We already know cruise ships are susceptible to norovirus, just as any place where people tend to share restrooms and dining spaces such as schools and senior centers. However, since the CDC particularly monitors norovirus outbreaks on cruise ships, cruise lines have become especially vigilant in fighting the spread of the virus onboard. This has proven to be most efficient on newer ships that have completely hands-free restroom facilities and serving stations in the Lido-style restaurants as opposed to long buffet lines where people share serving utensils.
There is some immunity once a person has one bout of norovirus, as long as it is the same strain. The problem is that the virus mutates regularly. It is transmitted by person to person contact, or by touching a surface where an infected person has left the virus behind. It cannot grow on such surfaces, but it can live for short periods of time.
If you are on a sick ship, the key to staying well is to wash your hands regularly, do not rely solely upon hand sanitizers although they are better than nothing. Never shake hands, and try to avoid hand rails and other commonly touched surfaces. If you use an elevator you must use the buttons, so remember never to rub your eyes or nose until you can wash your hands. The virus is spread through stool and vomit, so it the primary responsibility of each individual to keep themselves clean and to avoid actions that may spread the virus even if you feel well. The symptoms may not appear for 24 for 48 hours after infection (they can start in as little as 12 hours), so you may be contagious and not realize it.
Norovirus is known to become more prevalent in the months of February and March, and 2010 has borne this out. Unfortunately there are no cures for the virus but you can treat the symptoms with Kaopectate or Milk of Magnesia. It is a miserable sickness but fortunately does not last long - usually only about 48 hours.
This does not mean the virus will disappear from a ship within that time span, however, because it lives on by transmission from person to person. When Celebrity Mercury had an outbreak affecting nearly 20% of the shipboard population the first week of March the line took extraordinary measures to clean the ship once it returned to its home port, delaying the launch of its next cruise until 8:00 pm.
Norovirus outbreaks are best treated by sufficient heating or chlorine-based disinfectants, but the virus is less susceptible to alcohols and detergents as it does not have a lipid envelope. This means the virus is harder to kill with hand sanitizers, especially the kind that do not involve wiping the hands when you are finished applying them. While washing your hands will not kill the virus, it can remove it from the surface of your hands as long as you wash, rinse and dry thoroughly.
Unfortunately, the thorough cleaning of Mercury was not enough to prevent a subsequent outbreak on the following cruise, although affecting a much smaller number of people. It should not be automatically assumed it lives on through crewmembers onboard, however, as it has been shown that sick ships often sail from sick ports, and the virus could have been reintroduced by a new passenger bringing the virus onboard.
In any case - if you are on a sick ship, or a ship that was recently sick - avoid public restrooms, be careful about washing your hands, avoid touching your eyes, nose and mouth, and restrain yourself from touching commonly touched surfaces such as railings, elevator buttons and serving utensils. And if you see anyone reaching into a plate of food with their bare hands give them your absolute best scowl.
Anytime you are on any ship it is a good idea to practice these same techniques, although the same amount of vigilance is not required. I have personally found that not rubbing my eyes or face and avoiding touching common surfaces - along with frequent hand-washing - has kept me norovirus free for years now throughout dozens of cruises. The last time I got a virus on a cruise ship was in 1999.