There have been about 14 cruises a year in the past five years which have had outbreaks of vomiting and diarrheal illnesses almost always tied to the norovirus, even with multiple cruise inspections a year, the New York Times reported.
Most recently, the Royal Caribbean ship Explorer of the Seas returned from a trip earlier than expected with more than 600 sick passengers and crew members, according to the Times. The Caribbean Princess arrived in Houston the same day after an outbreak sickened at least 192 people onboard.
The Centers for Disease Control and Prevention reported about 20 million Americans are infected with the Norovirus yearly because the virus thrives in closed quarters like dormitories, summer camp cabins and cruise ships, according to the Times.
Jan Vinjé is the head of the National Calicivirus Laboratory at the Centers for Disease Control and Prevention and said even though the cruise ship outbreaks have made headlines, the illness only occurs in about 1 in 200 cruises, the Times reported.
"The food served on ships is usually of excellent quality, and food preparers are well trained," Dr. Vinjé said, referring to maintenance and cleanliness procedures as cause for the spreading of the illness, according to the Times.
"If Grandma is sick when she gets on, she's going on the cruise anyway," Dr. Vinjé said, the Times reported. "And that's how the virus gets onboard. Then it lands on handrails and doorknobs, and the transmission continues."
Norovirus spreads through contaminated food or water or by contact with contaminated surfaces, and once infected, the person can do nothing but wait it out for a few days, according to the Times.
The agency recommends that cruise ship passengers wash before eating or any other action that involves bringing hands near the mouth as the best way to preventing the illness from spreading, the Times reported. Proper cleaning of a baby's diaper change center and communal features like railings are essential, according to the agency.
A clinical professor of medicine at Boston University Dr. Philip C. Carling said the failure to clean restrooms properly is the main reason why the illness spreads so rapidly, the Times reported.
In a study published in Clinical Infectious Diseases in 2009, he marked toilet seats, flush handles and other objects in restrooms on cruise ships with an easily removed substance, visible only under ultraviolet light. Then examiners returned the next day to see if the substance had been wiped away, according to the Times.
Only 37 percent of the 8,344 objects marked were cleaned daily. On three ships that had baby-changing tables, none were cleaned at all during the three-year study period, the Times reported.
"Of course they've been doing a good job with food," Dr. Carling said, according to the Times."And if a person vomits, they soak everything in bleach. But they're not doing any routine examination of cleaning processes."
The C.D.C. does inspect ships but not every changing table or bathroom even, according to Bernadette Burden, an agency spokeswoman, the Times reported.
"We inspect some bathrooms, and we don't inspect for norovirus," Burden said.
