We’ve Been Disinfecting Mail for Hundreds of Years

As a young boy, Denis Vandervelde realized he faced two major obstacles to achieving distinction in the study of stamps, called philately: he was penniless, and, worse, color-blind. “A lot of the expertise in stamp collecting depends on shades and tiny variations in printings,” he told us. “So it was a daft hobby for me to have.”

Instead, Vandervelde began collecting postmarks and quickly found himself absorbed in an entirely different pursuit—a kind of postal treasure hunt, documenting the elaborate bureaucracy that has emerged to manage the movement of mail around the world. His collection, assembled over nearly 50 years, boasts 3,000 items of disinfected mail: letters that have been punctured, perfumed, or otherwise purified to prevent the transmission of disease. During the coronavirus pandemic, the practice reemerged: Authorities around the world marked letters as delayed in quarantine, envelopes were stamped with fumigation notices, and parcels from suspect countries were returned to sender.

By studying the traces left by disinfection—scorch marks, stains, and incisions—and the distinctive cancellations used to mark mail as treated, Vandervelde and his colleagues in the Disinfected Mail Study Circle, an international group of hobbyists and collectors, have ended up performing a forensic archaeology of quarantine through its postal paper trail. Official medical records from before the 18th century are sparse; disinfected mail inadvertently provides a time-stamped, geotagged archive of past epidemics, while its treatment establishes documentary evidence of both permanent and pop-up systems of infection control.

Until Proven Safe book cover
This post is excerpted from Geoff Manaugh and Nicola Twilley’s new book.

We met in Islington, London, at Stampex, a biannual philatelic fair that is Europe’s largest. Vandervelde, a sprightly octogenarian, suggested that we join him after a morning’s booth-browsing as he refueled with a glass of Shiraz and a pizza at the convention center café. Over lunch, he explained that the practice of disinfecting mail was first formalized in the Adriatic, though no one knows exactly when. Certainly by the 1490s, following a century during which Venice had been scourged by a fresh outbreak of plague every decade, that city’s health authorities had decided that it might be wise to extend their sanitary precautions to letters that came from infected areas. As with many of the other practices of quarantine, including the institution of quarantine stations, known as lazarettos, other port cities were quick to follow in Venice’s footsteps.

“You have to remember that the general belief at the time was that all infectious diseases were a miasma—a kind of a cloud that could attach itself to things,” explained Vandervelde. “Therefore anything could be subject to infection.” Not everything was considered equally conducive to conveying miasma, however: Soft materials, such as cloth, wool, and even fruits and vegetables, were thought to be highly susceptible, whereas hard objects, such as wood, metal, and tortoiseshell, were seen as impervious to infection. Paper sat in between these two extremes—it was seen as theoretically susceptible, but not especially likely to carry disease.

“In the early days, the mail was simply put into a wooden coffin with sweet-smelling herbs and spices,” he said. “It had to be in there for at least a week, and, if it wasn’t collected in six weeks, it would be destroyed.” Later on, health commissioners in the Mediterranean adopted a process they called the spurgo, or “purge”—“a much more violent treatment with vinegar and smoke.” In all cases, the logic was that these strong odors were capable of displacing any disease-ridden bad air that might have impregnated the paper en route. Letters were sprinkled with or dipped in vinegar, which left distinctive splash marks; they were then put on a wire grate and grilled, or held over a fire with tongs, whose ghostly impressions remain visible as white lines on a browned envelope. Health officials in some locations were known for their particularly enthusiastic disinfection; correspondence that passed through Marseille frequently emerged unreadable.

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Brittle, stained, discolored, and typically adorned with an official cachet or wax seal, the letters reassured recipients of their mail’s safety—on the outside, at least. Indeed, many Italian health authorities drew attention to the limitations of their disinfection, with a stamp that read netta fuori e sporca dentro, or “Clean Outside and Dirty Inside.” “You may well ask what on earth you were supposed to do when you received a letter like that!” Vandervelde said with a laugh. “Open it?” He told the story of a much later outbreak, when a circus entertainer from India brought smallpox to Launceston, Tasmania, in 1904. In response, the Australian postal service disinfected the city’s mail for three months, marking thousands of letters as treated. “Ninety-nine percent of recipients put those letters straight in the fire,” said Vandervelde.

