Passengers who became ill on board the Aurora may not succeed in their claims. Tim Oliver and Penny Lewis explain

The events aboard the cruise liner Aurora last week looked like bad news for the insurance industry. Hundreds of passengers talked about claiming against the ship's operator P&O and its insurers. But is P&O liable?

Norwalk, the virus contracted by the passengers, is a highly infectious, common infection responsible for many epidemics of non-bacterial gastroenteritis in developed countries. It is believed to be spread by 'faecal-oral route' and 'transmission vehicles' include oysters and salad. It is frequently associated with epidemics in institutional environments such as nursing homes and hospitals. This virulent infection is named after an outbreak in Ohio. Because it is a short-lived virus, outbreaks tend to occur in confined areas, such as hotels. Victims suffer copy-cat symptoms.

Norwalk is similar to that other airborne nuisance, the common cold. There is no vaccine or long term immunity. Incubation periods are 18-72 hours and it is usually mild and self-limiting, lasting one to two days. The very young, old, pregnant or ill are more susceptible to nasty complications; and fatality is extremely rare.

So, is anyone at fault when it is caught? Unless it was obvious that a boarding passenger was ill it is hard to see how a ship could be responsible for a spreading virus any more than bus companies are when someone with a cold gets on a bus.

On a boat or plane it is also understandable to associate vomiting with travel sickness although carriers must clean up the mess efficiently. One contaminated handle can do a lot of damage.

Examination of these cases will probably consider if there had been earlier incidents. The survival time of the virus is unknown but a history of outbreaks in one place would be relevant. Hygiene in food preparation and cleanliness are factors in prevention and containment. Therefore, prompt and thorough cleaning is vital.

In practice, tough, there is unlikely to be any foolproof means of stopping Norwalk on a ship short of disembarking everyone and disinfecting every inch.

Whether illness was introduced by a crewmember is important too.

So what redress is there? Under the Package Travel, Package Holidays and Package Tours Regulations [1992], absent negligence by tour operators or their suppliers, package travellers may not have legal entitlement to compensation.

Circumstances neither foreseeable nor beyond one's control do not make good claims. Goodwill payments are different. As with the Sars epidemic and subject to individual conditions of travel, it would be difficult to cancel planned holidays unless there is evidence that your health would be at risk.

Tim Oliver and Penny Lewis are with Plexus Law