Reporting from Jacksonville, Fla., during an 1888 outbreak of yellow fever, a correspondent for the Macon Telegraph wrote, “Well, another day has dawned and is half gone (I write at noon), and still we live.”

Not all Jacksonville residents were quite so upbeat. Yellow flags marked homes that hosted infection. Thick plumes of smoke from coal fires hung in the air and the local artillery battery fired off rounds throughout the evening — both efforts to obliterate the microbes believed to be hanging in the night sky. Between late July and early December of that year, Jacksonville faced approximately 430 deaths and more than 4,600 cases of yellow fever.

With half of the towns in Florida under quarantine, many local businesses called for a return to normalcy. The Florida Times-Union published a fiery op-ed bashing the postal system for delaying deliveries due to one key practice: the disinfection of mail.

During the current covid-19 pandemic, the Centers for Disease Control and Prevention and the World Health Organization continue to indicate there is no evidence that the virus spreads through the mail. But as seen during past outbreaks, fears of contamination have had a major impact on the postal industry.

The practice of disinfecting mail — whether it was exposing letters to burnt perfume, tobacco or cyanide gas — originated hundreds of years before the birth of the United States. The most common method of disinfection during the colonial period was soaking letters in vinegar. Eventually, the practice of puncturing letters believed to carry infection and steaming them with sulfur became the preferred tactic.

In a 1797 letter from Baltimore describing the city’s yellow fever outbreak, the author accused the city’s health commissioner of suppressing knowledge that the illness had reached the city. This particular piece of mail is notable due to its discolored appearance and sizable slice, indicating that the letter had been fumigated with sulfuric acid prior to delivery. This was the same practice that delayed Florida’s mail during the 1888 outbreak that drew the ire of the Florida Times-Union.

In response to fears that yellow fever might spread from Florida to the rest of the country, one of the largest mail-fumigation operations was established just outside Waycross, Ga. A vital railway hub connecting Florida to neighboring states, Waycross became the home of “Camp Detention.” There, passengers wishing to escape Florida were held for observation and all mail leaving Florida was fumigated. The site soon earned the name “Camp Destitution” from a detainee who had grown tired of his time trapped in Southern Georgia amid the smell of pine and brimstone.

Outfitted with shelves of chicken wire and large kettles, multiple boxcars were filled with punctured mail and steamed with sulfur gas. This practice delayed mail delivery by several days, as each carload of letters was to be steamed for at least six hours.

Camp Destitution operated from August until mid-December, but that was not Waycross’s last experience with mail disinfection. The city also served as a fumigation center during a yellow fever outbreak in 1893. When rumors began circulating of the illness spreading to Waycross, local councilmen passed an ordinance to penalize those who “circulate any false report against the health of the city.”

The 1890s would also bring a cholera scare in the northern United States that originated in Europe. U.S. postmasters across the Canadian frontier were instructed by the Postal Department to confer with their local health officials to determine what, if any, precautionary measures would be necessary to disinfect mail.

Responses were mixed. Detroit’s postmaster decided sterilization was unnecessary, while Chicago’s postmaster encouraged fumigation using sulfur. Buffalo health commissioner Ernest Wende was trained in germ theory and credited with advancing the health practices of one of the country’s fastest-growing centers of commerce. Wende advised the city’s postmaster to perforate letters and subject them to “dry heat” for extended periods of time to eradicate any disease.

Accounts of mail disinfection in the United States lessened around the early 1900s as medical professionals and officials began to accept that letters did not serve to carry disease. The last few holdouts for this practice were several leprosy camps, such as Hawaii’s Kalaupapa leprosy settlement, which discontinued fumigating mail in the late 1960s.

Fear of the intentional transmission of anthrax through the mail in 2001 led the U.S. Post Office to experiment with an electron beam irradiation system to kill the bacteria. Despite advances in science, this was nothing new. Researchers had been trying to eradicate anthrax from letters more than 200 years earlier. In 1885, scientists with the Public Health Service conducted experiments to prevent the spread of anthrax through the mail, but other, more widespread diseases garnered the most attention.

Although it is now widely accepted that mail does not serve as a means of transmitting major viruses, experts recognize the significance of early postal officials to ensure public health.

“Much of the effort expended to disinfect mail over a period of 500 years might first appear to have been futile in light of modern knowledge. But even in its futility, the heroic effort at disinfection of mail created an awareness of contagion and a favorable attitude toward isolation and quarantine in this country,” wrote Emmet Pearson and Wyndham Miles for the Bulletin of the History of Medicine in 1980. “Although some early disinfection methods were not scientifically conceived, they did help to eliminate rats, lice, fleas, and mosquitos, and, by acts of serendipity, were partly successful in disease control.”

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