The word "quarantine" originates from quarantino, the Venetian dialect form of the Italian quaranta giorni, meaning "forty days".

This is due to the forty-day isolation of ships and people practiced as a measure of disease prevention related to the plague.

Between 1348 and 1359, the Black Death had wiped out an estimated thirty percent of Europe's population, and a significant percentage of Asia's population.

Such a disaster led governments to establish measures of containment to handle recurrent epidemics.

A document from 1377 states that before entering the city-state of Ragusa (modern Dubrovnik in Croatia), newcomers had to spend thirty days (a trentine) in a restricted place (originally nearby islands) waiting to see whether the symptoms of Black Death would develop.

In 1448 the Venetian Senate prolongs the waiting period to forty days, thus giving birth to the term "quarantine".

The forty-day quarantine will prove to be an effective formula for handling outbreaks of the plague.

According to current estimates, the bubonic plague had a thirty-seven-day period from infection to death; therefore, the European quarantines would have been highly successful in determining the health of crews from potential trading and supply ships.