If you're among our French speaking readers, you may notice a more-than-passing resemblance between this week's word and the French word for forty, quarante. The resemblance is no accident, and can be traced back to mediaeval Venice and, possibly, other cities as well.
One of Europe's busiest ports at a time when the plague was in full swing, Venice was especially susceptible to outbreaks of the disease. To manage the risk, the city fathers insisted that any ship arriving from a plague-stricken country should wait offshore for quarantina giorni - literally a period of 40 days - enough time for any latent disease to have revealed itself in a full blown, ship-only, outbreak.
By the 1670s, quarantine had expanded in meaning to encompass any period of enforced isolation used to manage people or animals who might have been exposed to disease.
One of the first documents describing the practice comes from 1377 Dubrovnik, where the period of isolation was not 40 days, but 30 - a trentine. One assumes that bitter experience led to the 10-day extension and resulting name upgrade.
Mary Mallon, aka Typhoid Mary, is a particularly sad case of someone subject to quarantine. Born in 1869, she was identified as the source of at least two major typhoid outbreaks and was quarantined twice. Her second quarantine lasted from 1915 to her death in 1938, a period of nearly 24 years.