Quarantine hotels have been around a lot longer than Covid. Credit: JAIME REINA/AFP via Getty Images

During the pandemic, the words “isolation” and “quarantine” have been somewhat elided. But it’s useful to distinguish between them: if you definitely have a disease and you’re kept apart from everyone else, you’re in isolation; if it’s uncertain whether you have a disease but you’re separated for a while just to be safe, you’re in quarantine. The crucial difference is the element of uncertainty in the latter — and it’s this uncertainty that obsesses the authors of a new book about quarantine.
Husband and wife Geoff Manaugh and Nicola Twilley did most of the research for Until Proven Safe before the Covid-19 pandemic struck. Perhaps they felt strangely lucky, then, as the world descended into the current age of lockdowns and self-isolation, their study of “the history and future of quarantine” taking on a sharp new relevance.
Reading the book, there’s a case to be made that the just-to-be-sure quarantining began in fourteenth-century Dubrovnik, where travellers from areas known to be infested with the Black Death weren’t allowed to enter the walled city until they’d spent a month on a nearby small island. Similar schemes were adopted for maritime visitors to Venice, where you can still visit the lazarettos — quarantine hospitals — that were built especially for this purpose. Even lacking the germ theory of disease, the powers-that-be in these ancient cities intuited that separating was a way of protecting.
In the modern era, with a much better understanding of germs, we sometimes quarantine humans when we don’t really believe it’s necessary: recall the famous photo of the Apollo 11 astronauts, having just returned from their successful moon landing, meeting Richard Nixon from behind a window in a sealed metal box. They were quarantined for three weeks just in case they’d brought back some unknown alien pathogen from the moon — even though it was strongly suspected that (as we now know) the surface of the moon was sterile, and no such pathogens existed.
We’ve been less strict when it comes to the animal kingdom, where we can see some of the most drastic consequences of not quarantining playing out. Think of the episode of The Simpsons where Bart sneaks his pet bullfrog into Australia, whereupon it promptly escapes, reproduces, and devastates all the crops in the country. Manaugh and Twilley remind the reader of the UK’s terrible foot-and-mouth disease crisis in 2001, which originated in pigs who had been fed illegally imported pork from Asia. They also describe how Florida’s citrus industry has been in decline for years due in large part to the insect pest known as the psyllid. Only extremely strict quarantine of incoming plants by the state of California has stopped something similar happening to its famous oranges.
And remember the “friendship tree” that Donald Trump and Emmanuel Macron planted on the White House lawn in 2018? Being from France, its roots were specially wrapped in plastic so as not to spread anything nasty to the US — and it was immediately dug up and sent for a two-year quarantine as soon as the cameras were switched off. (In a definitely-not-metaphorical development, it died before it was returned).
It might seem to be stretching the term, but we quarantine some non-living objects, too: containers of radioactive waste are “quarantined” deep underground until they’re no longer dangerous. That, as Manaugh and Twilley explain, might be a very long time — long enough that scientists have tried to develop universal signs and symbols to communicate with civilisations thousands of years in the future who might have languages very different from our own: “there is bad stuff here – it is dangerous”.
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