Public health researchers identified food stored inside a reusable grocery bag or the bag itself as the source of a 2010 norovirus outbreak that sickened seven children and adults from Oregon who attended a soccer tournament in neighboring Washington state.

The grocery bag contained cookies, potato chips and fresh grapes, and was kept in the bathroom of a hotel room where one of the girls who got sick stayed with an adult chaperone.  The person who put the bag in the bathroom was not aware that someone in the room was ill.

People who either touched the bag or consumed the food inside it became ill, according to the case study.

"This is the first published report of norovirus infection without person-to-person transfer," said Kimberly Repp, a case study co-author and now an epidemiologist with Oregon's Washington County Health & Human Services.  "Two groups of people were infected by transportation of an inanimate object."

While the sick child, who was suffering from vomiting and diarrhea, said she did not touch the bag or its contents, she did use the bathroom - with the bag sitting there - throughout the night.

The next day, the bag ended up in another hotel room and the contents were handled and eaten by other members of the group.  After that, the others eventually became ill.

Norovirus can be transmitted by tiny particles of vomit and feces floating in the air, so the virus can easily contaminate surfaces and objects.

"When people are sick in a bathroom, we all need to think beyond cleaning the toilet," Repp said.  "We need to clean all the surfaces where the virus may have landed and everything else in the bathroom."

One person who fell ill sought medical attention, but no one was hospitalized.  Five other people in team members' homes contracted the virus after the girls got home and got sick.  The virus can be shed in stool for up to two weeks after a person becomes ill.

If anyone gets the virus, containing it as much as possible is essential to preventing its spread.

"When possible, quarantine or isolate sick people to a single bathroom," Repp said.