Mike is so right. The crew and staff do take an outbreak very seriously. I have been on a couple of ships where there has been an outbreak and luckily we did not get it. But, on a recent cruise I came down with a dreadful cough/sinus infection, slight temperature and because I told the nurse in the Infirmary that I had dirrahea, they quarantined me for 24 hours. Turns out I had bronchitis, but they were taking no chances.
As to the Mother screaming she didn't know where her child was, I am skeptical about this. First of all they quarantine the patient to their cabin and anyone else who is in that cabin. Sounds like the "child" was an adult and they probably didn't want to talk to anyone on the phone or answer the door if the Mother called their cabin..........I know I was so sick all I wanted to do was sleep.
Norovirus is everywhere, not only on ships. It's here in the schools, offices, hospitals, etc. etc. When you get so many people confined to such close quarters, it's very easy to pick it up if you do not take precautions.