The Case of the Contaminated, Reusable Grocery Bag

by Mary Rothschild
Food Safety News
May 10, 2012
Original link: http://www.foodsafetynews.com/2012/05/the-case-of-the-contaminated-reusable-grocery-bag/

How Oregon epidemiologists solved a norovirus mystery

Oregon state senior epidemiologist William Keene is a fan of Berton Roueché, whose books, like Eleven Blue Men, revealed the whodunnit work of epidemiology.

Now Keene, of the Oregon Public Health Division, and fellow sleuth Kimberly Repp, of Oregon Health and Sciences University, have cracked a case and told a real-life detective tale worthy of Roueché.

Writing in The Journal of Infectious Diseases, available here online, Keene and Repp explain how in October, 2010, a group of Oregon soccer players, 13 and 14 years old, and some adult chaperones, came down with norovirus during a tournament in Washington state.

One of the girls apparently was infected prior to the trip, and began vomiting and suffering bouts of diarrhea late Saturday in the chaperone's hotel bathroom. The girl, who had no contact with her teammates after she became ill, was driven home in the morning.

But a reusable grocery bag filled with snacks -- packaged cookies, chips and grapes -- had been in the bathroom. The rest of the group ate that food during a Sunday lunch, and other members of the team were ill by Tuesday after they had returned to Oregon.

In investigating the outbreak, Keene and Repp found no connections to any other norovirus illnesses at the team's hotel, the tournament, or the restaurants where they had eaten. It wasn't until they learned about the bag in the bathroom that a "coherent story" emerged, Keene and Repp wrote.

Two weeks later, matching viruses were found on the sides of the bag.

Although the first sick girl said she did not touch the grocery bag, Keene and Repp theorize that the viruses had aerosolized in the bathroom and settled on the sack and the food items inside.

"What this report does is it helps raise awareness of the complex and indirect way that norovirus can spread," said Aron Hall, DVM, MSPH, with the Division of Viral Diseases at the Centers for Disease Control and Prevention, in an accompanying editorial. And in what could be a blurb for a Roueché-style book, Hall adds that the study authors provide "a fascinating example of how a unique exposure and transmission scenario can result in a norovirus outbreak."

The investigation shows how this tenacious virus "finds a way to move from host to host, even when those hosts have no direct contact with one another," Hall added.

Keene and Repp observe that "incidentally, this also illustrates one of the less obvious hazards of reusable grocery bags."

While they recommend not storing food in bathrooms, the study authors say "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" that could become
contaminated and spread infection.

In addition to thorough hand-washing, disinfecting affected areas with bleach- based solutions and dedicating bathrooms for use only by those who are sick are some practices that could limited outbreaks caused by such indirect contact, they suggest.

Noroviruses -- "perhaps the perfect human pathogens,"  according to Hall -- are the leading cause of gastroenteritis in the U.S. They are responsible for more than 21 illnesses, 70,000 hospitalizations and 800 deaths annually in this country alone. People can get norovirus illness throughout the year, but cases generally peak between December and February.