Many members of the group arrived complaining of gastrointestinal symptoms, which were later determined to have been caused by norovirus.
The virus, which is transmitted via the fecal-oral route spread to others in the park, eventually sickening more than 100 employees and 50 visitors in mid to late June. At least 50 illnesses were also reported among employees at neighboring Grand Teton National Park.
As of Tuesday, however, no new norovirus cases had been reported in the area in over a week, a Yellowstone spokesperson told Food Safety News.
She did not know where the tour group that introduced the virus had begun its trip.
The National Park Service said it has taken extra measures to prevent the spread of infection, including increased cleaning and disinfection of all public areas such as stores, gift shops, restaurants, and lodging facilities. Employees who were potentially infected were isolated until they have been symptom-free for at least 72 hours.
While the outbreak appears to be “tapering off,” she said, it’s still important to take precautions to prevent the spread of norovirus, the most common cause of gastrointestinal illness in the U.S., when visiting the park.
“Wash your hands. That’s the biggest thing,” she advised. “People tend to forget to wash their hands with soap and water before they eat, especially on vacation. They’re touring and then walk into the restaurant and don’t think of going to the restroom first to wash their hands.
“People tend to rely on hand sanitizer, but it just isn’t as effective against norovirus as plain old soap and water.”
A woman who visited the park this week said there are still signs in park restrooms informing park visitors of the outbreak and advising them to practice good hand hygiene to avoid the spread of illness.
A representative from the Wyoming Department of Health told Food Safety News that the Department’s epidemiologists are monitoring the outbreak in case it spreads beyond the parks into neighboring counties.© Food Safety News