A sickly stowaway

As the long summer evenings fade, our collective consciousness inexorably turns towards the winter holiday season. But while most of us will associate the forthcoming months with a long, slow trudge towards the promised land of mince pies, mulled wine and terrible Christmas cracker puns, they embody something quite different for cruise ship medical staff. For them, the countdown to the dreaded norovirus, known colloquially as the 'winter vomiting bug', has begun.

Second only to the common cold in its prevalence, norovirus is characterised by abdominal pain, diarrhoea, vomiting and nausea, and also causes muscle aches, weakness, coughs, headaches and low-grade fevers. Easily passed on through human touch, contaminated food and water, or infected surfaces, the close confines and shared facilities of cruise ships are the ideal breeding ground for this debilitating disease.

Sickness at sea

Over the years, it has caused a slew of PR nightmares for the cruise sector, the scale and horror of which have frequently attracted the attention of the national press. One of last year's worst incidents occurred on P&O Cruises' Orianna in December, when 300 passengers were taken ill during a tour of Europe's Christmas markets.

The shocking reports described people being sick in the ship's cinema, restaurants and corridors, queuing for hours to see the ship's doctor and being forced to endure the smell of vomit below deck. When the ship finally returned to Southampton, refunds were demanded and there were even threats of a passenger sit-in protest.

Cunard's Queen Mary 2 and Princess Cruise's Emerald Princess also suffered outbreaks in the same month, with each ship recording 194 and 189 norovirus victims respectively. And in March this year - marking the tail end of the season - the same fate befell Royal Caribbean's Vision of the Seas. Forced to return to Port Everglades in Florida, more than 100 of the ship's passengers and three crew members were reportedly taken ill.

Yet while such horror stories convey a somewhat doom-laden image of cruise ship health and hygiene standards, the reality is that the sector handles the issue remarkably well, as the following statistics from CLIA reveal:

"Approximately 10.1 million passengers embarked on a CLIA cruise ship from a US port in 2012. There were 16 norovirus outbreaks reported to the Centers for Disease Control and Prevention (CDC), involving a total of 2,791 passengers. This figure represents approximately 0.028% of passengers."

The industry's success in dealing with norovirus is largely a result of the extensive measures put in place to fight the disease.

Fighting back

The struggle began in earnest in the early 1970s with the creation of the Vessel Sanitation Programme. Aiming to define best practices for public health on board cruise ships, it covered gastrointestinal illness surveillance, and to this day requires every cruise vessel entering the US to undergo unannounced inspections twice a year.

Many other countries and continents, including Europe, Brazil, Australia, Canada and New Zealand, also have their own hygiene inspection legislation, meaning that - depending on its route - a cruise ship may be subject to a number of spot checks throughout the year.

While a vital part of the wider solution, unannounced hygiene inspections are in fact only a small part of the industry's broader attack on the norovirus. In more recent years, a far more specific and hands-on approach has been adopted by the major cruise companies, as Dr Grant Tarling, senior vice-president and chief medical officer for Princess Cruises, explains.

"Norovirus is generally introduced on board cruise ships by arriving passengers, so our screening processes start at embarkation," he says. "Every passenger and crew member is required to complete a pre-boarding public health questionnaire, which asks them about symptoms related to norovirus so that we can start tracking it the moment people are on board.

"We also have a rigorous cleaning and disinfection programme that runs continually throughout the cruise. It uses a disinfectant that is not only non-toxic, but also rapidly kills norovirus. Moreover, we have a range of educational materials, such as hand hygiene videos, which are shown regularly throughout the ships.

There are also hand-washing notices and supplemental alcohol hand gels for passengers to use when they're eating in food outlets."

If, however, these precautionary measures fail and the virus begins to spread, there are clear guidelines for crews to follow. Laid out by CLIA in the Guidance for the Management of Norovirus Infection in Cruise Ships, they strongly advocate the use of quarantine for all those infected.

Food handlers and medical staff are required to remain in isolation for 48 hours following resolution of symptoms, while all passengers diagnosed are requested to remain in their cabins for a minimum of 24 hours after feeling well again, and will be barred from buffet areas until asymptomatic for 48 hours.

"The cruise industry has very robust outbreak prevention and response plans," Tarling comments. "They dictate when the ship goes to elevated levels of cleaning and sanitising, depending on the number of cases of gastroenteritis that occur during the voyage. We're very proud of these procedures; in fact, they've been adopted as best practices by many shoreside facilities."

Indeed, the seriousness with which the sector takes the norovirus problem has led to its advice and information frequently being sought by other medical authorities. Reporting all cases to the CDC, cruise vessels are often used as sentinels to inform local and state authorities of land-based outbreaks, helping to identify and resolve issues before they become major epidemics.

Despite the extraordinary lengths the sector has gone to in combating the spread of gastroenteritis, cruise ships are not, of course, solely set up to fight this single disease. As Tarling comments, "The medical conditions we see are no different from that on a shore-based practice. We see the full spectrum of illnesses.

"The cruise industry has, for example, developed rigorous response and surveillance plans for influenza tracking. So when the pandemic H1N1 was evolving worldwide, for instance, we worked with a variety of international health agencies to develop standards and practices on board the ships that would not only track illness but also contain it."

It may be impossible for the industry to completely eradicate gastroenteritis, but the medical zeal on display across the sector, combined with the string of preventative and response measures, will mean that norovirus should find it very difficult to stow away aboard a cruise ship this winter.