According to a report by the Associated Press (AP), over 200 passengers on the Norwegian Cruise Line ship Pride of Hawaii that sailed around the Hawaiian islands last week were infected with norovirus, a highly contagious stomach flu.

A spokeswoman for the Hawaii Department of Health, Janet Okubo, told AP that the lab tests confirmed the infection was caused by norovirus.

The ship docked back in port in Honolulu on Monday after completing its weekly seven day cruise of the islands. There were 2,500 passengers on board, and just under 10 per cent of them became infected. Nobody needed to go to the hospital and the symptoms were mostly gone after 24 hours.

The US Food and Drug Administration is still investigating the outbreak.

Okubo said most of the time people recover from norovirus, and it was one of the common ones they saw on cruise ships.

Norwegian told AP that it had compensated passengers who got sick with on-ship credit vouchers and that all surfaces had been cleaned to remove any remaining traces of the virus.

According to the US Centers for Disease Control and Prevention (CDC) norovirus, originally called Norwalk-Like Virus (NLV), is the most common cause of non-bacterial gastrointestinal infections (“stomach flu”, or gastroenteritis) in the USA.

Symptoms include stomach pain, diarrhea, vomiting, and feeling weak or lethargic.

Neglecting to wash hands and to clean and disinfect kitchens and restrooms frequently and thoroughly are among the reasons that outbreaks occur.

Norovirus is common where there are lots of people in semi-enclosed spaces, such as nursing homes, schools, cruise ships and hospitals.

Although it is called stomach flu, norovirus is not related to the flu which is a respiratory illness caused by the influenza virus.

The illness lasts for one or two days and people can feel very sick and vomit frequently during this time. However, the majority get better after a day or so and have no long term effects.

Problems can occur when people don’t replace enough of the fluid they have lost from vomiting and diarrhea. They will need medical help to treat dehydration. This usually affects the very young, the elderly, and those with weakened immune systems.

Norovirus is actually a group of viruses of which there are at least five genogroups: GI, GII, GIII, GIV and GV, and each group has at least 30 subgroups.

The virus is transmitted mainly via the fecal-oral route, usually by consuming contaminated food or water or from touching another infected person. Touching contaminated surfaces can also spread the virus.

There is no evidence that the virus spreads through the respiratory system; it is most likely ingested through the nose or mouth from touching an infection source and then putting the hand near the nose or mouth, or from aerosol droplets from an infected person entering the oral route of another.

The virus is highly contagious: as few as 10 viral particles can be enough to cause a person to become infected.

Cruise companies have been improving their procedures for monitoring and dealing with norovirus infections. For instance, one company, Carnival Cruises, has trained its staff to look for signs of illness in passengers at embarkation.

Steve Williams, director of medical operations for Carnival Cruises, said in an interview with World Cruise Network recently that:

“Every month we have to deny boarding to one or two people because of illness, but we give them a 100 per cent refund on their cruise.”

“It’s a sacrifice worth making,” he added, “Carnival’s ship Liberty was hit by the virus in 2006, and nearly 700 passengers and crew became ill during an Atlantic crossing after infected guests boarded in Rome”.

Another company, Celebrity Cruises, started compiling its outbreak plan in 2002, after a comprehensive review of procedures following a series of outbreaks.

Manny Rivas, public health assurance manager for the company, told World Cruise Network that Celebrity Cruises’ procedures manual was “put together based on our best practice and recommendations from medical experts and the CDC”.

Their system works on three codes: green is standard procedures, with routine cleaning twice a day of frequently touched areas such as lift buttons and handrails. If 0.5 per cent of guests get sick, the code goes to yellow, with cleaning frequency and intensity going up to 4 times a day, and they step up announcements and advice to passengers.

A code red would be triggered if 1.5 per cent of passengers got sick said Rivas, and then there is a marked change in ship procedures:

“We stop the self-service food, sanitation teams clean between sittings and we aim to clean the public areas every half hour.”

During code red, passengers are shown a ten minute video on hygiene and medical facilities that runs continuously on a loop in the public areas, hand shaking is discouraged, and the captain also makes a daily announcement, said Rivas.

Click here for World Cruise Network article and interviews on dealing with outbreaks on cruise ships.

Click here for more information about norovirus (CDC, US).

Written by: Catharine Paddock