Every July in Italy, Venice the Festa del Redentore (Feast of the Redeemer) celebrates the city’s deliverance from the plague, which killed 50,000 people – in Venice – between 1576 and 1577. (A mass grave of victims was dug up five years ago.) That two-year epidemic was one of the many outbreaks that followed the previous century's plague, aka the Black Death, which took an estimated 75-200 million people in Europe from 1346 to 1353.

Plague is still with us. There now is an outbreak in China leading to quarantine of 30,000 and the isolation of victims.

The practice of quarantine being used today developed nearly 500 years ago in Venice as the city attempted to protect itself from the plague. As the Centers for Disease Control and Prevention describes it: "Ships arriving in Venice from infected ports were required to sit at anchor for 40 days before landing. This practice, called quarantine, was derived from the Italian words quaranta giorni, which mean 40 days." The latest quarantine, in Yumen city, Gansu province, was lifted after nine days.

Venetians responded to the plague by building a church, Il Redentore. Today, we use antibiotics. Yes, there are still cases in the United States but, fortunately, very, very few (about seven a year.) The CDC monitors outbreaks of plague and other diseases. The World Health Organization's Global Alert and Response technical consortium monitors other diseases determined to be of international importance.

Countries around the world still rely on quarantine and isolation to stop the spread of certain infectious diseases. As historian David Barnes noted in a recent post, the U.S. has 20 quarantine stations across the county, including one in Terminal A of the Philadelphia International Airport.” Federal authority for operating these stations – and for imposing quarantine and isolation – derives from the Commerce Clause of the United States Constitution. Arrest warrants are issued in rare cases, such as one this week for a man with tuberculosis in California.

A 2007 report by the Trust for America’s Health reported that a majority of those polled stood ready to abide by a voluntary quarantine (in that case for a flu pandemic). Like the citizens of medieval Venice, modern Americans seem to understand that halting contagious diseases requires collective action as well as the care of afflicted individuals.

Read more about The Public's Health.