The word quarantine comes from the Venetian word for 14. The number of crew on a Venetian galley was 14 and if a boat arrived with fewer than the full crew, it was assumed that one had died and been thrown overboard to conceal the fact that they might be carrying contagion.

Interestingly this led to some captains setting out with extra crew members. If they arrived all healthy, the extra would be dropped off secretly. You can see them holding special boat number plates hoping for a ride back to port.

As a result the Italian word "pasagio" meaning to give someone a lift, came into English to mean a "passenger" or non crew member.

And also the Italian word peste meaning plague, has come into English as pest, meaning someone you would like to get rid of, dating back to this custom.

If a boat did arrive with the plague, it would be put into "isolamento" from the Italian word for sun so the ultra violet rays could hopefully kill the virus. So perhaps Trump was on to something or had read his medical history.