Norovirus Outbreak
Royal Caribbean Cruise Lines - Explorer Of The Seas
February 28, 2006
In what seemed like two isolated incidents, the Explorer Of The Seas was racking up Norovirus victims, for months, and passengers no idea they were boarding a sick ship, voyage after voyage.
The CDC report on the incident give us hints of really happened.
On February 28, 2006, Royal Caribbean Cruise Line contacted CDC’s Vessel Sanitation Program (VSP) staff to report that an elevated number of Explorer of the Seas passengers and crew were experiencing symptoms that were consistent with acute gastroenteritis.
On March 5, the ship’s medical staff reported that 19 of 1184 (1.6%) crew were and 243 of 3245 (7.5%) passengers were ill. The predominant symptoms were diarrhea and vomiting. Stool specimens were collected and tested positive for norovirus.
On March 5, CDC staff boarded the ship in Miami to conduct an onboard environmental and epidemiological investigation, consult with onboard medical staff, observe cleaning and disinfection procedures, distribute crew and passenger surveys, and make recommendations.
The ship's staff continued it's increased cleaning and disinfection procedures, to monitor reports of illness, and provide daily updates to CDC. The number of ill passengers and crew and returned to expected levels two voyages later (sailing dates: 3/12/2006-3/19/2006). The illness returned to expected levels on the following voyage.
The CDC next notes the an incident that begins on April 23.
Royal Caribbean Cruise Line reported an increased number of cases of gastrointestinal (GI) illness on the cruise ship, Explorer of the Seas, for the 7 day voyage completed on April 30, 2006, (sailing dates: 4/23/2006-4/30/2006) in Miami, FL.
On April 28th, 2006, Royal Caribbean Cruise Line contacted CDC’s Vessel Sanitation Program (VSP) staff to report that an elevated number of Explorer of the Seas passengers and crew were experiencing symptoms that were consistent with acute gastroenteritis.
On April 30th, the ship’s medical staff reported that 15 of 1188 (1.26%) crew were and 117 of 3292 (3.6%) passengers were ill. The predominant symptoms were diarrhea and vomiting.
The ship's staff increased cleaning and disinfection procedures, continued to monitor reports of illness, and provide daily updates to CDC until the number of ill people returned to expected levels (the voyage ending on 5/7/06. Stool specimens were collected and results were positive for norovirus.
Because infected ships don't just become clean after the passengers leave and the ship is sanitized, outbreaks begin slowly to a peak, then generally decline.
However, the common thread in any outbreak on a ship, that continues for more than one voyage is the crew. They stay aboard and continue to spread the infection.
The CDC reports show this outbreak, at minimum ran from February 28, 2006 through May 7, 2006, a period of ten weeks. While we can only guess at the total numbers of those who reported to the infirmary, and can't begin to guess how many were infected, if those who did not seek medical care aboard were included, we do know this single outbreak, over many cruises racked up at least 394 victims.
NOTE: Cases reported in this category only reflect those reported to the infirmary. Many passengers do not seek medical care aboard a ship, due to the high expense.
