Kimberly K. Repp of Oregon Health and Sciences University and William E. Keene of the Oregon Public Health Division in Portland investigated the norovirus outbreak in a group of 17 Oregon girls, ages 13-14 and their four adult chaperone's attending a soccer tournament in Washington state.
All had traveled in private automobiles, shared hotel rooms and eaten at local restaurants.
The investigators said one of the girls was presumably infected prior to the trip and seven others were infected while on the trip.
Before her overt symptoms began the infected girl left her room and moved in with a chaperone, and she subsequently began vomiting and having diarrhea in the chaperone's bathroom.
After her symptoms began, there was no direct contact between the original patient and her teammates.
The outbreak affecting the rest of the team began several days later after they were exposed by handling a bag of snacks that had been stored in the chaperone's bathroom, the investigators said.
"Virus aerosolized within the bathroom likely settled onto the grocery bag and its contents," the investigators said in a statement. "Matching viruses were found on the reusable shopping bag two weeks later."
Food should never be stored in the bathroom and areas where aerosol exposures might have occurred should be thoroughly disinfected, Repp advised.
The findings were reported in The Journal of Infectious Diseases.