Numerous newspapers have been reporting that cruise ships operated by Princess Cruises and Royal Caribbean International experienced gastrointestinal (GI) outbreaks in the last week. The Centers for Disease Control and Prevention (CDC) initially reported that norovirus outbreaks sickened over three percent of the passengers on both the Sapphire Princess, operated by Princess, and the Radiance of the Seas, operated by Royal Caribbean, with the predominant symptoms being diarrhea and vomiting.

The CDC reported last week that the total number of passengers on the Sapphire Princess who reported ill were 94 of 2,532 (3.71%); with 67 of 1,993 (3.36%) guests sickened on the Radiance of the Seas. The CDC also reported that 20 crew members on the Sapphire Princess and 2 ship employees in the Radiance of the Seas have been affected.

Today, the CDC is reporting that the number of sick passengers on the Sapphire Princess increased from 94 to 115 of 2,532 (4.54%) and the number of ill crew members increased from 20 to 28 of 1,066 (2.62%).

The outbreak on the Sapphire Princess is taking place on a 32 day cruise from Los Angeles to Hawaii, Samoa, Fiji and the Polynesian islands which ends in Los Angeles on May 7th. Since the cruise is currently underway, it is possible that additional passengers and ship employees may report ill to the ship infirmary.

The outbreak on the Radiance of the Seas occurred during a two week cruise from Tampa to Los Angeles which ended on April 22nd. The Royal Caribbean ship is now sailing an itinerary from Vancouver to Alaska.

The CDC reports that the disease outbreaks on these two ships was caused by norovirus, which typically is the result of contaminated food and/or water according to both the CDC and the Food and Drug Administration (FDA).

This is the sixth GI outbreak over the last four months on a cruise ship returning to a U.S. port this year. Five of the outbreaks were caused by norovirus. Sixteen (16) of the last seventeen (17) GI outbreaks on cruise ships, dating back to the beginning of last year, were due to norovirus (with one case attributable to Salmonella and E. coli). 

Norovirus can also be easily spread through airborne transmission which can further complicate matters on cruise ships. Washing your hands is of little to no effectiveness if the method of transmission is via contaminated food from the galley which is further spread in the air in crowded quarters.

One of the shortcomings of the CDC’s Vessel Sanitation Program (VSP) is that the CDC does not make an effort to determine how GI outbreak occur. The CDC does not make factual, scientific determinations regarding the actual source of the disease transmission (i.e., a particular type of food and/or water and the location of the initial outbreak). This is probably due to the limited resources of the CDC and the quick turn around of cruise ships in U.S. ports.

The cruise industry has no interest in actually determining why a specific outbreak takes place. Most cruise lines will always claim that a guest brought the virus aboard the ship and other passengers then failed to wash their hands. Neither the CDC nor cruise lines investigate whether galley staff and/or food handlers were working while infected. There is no analysis what the passengers, who became ill, last ate or were served during the same seating and/or by the same waiters. There is no tracking by cruise lines of illnesses due to the type of food served during the cruise. This is to be sharply contrasted with shore-side major restaurant businesses in the U.S. when a disease outbreak occurs. Chipotle, for example, has a reputation of determining the specific source of an norovirus outbreak and then focusing on the distributor which supplied the particular contaminated sprouts, lettuce or other food item.

Interested in this issue? We suggest reading the article After Years of Decline, Norovirus Outbreaks Surge on Cruise Ships and our article about a GI outbreak on another Princess cruise ship, the Ruby Princess, a little over a year ago:

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Image Credit: Gastroenteritis viruses – Graham Beards wikipedia / creative commons CC 3.0; Royal Caribbean’s Radiance of the SeasFletcher6 – CC BY-SA 3.0 commons / wikimedia; and Princess Cruises’ Sapphire PrincessPjotr Mahhonin – CC BY-SA 4.0 commons / wikimedia.