Is It Norovirus Season at Sea?

January 8, 2010
Ah, the "joys" of winter: cold, flu and ... Norovirus? Not so fast.

The number of outbreaks of gastrointestinal illness onboard cruise ships doesn't necessarily spike during the winter, according to Captain Jaret Ames, the program director for the Centers for Disease Control and Prevention's Vessel Sanitation Program, which oversees health and sanitation aboard ships that visit U.S. ports. In fact, because Noro outbreaks can occur anytime, when a spike occurs will vary from year to year.

So, why is the gruesome illness often associated with winter -- and even referred to as the "winter vomiting bug" in the U.K.? Well, that's because even if there are not more cases than usual, you can almost rest assured that there will consistently be some cases in the winter. A likely cause is people spending more times indoors (to escape the cold, no doubt), which facilitates the spread of germs.

We got to thinking about wintertime bouts of Noro after receiving an e-mail from Editor in Chief Carolyn Spencer Brown, who's currently onboard Royal Caribbean's Oasis of the Seas, and spotted a passenger getting, ahem, sick on the sun deck.

Royal Caribbean spokeswoman Cynthia Martinez has confirmed that a small number of passengers and crew have reported gastrointestinal illness: 43 of 5,830 guests (less than one percent) and five out of 2,241 workers (less than one percent) on the sailing, which departed January 2 from Fort Lauderdale for a weeklong Western Caribbean cruise.

However, though it's certainly not "minor" to those who are feeling ill, it is a minor outbreak in the grand scheme of things. To put the numbers in perspective, cruise lines are required to report cases to the CDC when the total number of persons ill exceeds two percent -- not the case here (which means the CDC is not even investigating the ship for a Noro outbreak at this time). And we don't generally cover outbreaks until the total number of ill passengers exceeds 10 percent, because Norovirus is so prevalent; it's the second most common ailment next to the common cold.

Still, Royal Caribbean has responded with "an abundance of caution," according to Martinez; crewmembers are conducting enhanced cleaning to help prevent the spread of the illness, which Spencer Brown has seen in action: "There are a number of crewmembers wearing masks, everywhere from cabin corridors to elevator lobbies. A message on the fancy, new in-cabin televisions is also advising guests to wash their hands."

The only ship of interest for the CDC is Holland America Line's Noordam, which a CDC spokesperson says has exceeded the two percent mark with just over 40 passengers sick; a Holland America spokesman was unable to provide more details by press time. Three North America-based ships reported numbers above two percent in December, and Fred. Olsen had a series of outbreaks in the U.K. Otherwise, it's been a pretty quiet winter thus far (at least for North American lines), even with ports like St. Thomas welcoming upwards of five cruise ships daily full of potentially germy people.

One caveat: Keep in mind that the size of a ship is an important factor in what's considered an "outbreak"; on Oasis, at the abovementioned capacity for guests and crew, the CDC wouldn't get involved unless at least 161 people reported symptoms. But on Noordam, which carries 2,718 passengers and crew at double occupancy, 54 people ill -- just 6 more than Oasis' tally -- meets the two percent threshold.

The bottom line? Noro seriously stinks, whatever the season or ship, and whether you are the only one affected or one of many. So, what do you need to know about the illness and how to avoid it? Read our Norovirus: What You Need to Know and Demystifying the Myths of Norovirus.

--by Melissa Paloti, Managing Editor