Starting in the 1370s, all ships wanting to enter Venice had to wait on the nearby island of San Lazzaro until the health magistrates granted the crew permission to disembark. Over time, the waiting period became standardized at forty days—the word quarantine is derived from quaranta, the Italian for forty.
Its strange that this is the only example so far of a city taking active measures. It is interesting that we derive the word "quarantine" from quaranta - 40 days seems sufficent to see if incoming vessels harbor diseas. However, the waiting period may slow business...
