A gastrointestinal (GI) outbreak of unknown origin occurred during a cruise to Alaska last week on the Carnival Splendor cruise ship which sickened ninety-three (93) passengers and crew members.

According to the Centers for Disease Control and Prevention (CDC), 77 of 2,109 (3.65%) guests and 16 of 1,079 (1.48%) crew members reported being ill during the cruise from Seattle to Alaska on March 24 to March 31, 2022. The predominant symptoms of those infected  were “vomiting and diarrhea.”

In about a quarter of the cruise ship disease outbreaks reported to the CDC, the federal health agency is unable to determine the cause of the sicknesses. This year, the CDC has been unable to determine the cause of the two GI outbreaks which occurred – this outbreak and the outbreak on the Seabourn Odyssey from April 28th through May 19th which sickened 15 of 380 (3.95%) passengers and 5 of 347 (1.44%) crew members.

In 2019, there were ten disease outbreaks on cruise ships, with the CDC unable to determine the type of disease involved in two of these cases. In 2018, there were eleven outbreaks, with the CDC unable to determine what the CDC calls the “causative agent” on four occasions. In 2017, the CDC could not determine the cause of one out of eleven cruise ship outbreaks. The CDC information has been publicly available for the past twenty-eigth years.

The most common cause of ship disease outbreaks is norovirus. Other exotoc-sounding diseases include Vibrio, Enterotoxigenic E. coli (ETEC), Campylobacteror and C. Perfringens Enterotoxin.

The detailed conclusions regarding the number of sickened guests and crew members in GI outbreaks are in stark contrast to the CDC’s policy of reporting COVID-19 outbreaks where the CDC does not disclose the number of either infected passengers or crew members.  This may please the cruise lines, which refuse to disclose such statistics, but it is a real disservice to the public which deserves to know the truth.

It is outragous that the cruise lines and the CDC keep this fundamental information about COVID-19 outbreaks secret. We have seen situations where there may be literally only five or six COVID-19 cases on some cruises, but as many as over two hundred cases on another ship. Yesterday, for example, we received an inquiry from a guest who recently cruised on the Caribbean Princess, where she contracted Covid. There was no official announcement by the cruise line of the number of people affected, although the scuttlebutt on the ship was that the ship was “inundated with cases.“ She stumbled on this blog looking for sources of information about the COVID-19 outbreak on the Princess cruise ship which had sickened her.

Guests infected during a cruise or deciding whether it’s safe or prudent to take a cruise on a particular cruise ship which just had an outbreak, should be able to go to an official source for accurate information. They should not have to scour the internet search through cruise chat rooms trying to find out basic public health information already reported by a cruise line to a federal health agency but not disclosed to the public.

The U.S. public pays for the services of the CDC and deserves transparency. The last thing the public needs is for the CDC to act like a non-transparent cruise line (which pays no U.S. income taxes because of its foreign incorporation and registration of its ships outside of the U.S.) and keep such public health hazards secret.

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Image credit: Carnival Splendor – Sparrowman980 at English Wikipedia, CC BY-SA 3.0, commons / wikimedia.