Perri Klass in Smithsonian:
Even Noah Webster, that master of words, did not have a name for the terrible sickness. “In May 1735,” he wrote in A Brief History of Epidemic and Pestilential Diseases, “in a wet cold season, appeared at Kingston, an inland town in New-Hampshire, situated in a low plain, a disease among children, commonly called the ‘throat distemper,’ of a most malignant kind, and by far the most fatal ever known in this country.” Webster noted the symptoms, including general weakness and a swollen neck. The disease moved through the colonies, he wrote, “and gradually travelled southward, almost stripping the country of children….It was literally the plague among children. Many families lost three and four children—many lost all.” And children who survived generally went on to die young, he wrote from his vantage point of more than half a century later. The “throat distemper” had somehow weakened their bodies.
In 1821, a French physician, Pierre Bretonneau, gave the disease a name: diphtérite. He based it on the Greek word diphthera, for leather—a reference to the affliction’s signature physical feature, a thick, leathery buildup of dead tissue in a patient’s throat, which makes breathing and swallowing difficult, or impossible. And children, with their relatively small airways, were particularly vulnerable.
…Then, toward the end of the 19th century, scientists started identifying the bacteria that caused this human misery—giving the pathogen a name and delineating its poisonous weapon. It was diphtheria that led researchers around the world to unite in an unprecedented effort, using laboratory investigations to come up with new treatments for struggling, suffocating victims. And it was diphtheria that prompted doctors and public health officials to coordinate their efforts in cities worldwide, taking much of the terror out of a deadly disease.