TUESDAY, Jan. 7, 2003 (HealthDayNews) -- Major outbreaks of Norwalk-like virus that have infected 700 people in Boston provide the latest evidence that the nasty stomach bug that sickened so many cruise ship passengers is hardly limited to the high seas.
In fact, experts say, the gastrointestinal illness is much more prevalent on land.
The 17 Boston outbreaks struck nursing homes, rehabilitation centers, homeless shelters and hospitals during the past six weeks. Local health authorities call the outbreaks the worst in almost two decades since the viruses were identified. Symptoms include diarrhea, vomiting, stomach pain and headaches for up to two days.
Experts say the outbreaks reflect an upsurge in the number of cases of Norwalk-like viruses, which are named after an outbreak in Norwalk, Ohio, in 1968.
Federal health officials blame the same viruses, the leading cause of gastrointestinal illness, for nine outbreaks aboard cruise ships within the past six months.
The cruise ship stomach bugs gave new meaning to "seasick," creating memories vacationers would just as soon forget, and drew international headlines that suddenly made Norwalk-like viruses a familiar term.
But the cruise ship viruses represent but a tiny fraction of at least 23 million Norwalk-like illnesses in the United States each year, federal health officials say. They add that the number could be much greater because many cases likely go unreported.
"There's little doubt that what's going on in cruise ships is a reflection of what's happening on land," says Dr. Marc-Alain Widdowson, a Norwalk virus specialist at the U.S. Centers for Disease Control and Prevention. "There's no reason to think there's any greater risk on a cruise ship than any other place with people in close proximity."
Outbreaks at sea and on land show just how quickly and easily the viruses spread, especially when lots of people are packed into confined areas.
Norwalk-like viruses most often spread through tiny amounts of fecal matter when people don't wash their hands after using the bathroom, Widdowson says. Extremely contagious, the viruses can be transmitted through a handshake or other physical contact, on surfaces or through contaminated food or water. Even breathing tiny particles from vomit can spread the viruses through the air, he says.
Recovery normally comes by the third day without treatment, and hospitalization is rare. But those with heart disease, diabetes or other conditions that make loss of fluids particularly risky should seek medical care, health experts say.
Simple steps like regular, thorough handwashing and avoiding physical contact with infected people could go a long way toward preventing the spread of the viruses, experts say.
Dr. Anita Barry, director of communicable disease control at the Boston Public Health Commission, says her city's outbreaks "certainly demonstrate that it's not hard to spread these types of viruses and also demonstrate there's a lot of room for improvement in hygiene."
She and other public health officials hope that message takes hold at a time when widespread anecdotal evidence suggests significant increases in the number of outbreaks.
In Minnesota, for instance, health officials reported an "unprecedented" 25 separate Norwalk-like outbreaks, sickening as many as 1,000 people in November and December, at sites including restaurants, schools, hospitals and nursing homes. And in Canada, officials in Edmonton and central Alberta report the worst outbreaks in 20 years, afflicting more than 1,000 people.
Health experts also urge cruise ship passengers to wash hands regularly and avoid contact with infected people. And the CDC's Widdowson says disinfectants like bleach and chlorine gas are effective at destroying Norwalk-like viruses aboard ships.
But, he says, cleaning efforts are complicated because the viruses are tough to detect on surfaces.
Just how tough became evident after Disney Cruise Line thoroughly scrubbed down its 2,600-passenger Magic cruise ship, only to have stomach illnesses recur on the next cruise aboard the same ship.
Still, there's no epidemic at sea, and the odds of picking up a bug are slim, considering that 7 million people were estimated to have boarded cruise ships in North American last year, industry officials say.
Mark Jaronski, a Disney Cruise Line spokesman, says the company worked closely with the CDC and heeded advice to develop more-thorough sanitization.
Jaronski says the coverage of shipboard illnesses has had no effect on bookings. "It got to somewhat hysterical levels, but I think if you put it in perspective, many of the obvious questions are answered pretty easily," he says. "People are experiencing these symptoms across the country and globe. There's nothing unique to the ships."
The CDC attributes more of the recent gastrointestinal illness on ships to Norwalk-like viruses than to any other cause. Of 21 outbreaks in the past six months -- defined as gastrointestinal illness among at least 3 percent of the people on a ship -- nine resulted from Norwalk-like viruses. Bacteria caused three other outbreaks, and the cause of nine others remains unknown, the CDC says.
What To Do
For more on Norwalk-like viruses, visit the Virginia Department of Health. For more on cruise ship sanitation, see this
CDC site.
