By Mike Stark of Montana Lee Newspapers
July 9, 2004

More than 130 visitors and workers became ill in Yellowstone National Park in late June during an outbreak of a highly infectious virus at Old Faithful and the Lake.

The cause of the illnesses appears to be a norovirus, a group of viruses that can cause stomach flu, also known as gastroenteritis. It’s the same bug that has sickened hundreds on cruise ships and caused earlier outbreaks at Yellowstone and Grand Canyon national parks.

The virus can cause vomiting, diarrhea, nausea and stomach cramping. Symptoms can come on quickly and usually last one to two days

“We’re very nervous systemwide about this virus. Not because it’s life-threatening or severe, but because it’s so prevalent,” said Charles Higgins, director of the National Park Service’s Office of Public Health.

Most of the afflicted people in Yellowstone started getting sick during the last week of June. Employees at a clinic in the park noticed the upswing in gastrointestinal problems and contacted authorities at Park Service headquarters.

Investigators said it appears the virus spread person-to-person and through contact with objects such as doorknobs.

“It doesn’t look like it got into the food service systems, which is really almost a miracle,” Higgins said. “That probably means (the concession company) did something well.”

The outbreak wasn’t surprising, especially at a place like Old Faithful where people often congregate in close proximity, Higgins said. It affected concession employees the most because they live in dormitories and share facilities, he said.

It’s still unclear where the virus came from and exactly how it spread, but Higgins said it doesn’t take much for the virus to rapidly spread.

“You might have a visitor who came in ill with the virus and threw up in their room. Then the housekeeper cleans it up, that person becomes ill and they go back to the dorm, throw up there, and then boom, 50 other people are ill,” Higgins said.

Park officials said 53 visitors got sick along with

71 concession employees and eight Park Service workers. Most people were sick for only a day or so and the outbreak tapered off sharply by the Fourth of July weekend.

Park officials, including a federal Public Health Service worker at Yellowstone full time, responded quickly to the outbreak and got cooperation from the Wyoming Department of Health and the concession company, said Cheryl Matthews, a Yellowstone spokeswoman.

Xanterra Parks and Resorts, the concessions company, took extra steps, including wiping down door handles and cleaning bathrooms more frequently, she said.

“They really stepped up,” Matthews said.

Norovirus makes an estimated 23 million people sick every year, according to the Centers for Disease Control and Prevention. The virus is most commonly spread through eating contaminated food, touching contaminated surfaces and having direct contact with people with symptoms.

The virus, formerly known as Norwalk virus, gained attention recently as the cause of hundreds of illnesses aboard cruise ships.

“It’s very infectious and tends to take advantage of people living close,” Higgins said.

In recent years, there have been outbreaks at Yellowstone’s Fishing Bridge and at Grand Canyon. Higgins said this year’s outbreak at Yellowstone is in the “mid-range in terms of size and length of time.”

Four investigators interviewed people who became sick, took samples and looked over medical records. The information will be sent to the Centers for Disease Control and Prevention for analysis.

Mike Stark writes for The Billings Gazette.