An image of a disinfected letter from 1916.
A 1916 envelope from an Austrian war camp was stamped with Desinfizirt, meaning “disinfected.” (Wikipedia)

Later, when we returned to his house to spend an afternoon marveling at the highlights of his collection, Vandervelde showed us one of the earliest known examples of internal disinfection. “It’s from Naples, where they were very fierce,” he said. “As far as I know, they were the first to slit.” The letter had been slit open at each corner with a chisel to allow the fumigant inside.

This practice of slashing mail with chisels and awls, which left many letters in shreds, was later made obsolete by a device called a “rastel” (from the Latin rastellus, or “rake”), which resembles the love child of a waffle iron and a medieval torture device. Letters were placed between hinged, spiked plates, and punctured pre-fumigation—the particular pattern of holes punched through the paper, such as the offset grid used in Hamburg, Germany, or the distinctive sunburst of Mahón, Minorca, can provide disinfected-mail collectors with yet another clue as to the date or location of a letter’s treatment.

The study of disinfected mail began in the 1950s. In San Francisco, a scientist named Karl F. Meyer came across an 1898 letter stamped MIT FORMALIN DESINFICIERT (“Disinfected With Formalin”). He was sufficiently intrigued to start a collection, and, in 1962, published Disinfected Mail, still the only comprehensive book on the subject.

When a young Vandervelde acquired his first disinfected letters, it was thus Meyer’s book to which he turned. The next time Meyer was in London, the two of them had dinner. They became fast friends, though Meyer died just before Vandervelde founded the Disinfected Mail Study Circle in 1973. “I’ve got a letter from him saying you’ll be lucky if you get more than six members,” said Vandervelde. “We’re now 150 strong, in 25 countries, and still growing.” He estimates that at least a third of DMSC members are medical historians or doctors, a third are collectors, and another third are stamp dealers or authors who write about related subjects. (We joined the circle in 2009.)

Until recently, the benefits of membership included a subscription to Pratique, the society’s newsletter. Each issue, although occasionally many months delayed because of technical difficulties involving Vandervelde’s antiquated AOL account, is filled with stories and scenes that convey the flawed reality of quarantine. At times, his research has revealed outbreaks that had otherwise been lost to history: an 1897 outbreak of plague in India that triggered disinfection measures in southern Russia and, for one day only, in New York City. (There, a paranoid postmaster decided, seemingly on his own initiative, to fumigate a bag of mail from India that had arrived on the steamship Britannic.)

If the letters themselves are pieces in a puzzle, Vandervelde and his colleagues are obsessive in their desire to fill in the gaps, collecting maps and tracking down contemporary sanitary proclamations that shed light on the slightest variation in quarantine practices. In painstaking detail, for missive after missive, Vandervelde has traced how, where, and why quarantine operated in the premodern world—a largely forgotten geography of lazarettos, rastel stations, merchant ships, colonial checkpoints, health passports, and border crossings.

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Bureaucratic processes are how a jurisdiction establishes itself: The issuing of coinage and postage stamps tends to be the first order of business for a new state. Similarly, the otherwise imaginary and invisible line around a country—its border—is typically articulated through quarantine and other health-screening practices: Disease management, by attempting to keep microbes out, defines the edges of in.

Thus, when the southern provinces of the Netherlands seceded, in 1830, to form their own country, Belgium, they issued their own coins and stamps in the subsequent decades. They also introduced quarantine controls, including the disinfection of mail. “Wanting to be quite different from both the Dutch and the French, they decided that the way they would deal with mail was to open up each letter, smoke it, and then reseal it by sticking a label with an apology in French,” Vandervelde said. This label—a 3-by-2-inch rectangle of heavy cartridge paper, in a distinctive shade of gray—is Vandervelde’s white whale. Because the label was typically stuck over the fold, it was almost always ripped in half to get at the letter inside. “Consequently, there are only, as far as I know, three examples in the world of this thing complete, and two of them are almost certainly printers’ samples,” he said.

