Study suggests ways to avoid stomach bugs on cruises

A few steps can help prevent the spread of stomach bugs on a cruise ship, according to a study published online today by the journal Clinical Infectious Diseases. Don't board if you're already sick. Seek help if you get ill

Researchers from the Centers for Disease Control and Prevention surveyed 1,533 patients who had been on a passenger ship stricken in January 2009 with an outbreak of norovirus, a highly contagious gastrointestinal bug that causes nausea, vomiting, diarrhea,and stomach cramps, and spreads rapidly in cramped, close quarters. 

A staggering 15 percent met the case definition for acute gastroenteritis, the illness caused by norovirus. But only 60 percent of those who became ill sought medical care on the ship, which might have helped ship staff contain the disease. Infected passengers were particularly likely to have had an ill cabin mate and to have either slept or dined on the ship's fifth deck, where an ill passenger had vomited in public during boarding. 

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A new studyis available online in the Oxford journal "Clinical Infectious Diseases" detailing the findings of an investigation into an outbreak of norovirus on a cruise ship in 2009. Norovirus is the most common type of food-poisoning in the United States. Usual symptoms of norovirus infection include nausea, vomiting, diarrhea, and abdominal pain. Headache and low-grade fever may also accompany this illness. The illness develops 24 to 48 hours after contaminated food or water is ingested and lasts for 24 to 60 hours.

According to the abstract, the study was based on a questionnaire placed in passenger cabins after the outbreak of illness. The questionnaire sought information on whether and when people sought medical care, personal hygiene, and potential norovirus exposures.

83% of the roughly 1,500 passengers returned the questionnaires. Of those who did, 15% were persons who met the case definition of an outbreak member. A full 40% of the ill persons did not report to the ship infirmary.

Two factors that appeared to increase the likelihood of illness were having an ill cabin mate, or residing or dining on a deck where a vomiting incident had occurred during boarding. Darrhea and vomiting were the two most common symptoms. Several ill persons did submit positive stool cultures.

Study Author Mary Wikswo, MPH, of CDC, was quoted in a report on Medical News Today:

"Cruise line personnel should discourage ill passengers from boarding their ships. Once on board, passengers and crew who become ill should report to the ship's medical center as soon as possible. These quick actions are crucial in preventing the introduction and spread of norovirus on cruise ships and allow ship personnel to take immediate steps to prevent the spread of illness."

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