Starting on our 5th day of the cruise, my wife was in and out of Deck 1 Medical Facility with an upper respiratory disease that she caught during the cruise (incubation is approximately 3 days) and was treated with antibiotics. That apparently caused her to come down with diverticulitis, which in my wife's case caused severe abdominal pains. Initial pain killers did not work. Finally she was given the good stuff and we made it home, where I immediately dropped her off at our hospital. The doctor kept her for two nights.
I caught the upper respiratory infection after the 7th day on board.
We both used good sanitary procedures throughout the cruise, which apparently was not enough to prevent contact with the carrier person.