Why Are There So Many Disease Outbreaks On Cruise Ships?

A recent outbreak of deadly hantavirus, a disease usually spread via rats, has been tied to cruise ship travel by the World Health Organisation.

And France confined over 1,700 people to a cruise ship after a suspected norovirus outbreak occurred on board, though passengers have since been released.

The thought of being stuck on a ship filled with a contaqgious virus is a pretty scary one. But how likely is it?

We asked Professor of Medicine in Norwich Medical School, Prof Paul Hunter (whose research interests include the spread of infectious disease), whether and why cruise ships might be a hotbed for illnesses.

Professor Hunter told HuffPost UK that there’s a long-established link between cruise ships and the spread of infectious disease.

America’s Centre for Disease Control and Prevention (CDC) Yellow Book said the form of travel “presents a unique combination of health concerns”.

Most commonly, Prof Hunter said, these diseases include norovirus and the ’flu.

But outbreaks can include “a range of other infectious diseases, including Covid-19, Legionnaires’ disease [a very serious, and sometimes fatal, lung infection] and RSV [respiratory syncytial virus, especially dangerous for babies]”.

“There are many reasons,” Prof Hunter shared.

“First, you bring together a large number of people from all over the world for a period of one or more weeks in an environment that is largely indoors.”

It is easier for many diseases to spread indoors, especially where ventilation is poor.

Then, there’s the fact that most cruise passengers are over 50.

“The average age is often older than the general population, and many people may have a pre-existing medical disease that increases their vulnerability,” said Prof Huntr.

“Some of that population may live relatively socially isolated lives at home, having retired from work, and so have had less of a chance to be exposed to circulating virus infections and so have lower immunity.”

Shore visits can heighten risk, too, as these “may expose people to infections that they then bring back on board”.

Lastly, “Some outbreaks have been due to failures in ship management, such as food poisoning. Faulty plumbing/pool management could lead to Legionnaires’ disease. For example, one outbreak of Legionnaires’ disease was linked to a whirlpool spa.”