I want to clear some doubts, about the health standards that cruise companies must comply with, since many people do not dare to take a long cruise, in case something happens to them. The first thing I have to tell you is that there are always doctors on board, and I am not referring to passengers, but to specialized personnel and equipment also according to emergencies. And is that on board a large ship, in addition to the cruise passengers on board, many employees travel who spend long periods on it.
Note that health on cruise ships has very strict regulations, to begin with there are minimum sanitary requirements to operate, the standards are global in scope for sanitation on the high seas and when ships are in port.
There is an established protocol in terms of disease monitoring and response when infections occur, safe food and water supply, management of rodents and disease vectors, and waste disposal. This protocol follows the International Health Regulations, revised in 2005, a legally binding international agreement signed by 196 countries.
As I was saying Cruise ships have a medical center on board with an infirmary, which is 100% equipped for emergencies and cures. But remember that these centers are not intended to treat a pre-existing condition, although some of them do have dialysis centers. What i recommend you if you have a previous ailment it is that you check, and specify your questions well, about your medical needs.
The Spanish National Epidemiology Center has developed a protocol for the mandatory declaration of diseases as it is considered highly contagious, it must be complied with by any ship that docks or leaves a national port, regardless of their nationality.
If you want to have additional information on health and safety on board, I recommend that you read this article.