It is no doubt not a record that Royal Caribbean would have aspired to. Their ship, Explorer of the Seas, on its voyage from New York harbor to the Eastern Caribbean, from January 21-29, 2014, had the largest outbreak of gastro-intestinal sickness among the passengers and crew than on any other cruise ship for as long as the Center for Disease Control (CDC) has been keeping records of such things. Almost 700 of the passengers and crew became ill on the cruise. Testing has not been completed, so there is no determination that the outbreak was a norovirus, but all symptoms suggest that a norovirus was the culprit which sickened so many.

According to the CDC, 684 passengers and crew were stricken by illness.  Of these 630 of the 3,071 passengers were made ill, or 20.5%. Of 1,166 members of the crew, 54 became ill, or 4.6%.   The CDC considers any outbreak over 2% of the passengers and crew to be serious enough to require a special notification.  The CDC posts details on their website of any outbreak representing over 3% of the passengers and crew.

Not all outbreaks are posted.  When the Royal Caribbean Majesty of the Seas called in Miami two weeks ago, 68 passengers and crew were sick with what is believed to be a norovirus, but don’t appear in the listing as the numbers do not quite hit 3%.

Time Magazine has tabulated the 13 worst norovirus outbreaks on that have taken place on cruise ships.  Compared to past outbreaks, that on the Explorer of the Seas was over 40% larger than the next highest, on Celebrity Cruise’s Mercury in 2010.

Celebrity is also a subsidiary of Royal Caribbean.  Royal Caribbean is, however,  by no means the only major cruise line with a norovirus problem.   Six of the top thirteen outbreaks as tabulated by Time were on ships owned by Carnival or its subsidiaries.

The number of ships struck by norovirus outbreaks as listed by the CDC, actually declined in 2013, to nine, as compared to sixteen ships in 2012,  twenty two ships in 2006 and thirty five ships in 2005.

Cruise Out of Control: The 13 Worst Norovirus Outbreaks on Cruise Ships