said. "It's basically on all the other people's hands and the surfaces they touch within a few hours."

And if you have kids it's even faster. "Usually a house has one to three colds a year, but it depends on how many kids you have—the more kids you have, the more colds you have," Gerba said. "I guess that's another preventative measure: Don't have children."

Despite that warning, procreation remains a popular activity, so it's nice to know that Gerba and his team also found that norovirus is far from being an unstoppable scourge.

"What we found was that if we provided these households with hand sanitizers or disinfecting wipes, we could reduce the amount of virus they're exposed to by 99 percent," Gerba said. "Because colds and flus go around all the time, it's probably a good idea to use them at least once a day. We found once to three times a day using a hand sanitizer is all you needed. If no other time of the year, then at least during cold and flu season."

So there you go. As summer wraps up, viruses are going to be whipping around your home shortly, so either get rid of your kids, or pick up some Purell. Probably just pick up the Purell.