Norovirus Cleaning Begins at Dulles Hotel

The Hilton Washington Dulles Airport hotel closed yesterday for the weekend so crews could scrub and sanitize every surface after about 120 employees and guests were sickened by the highly contagious norovirus, which officials say is particularly severe this year.

As the last guests filtered out early in the afternoon, workers from a professional cleaning company prepared to scrub every nightstand and counter twice with a chlorine bleach solution. The crew will also clean carpets and drapes and mist each room with a disinfectant.

"It's a floor-by-floor, room-by-room, surface-by-surface process," said Jim Cree, the hotel's director of sales and marketing, who was washing his hands more than hourly yesterday to avoid the bug. "This will be the most sanitized building in the country."

This season is shaping up to be a particularly severe one for the illness sometimes known as "winter vomiting disease," said an expert at the federal Centers for Disease Control and Prevention, which helps track some of the 23 million cases of norovirus infection that occur each year.

First identified in 1972 but only routinely tested for in the past decade, norovirus is perfectly suited for causing dramatic outbreaks in crowded settings, including cruise ships, hospitals, nursing homes and hotels.

Even a very small amount of the virus can cause infection. It survives prolonged periods on such surfaces as counters and door handles, and it can become airborne under some circumstances. Some common disinfectants -- such as alcohol-based waterless hand scrubs -- won't kill it.

The chief mystery about the microbe, to both scientists and the public, is whether norovirus infections are becoming more common or just better publicized.

"That is the key question, and I don't think we really have an answer to it," said Robert L. Atmar, a norovirus researcher at Baylor College of Medicine in Houston.

"We certainly have better tools to diagnose the infection now, and they are being applied more frequently. That said, it seems that in the last year, there has been an increase in the number of norovirus outbreaks that have been reported," he said.

Marc-Alain Widdowson, a medical epidemiologist at CDC, said that "this winter season seems to be worse than previous winter seasons. The last time we had things this bad was 2002-03."

The severity of outbreaks may vary year to year, as is the case with influenza, even if the long-term incidence is not rising, he said.

Current estimates are that at least half of the more than 75 million annual cases of food-borne illness in the United States are caused by norovirus. About 20 percent of people who go to a doctor because of acute diarrhea are infected with it. The virus is believed to cause 10 times as many cases of diarrhea-and-vomiting illness as the next-most commonly implicated microbe.