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In addition to its rarity, one of the things that makes this Belgian disinfection label particularly significant is that 1830 also marks the first outbreak of cholera in Europe. The disease seems to have been endemic in the Ganges Delta region for centuries, but just four years earlier most Europeans had likely never heard of it.

By 1831, cholera had reached Finland, Poland, and Austria. From there it spread to the Baltic ports, arriving in Sunderland, England, by December 1831, in New York City and Philadelphia a year later, and in Mexico and Cuba soon after that. In Russia alone, more than a quarter of a million people died of cholera. Over the next 60 years, four more deadly cholera pandemics would sweep across Europe and the world, killing more people more quickly than any other epidemic disease of the 19th century. Meanwhile, European and American attempts to prevent its spread ended up defining the systems of global governance that still shape the world today.

Alison Bashford, an Australian historian, explained to us that Europe’s fear of cholera became focused, in particular, on a suspected super-spreading event—the hajj. Since medieval times, hundreds of thousands of Muslims from the Middle East and Asia had undertaken this sacred pilgrimage to Mecca every year, but their journeys—by camel caravan and by sail—took so long that any disease they might have been carrying would have revealed itself, and then burned out, en route.

By the mid-1800s, the accelerated pace of travel by railway and steamship risked seeding new outbreaks on Europe’s borders. In response, Western authorities attempted to control the spread of cholera—and the movement of Muslims—by setting up quarantine camps. One of these camps was located at El Tor, a tiny port at the tip of the Sinai Peninsula, where the Suez Canal opens onto the Red Sea. It was run by Egyptians under the direction of the European powers who had organized themselves into a sanitary and quarantine board with broad authority to ensure that ships arrived in Alexandria, on the Mediterranean end of the Suez Canal, free from disease.

According to Vandervelde, who has a postcard mailed from this camp in his collection, conditions at El Tor “were primitive in the extreme.” He showed us illustrations from The Graphic magazine that depicted a handful of wooden sheds built on the beach to house passengers, the distinctly spartan interior of the “Ladies’ Quarantine Shed,” and the even more austere “Cholera Tent,” for those who fell sick. Of course, every time anyone did show symptoms, the quarantine’s duration was extended, meaning that pilgrims could easily spend months waiting on the beach, subjected to intense daytime heat and freezing cold nights, as well as a persistent north wind that blew sand into every crevice. (Conjunctivitis and other eye conditions were common.) Two cisterns were available for five hours a day, to serve 300 or more people, leading one pilgrim to report “nights spent tormented by thirst.”

In addition to being considered disease vectors by European authorities, the pilgrims were Muslim and thus perceived as threatening to colonial rule. Through quarantine, the edges of Europe were made visible—and could be medically enforced.

As the 19th century unfolded, quarantine began to fall out of favor. Critics claimed that it was arbitrary and, for the most part, useless, even while it also exacted an enormous economic cost in terms of lost time and trade.

Britain, which once conducted so little trade with the East that it hadn’t bothered to build a national quarantine station, now relied on the free flow of goods and people to maintain its global empire. At the same time, other countries did not share that view—or that economic model—and would happily subject British ships to retaliatory quarantine if they felt its sanitary precautions were not adequate.

In the 1850s and ’60s, British authorities devised a combination of measures, in lieu of quarantine, that came to be known as “the English preventive system.” This multifaceted approach involved epidemiological intelligence efforts, including tracking outbreaks overseas and monitoring the health of newly arrived travelers, along with investments in public sanitation. The system was designed to catch and isolate the sick, rather than simply detain everyone at the border for mandatory observation. It worked: No major cholera outbreaks occurred in England after 1866.

This neo-quarantine, pioneered by the British and eventually adopted by the rest of the world as the basis of global health, still operated by controlling mobility (of people and thus their germs). It simply replaced the physical barrier of lazarettos and cordons sanitaires with a selective, surveillance-based one—which relied on data rather than buildings. This shift, from fixing people in space with architecture to tracking their movements and contacts, required the development of novel techniques and bureaucracies with which to define and verify individual identities.

