BAYONNE, New Jersey - It has not been the best season for cruise ships. By the time the Explorer of the Seas docked at Bayonne, New Jersey, late last month, more than 600 passengers and crew members were sick to their stomachs; the Caribbean Princess arrived in Houston the same day after an outbreak sickened at least 192 people onboard.
Over the past five years, an average of about 14 cruise ships a year have had outbreaks of diarrhoeal illness, and the culprit is almost always norovirus, as it was on these two ships.
So if you go on a cruise, are you putting yourself at risk for this illness? Well, not exactly, but the answer is complicated.
It spreads through contaminated food or water or by contact with contaminated surfaces. In addition to loose stools and vomiting, it can cause weakness, muscle aches, headache and fever. There is no treatment and most people recover in a few days.
The best way to avoid it is prevention, and the best prevention is hand washing. The Centers for Disease Control and Prevention recommends that cruise ship passengers wash before eating or any other action that involves bringing hands near the mouth. And it recommends washing your hands after using the toilet, changing a baby's diaper and coming into contact with communal features such as railings.
Though cruise outbreaks make news, Mr Jan Vinje, head of the National Calicivirus Laboratory at the Centers for Disease Control and Prevention, said that widespread illness occurs on only about 1 in 200 voyages.
The cause is not necessarily cruise line maintenance.
"The food served on ships is usually of excellent quality, and food preparers are well trained," Mr Vinje said. And when illness appears, he added, crews clean quickly and effectively.
The problem, he said, is passengers.
"If grandma is sick when she gets on, she's going on the cruise anyway," he said. "And that's how the virus gets onboard. Then it lands on handrails and doorknobs, and the transmission continues."
Dr Philip Carling, a clinical professor of medicine at Boston University, said that regardless of the origin, once onboard, the illness spreads widely. He said the reason is failure to clean restrooms properly.
"Of course, they've been doing a good job with food," he said. "And if a person vomits, they soak everything in bleach. But they're not doing any routine examination of cleaning processes."
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