Explainer: Why Cruise Ships Harbor Viruses

Copyright © 2009 National Public Radio®. For personal, noncommercial use only. See Terms of Use. For other uses, prior permission required.

MADELEINE BRAND, host:

It seems viruses have a thing for ships. Passengers on luxurious ocean liners are often finding themselves caught up in many epidemics. Just last week the worlds largest cruise ship was hit with a virus that infected 400 passengers.

So, what makes these ships so germy? That is a question for the explainer team at the online magazine Slate. And here with the answer is Slate's Andy Bowers.

ANDY BOWERS: It's the close quarters the virus responsible for the two most recent outbreaks, a form of norovirus, starts out as a food or water contaminant that spreads rapidly from person to person.

With so many people sharing cabins and bathrooms infections are more likely. To make matters worse cruise ships often make stops in countries with questionable food and water safety.

Once an outbreak starts crewmembers might serve as reservoirs for the virus. Ships also take on new passengers every week or two, which makes it easier for a single outbreak to extend across consecutive cruises.

Strict government surveillance and reporting requirements that have been in place since the 1970s make sure that even the smallest outbreaks get noticed. Norovirus outbreaks have also been documented at sporting events. In 1998, both teams in a college football game got sick.

BRAND: Andy Bowers is a senior editor with the online magazine slate, that explainer was compiled by Daniel Lingber(ph).

Copyright ©2009 National Public Radio®. All rights reserved. No quotes from the materials contained herein may be used in any media without attribution to National Public Radio. This transcript is provided for personal, noncommercial use only, pursuant to our Terms of Use. Any other use requires NPR's prior permission. Visit our permissions page for further information.

NPR transcripts are created on a rush deadline by a contractor for NPR, and accuracy and availability may vary. This text may not be in its final form and may be updated or revised in the future. Please be aware that the authoritative record of NPR's programming is the audio.