Norovirus is the second most common virus in the world after the common cold. It is often called "stomach flu" although that is not a specific disease - it is just another way of describing gastrointestinal upsets such as vomiting and diarrhea -- common symptoms of norovirus. It is an unpleasant illness, but it often passes in as little as 24 hours; 72 hours at the most.
Because cruise ships share lots of touchable surfaces; elevator buttons, food service utensils and staircase banisters, for example, it is easy to spread norovirus. But the same is true for schools, hotels, senior centers and office buildings. But those entities are not required to report norovirus outbreaks to the Center for Disease Control (CDC). Only cruise ships are required to report because only cruise ships have the unique ability to contain the virus, making it possible for cruise ships to provide valuable information about norovirus to the CDC.The worst thing about Norovirus is the very easy contagion factor. It can live on surfaces that have been touched by infected people, if those people didn't wash their own body fluids off of their hands. It can even be transmitted by air as long as that air contains live particles, although the virus is not a typical "airborne" disease.
So cruise ships have gotten a bad rap by uninformed people who do not understand that cruise lines report viral outbreaks for the benefit of the CDC, not because they have any unique problem with Norovirus. In 2010, for example, the city of London had a land-based Noro outbreak that infected half a million people in one weekend - no cruise ships within 100 miles.
That being said - yes, you do stand a chance of getting Norovirus on a cruise ship, to the same degree as you do in a shopping mall, senior center or grade school. So let's look at ways to avoid the virus...
Washing your hands with soap and water is the best way to stop the spread. Soap does not kill the virus, but it will dislodge and remove it from your hands.
Avoiding the Norovirus Bug
Noro is unusually infectious. One only needs as few as 10 to 100 flu particles to catch it, where the typical seasonal flu requires about 10,000 particles. The main symptom is vomiting, with diarrhea the secondary one. As a gastrointestinal illness it usually does not cause achy pains or coughing.
Unfortunately, although the cruise lines tend to encourage the use of alcohol-based hand sanitizers onboard, recent studies show that alcohol alone does not kill the virus. But hand sanitizers are better than nothing and most effective when used with an absorbent paper towel.
What If You Catch It?
If you are unfortunate enough to catch Norovirus you will probably know it soon from the gastrointestinal distress. It is important that you isolate yourself from other people for at least 48 hours after your symptoms pass, as you can still spread the virus.
However, as a note of caution, be aware that the cruise lines are particularly sensitive to onboard illnesses. If you go to the ship's doctor complaining of a sore throat or cough he just might order you to stay in your stateroom for a day or two. In extreme cases they can even ask you to leave the ship. So, as much as I dislike the idea of telling people to hide their symptoms, I also don't want to see your vacation ruined unduly.
I encourage you to take personal responsibility for the common good, isolate yourself and keep your hands very clean. But don't tell shipboard personnel that you are sick unless you really need their assistance. You may not be happy with the consequences.
During the cruise check-in process you will be given a questionnaire form asking if you have experienced any specific symptoms within the preceding three days; vomiting, diarrhea, coughing, sore throat, runny nose, etc. This questionnaire is mostly a symbolic measure by the cruise lines, in my opinion, since many of these symptoms can be caused by non-transferable allergies, food poisoning or other reasons.
Technically, if you admit to any of the listed symptoms the cruise line is supposed to give you follow up examination by a doctor or nurse. However, I have been contacted by people who claim they were in good health at check-in but filled in the form, candidly, expecting a follow-up examination. But they were denied their cruise without ever seeing a doctor, nurse or anyone other than security to escort them back to their cars.
I don't know if these stories are true, I only know that form does nothing to help you and can only create problems if taken too seriously by the wrong person. It may or may not disclose this on the form, but if you admit to any symptoms on that form you may be denied boarding the ship with no compensation. Just so you know.