Scientists Say Reusable Grocery Bags Help Spread Norovirus

Posted on May 10, 2012

Norovirus CDC


Scientists in Oregon have linked transmission of the norovirus to reusable grocery bags. The norovirus is a nasty virus that can cause simultaneous vomiting and diarrhea. It is known for ripping through cruise ships and nursing homes, but it also spreads among the general population causing vomiting outbreaks. A 2010 study found that 97% of people do not ever wash their reusable bags. This makes them vessels for bacteria and viruses, like the dreaded norovirus. Half of the bags tested in the study contained bacteria found in fecal matter. People hauling around these dirty bags are basically carrying the norovirus and other bugs with them to and from the grocery store and spreading it everywhere they go.

Oregon investigators recently mapped the trail of an outbreak of norovirus among participants in a girls' soccer tournament to a reusable open top grocery bag stored in a hotel bathroom. Their findings illustrate the role that inanimate objects can play in spreading norovirus infection. The study appears here in the Journal of Infectious Diseases.

In the study, Kimberly K. Repp, PhD, MPH, of Oregon Health and Sciences University, and William E. Keene, PhD, MPH, of the Oregon Public Health Division in Portland, investigated an outbreak in a group of 17 Oregon girls, 13-14 years old, and their four adult chaperones attending a soccer tournament in Washington state. All had traveled in private automobiles, shared hotel rooms, and eaten at local restaurants. Eight cases were identified, including the index patient who was presumably infected prior to the trip. There was no direct contact between the original patient and her teammates after her symptoms began; before her overt symptoms began she left her room and moved in with a chaperone. The girl subsequently began vomiting and having diarrhea in the chaperone's bathroom. The outbreak affecting the rest of the team began several days later. They were exposed by handling a bag of snacks that unfortunately had been stored in the hotel bathroom. Virus aerosolized within the bathroom likely settled onto the reusable grocery bag and its contents. Matching viruses were found on the reusable shopping bag two weeks later.

Noroviruses are highly contagious, even in low concentration, and the viruses spread efficiently from feces and vomit by direct and indirect contact. Aron J. Hall, DVM, MSPH, of the Centers for Disease Control and Prevention, says noroviruses "are perhaps the perfect human pathogens," causing an estimated 21 million cases of acute gastroenteritis annually in the U.S. alone.

The authors of the study also say, "While we certainly recommend not storing food in bathrooms, it is more important to emphasize that areas where aerosol exposures may have occurred should be thoroughly disinfected; this includes not only exposed surfaces, but also objects in the environment."

In this case one of the objects exposed was a reusable grocery bag. The researchers say in their report, "Illness was associated with touching a reusable grocery bag or consuming its packaged food contents."

The 97% of people that never clean their dirty reusable grocery bags are certainly not thoroughly disinfecting their bags. The CDC says one of the ways the norovirus can be transmitted is by "touching surfaces or objects contaminated with norovirus then putting your fingers in your mouth." The norovirus can stay in your stool for 2 weeks or more even after you feel better.

Photo: CDC/ Charles D. Humphrey, PhD