Norovirus outbreaks on American cruise ships

Not much was known about a single-stranded RNA virus called Norwalk-like virus (after an outbreak of gastroenteritis in Norwalk, Ohio in 1968) about 20 years ago, other than that it was able to cause a diarrhoeal illness. We call this group of viruses Norovirus today, and it is actually now known to be the leading cause of gastroenteritis in the USA.
Most cases of Norovirus infection occur in winter months, and what makes this particular virus so dangerous, is its unbelievable contagiousness, and the fact that it is very environmentally robust (not like HIV, for example). People may shed (and thereby pass on) Noro from the beginning of symptoms to weeks after symptoms have stopped. It is mainly transmitted via the fecal-oral route, through contaminted food or water, or by touching contaminated surfaces. There is also evidence that droplets from vomiting can be picked up by persons touching such surfaces where droplets have landed. Because it is so highly contagious, outbreaks tend to occur in confined spaces such as nursing homes, or cruise ships. There are currently 3 American cruise ships where large numbers of passengers and staff are ill from Norovirus infection.
This is what the thing looks like under an electron microscope :

The way Norovirus works is that it has an extremely short incubation period of only (12-)24-48 hours, and the symptoms are caused by the virus infecting the inner lining of the stomach and subsequently the gut, leading to an inflammatory response by the body, causing first nausea and frequent vomiting, and then watery diarrhoea and abdominal cramps. Symptoms last between one and three days, and recovery is almost always complete. What is a bit mean is that infection seems to give no long-lasting immunity, so people can get infected repeatedly during their lifetime.
Norovirus can be diagnosed in the lab by what’s called a reverse transcriptase PCR, but often the clinical scenario is enough to suspect Noro as the culprit, as is the case on those cruise ships in the US at the moment.
As with most virus infections, there is no specific therapy. Drugs like Buscopan may relieve cramping, but more important is to avoid dehydration by keeping oral fluids up as best as possible. Of utmost importance is the minimization of virus spread. Affected persons should use their own toilet, handwashing with soap is mandatory, and all potentially contaminated surfaces must be cleaned with suitable disinfectant cleaners.

I tell you what, should I ever go on a cruise, no shrimp salad for me.