The Centers for Disease Control (CDC) reports that 10% of the passengers aboard Holland America Line's Amsterdam cruise ship were sickened by a disease on the ship. It is not yet known whether the disease was norovirus or due to some other causative agent.
The Amsterdam was in port in San Diego yesterday after a long cruise starting in Sydney Australia on November 11 and arriving in San Diego on December 5, 2012. 81 of 791 passengers became ill. This turns out to be 10.24% of all passengers (assuming all passengers reported their illness and the cruise line accurately reported the outbreak to the CDC). This is an extremely high percentage of affected passengers.
The cruise line's PR department down-played the outbreak saying "a number of guests reported to the infirmary with a common type of gastrointestinal illness." The popular cruise site Cruise Critic (owned by Expedia travel company) shrugged the illness off as due to a "stomach bug" and repeated HAL's advice to passengers for "extra hand washing."
As usual, there is no discussion regarding the most likely cause of the outbreak. Cruise lines like HAL like to blame the passengers and suggest that they brought the virus aboard and it was then spread because other passengers didn't wash their hands. If this is viral based, due to norovirus, or due to e-coli infection, the real culprit is probably contaminated food or water.
According to the U.S. Food and Drug Administration (FDA), whereas "person to person" transmission of norovirus has been documented, "norwalk gastroenteritis is transmitted by the fecal-oral route via contaminated water and foods." The FDA indicates that contaminated water is one of the most likely causes of norovirus. The FDA reports that "water is the most common source of outbreaks and may include water from municipal supplies, well, recreational lakes, swimming pools, and water stored aboard cruise ships."
Most of the affected passengers reportedly became symptomatic after the cruise ship left its last port of call (Hilo, Hawaii) on November 29th. Are we to believe that suddenly 10% of the passengers suddenly stopped washing their hands? Or is it more likely that contaminated food or water introduced at the last port of call were the culprit?
The Friends of the Environment (FOE) has an interesting article that the problem is not sick passengers affecting the cruise ship, but sick ships affecting the passengers. FOE tracked the top 12 cruise ships with the most gastrointestinal outbreaks from 2000 to the present, based on the CDC data.
Out of the top 12 sickest ships, HAL operates 5 of them and has the top three sickest ships. HAL's Amsterdam is number 2. The Ryndam is number 1. The Veendam, which recently flunked a CDC health inspection (you can read about the filthy ship here and here), is number 3. The other HAL cruise ships which made the top 12 sickest list are the Volendam (no. 9) and the Zaandam (No. 11).
Art credit: Chan Lowe / Sun Sentinel
Chart Credit: Friends of the Earth