Today, we know these techniques and bureaucracies as the “passport” and “passport control,” but the earliest such documents were health passports. From the 1500s, local authorities would issue these formal printed documents, known in Italian as fedi di sanitá, to travelers hoping to avoid quarantine at their destination.

As “a bit of a breather” between showing us his collections of quarantine letters and disinfected mail, Vandervelde allowed us to inspect some of the earliest health passports in his collection. “The reason I’ve selected these is that, until about 1700, paper was very expensive, and therefore they use very small sheets,” he said. “As time went on and paper became cheaper, the passports got bigger and bigger and bigger and ended up enormous—so these obviously are easier to show.”

Like quarantine, after the 1950s, “disinfected mail more or less disappears,” Vandervelde told us. The most modern item in his collection dates to 1972, when, just as the World Health Organization was preparing to declare smallpox eradicated, a Yugoslav guest worker in Hanover, Germany, was taken to the hospital and quickly isolated, suffering with what local doctors described as “a fulminating pox.” He had been in Germany for only two weeks, but smallpox is highly contagious: Tracking down all his contacts was essential, as many of them might also be infected. There was just one problem. “He was a very handsome young man,” said Vandervelde, “and when they put his picture in the local newspaper and asked for anybody who’d seen this man to come forward, 283 girls claimed to have met him.”

The authorities dutifully rounded up all 283 young women, housing them in village halls and Scout huts for a period of quarantine. Smallpox, as it happens, is one of the very few pathogens whose transmission through the mail has actually occurred—Vandervelde told us that, during the American Civil War, there were six authenticated cases of wives or girlfriends who, on receipt of a letter from their smallpox-stricken beau at the front, “kissed it or put it into her bosom and later went down with smallpox.” With their old rastels and tongs consigned to the museum, German authorities decided to disinfect any letters sent from quarantine by the girls to their friends and families by wrapping the envelopes in muslin and ironing them three times at the highest setting.

Even more recently, following the 2001 anthrax attacks, the U.S. Postal Service determined that letters and parcels sent to zip codes beginning in 202, 203, 204, and 205, which serve federal-government agencies in Washington, D.C., should be treated. A company that irradiated food to extend its shelf life won the contract, and, although USPS has declined to comment, the agency’s website says that mail destined for those zip codes is still forwarded to New Jersey, where it is put on a conveyor belt and passed under a high-energy beam of ionizing radiation to kill bacteria and viruses. The letters and packages are then “aired out” for a while, before being forwarded to their destinations. The paper is left slightly faded and somewhat crispy, but sterile—and, at least sometimes, stamped as such. “Those cachets typically go for about $25,” Vandervelde said. “I think even that’s overpriced for something that recent.”

In the early days of the coronavirus pandemic, as public-health authorities resorted to the medieval technology of quarantine, they also wondered whether they ought to resurrect mail disinfection. Early studies indicated that the virus could survive for 24 hours on cardboard surfaces, perhaps longer on paper, although we now know that most infections are transmitted by aerosols. Nevertheless, in February 2020, China’s central bank began quarantining the country’s cash, collecting banknotes from Hubei, the worst-hit province, then baking them at a high temperature or bathing them in ultraviolet rays. The newly laundered cash was then kept in isolation for seven to 14 days before being rereleased. A few weeks later, the U.S. Federal Reserve began quarantining dollar bills repatriated from Asia, holding them for seven to 10 days before allowing them to reenter the domestic financial system.

As the pandemic dragged on, pushback began against the introduction of health-based QR codes as a means of restricting individual movement, as well as the promise, or threat, of international vaccine passports. Such anxieties do, in fact, have historical justification: As our tour of disinfected mail with Denis Vandervelde had shown, the temporary infrastructure and controls on mobility put in place during an outbreak can harden into permanent borders, bureaucracy, and, too often, inequities. The world around us is structured by the ghosts of quarantines past.

This post was excerpted from Until Proven Safe: The History and Future of Quarantine.