Noro virus has been around for a VERY long time and is the second most common communicable virus with the common cold being number one.
On land it is known as "The 24 Hour Flu", "Stomach Flu" or often misdiagnosed as food poisoning. It is very common and is the greatest cause for missed work and school. Nursing homes, schools, workplaces, prisons and anywhere that is a closed environment is a perfect place for spreading of the virus. It is a contact virus that is passed by touching surfaces that an infected person has touched and then touching mucous membranes such as eyes, nose or mouth. The good part is that, in most people, it only lasts 24 to 48 hours and is not life threatening. It can be life threatening in people with compromised immune systems or other health issues.
Feces and vomit is where the virus lives and it is imperative that everyone practices good hygiene including hand washing to avoid contracting and spreading the disease. Basically, wash your hands often and especially after touching common contact surfaces such as handrails, elevator buttons, etc..
So: Wash your hands often and enjoy the cruise.