The word “quarantine,” comes from the Italian phrase quarantina giorni, ‘forty days.’ It referred to the fourteenth century regulation in Venice that required ships arriving from plague-infested countries to keep their distance from the port for forty days. As the Black Death claimed about fifteen million lives in Europe, the Venetian concern was quite well founded.
Why forty? It does seem arbitrary, and I doubt that in the mid-fourteenth century this was based on epidemiological studies. Was the number forty chosen in keeping with biblical references? After all, the Great Deluge brought forty days and nights of non-stop rain, the Israelites wandered in the Wilderness of Sin for forty years, Moses spent forty days on Mount Sinai, and Jesus fasted for forty days before Satan tried to tempt Him. Perhaps the Venetians thought that such an important number was appropriate for a plague of biblical proportions.
In modern times the duration of quarantine varies according to the specific disease. The recommendation for persons returning from areas stricken with the Ebola epidemic is to stay in quarantine for 21 days. This duration is based on the longest known incubation period for Ebola. How the quarantine is to be enforced has proven to be a highly contentious issue, based on recent news reports. Just today, Kaci Hickox, the Doctors Without Borders nurse-volunteer who recently returned from Sierra Leone, defied Maine authorities by going on a bike ride and breaking the 21-day quarantine imposed by the state.
In a completely unscientific and informal poll, I asked my physician colleagues if the government should subject medical volunteers to a mandatory quarantine when they arrive from Ebola epidemic regions. There were 45 anonymous respondents, and the results were lopsided: 91% answered yes, 9% said no.
Here are the other ‘quarantinable’ communicable diseases as listed in Executive Order 13295 dated April 4, 2003:
- Infectious Tuberculosis
- Yellow Fever
- Viral Hemorrhagic Fevers (Lassa, Marburg, Crimean-Congo, South American, Ebola, and others not yet isolated or named)
- SARS (Severe Acute Respiratory Syndrome)
- Flu that can cause a pandemic