Diphtheria antitoxin

In December 1890 Emil von Behring and Shibasaburo Kitasato, working at Robert Koch's Institute for Infectious Diseases in Berlin, published results showing that animals could be made resistant to diphtheria and tetanus by tiny doses of the germ's poison. They also showed that serum, the clear part of the blood, from such animals could protect or cure other animals. Behring called the active substance antitoxin. It was first used on a sick child in Berlin at Christmas 1891.¹

Louis Pasteur and Koch had established that microbes cause disease. Friedrich Loeffler identified the diphtheria bacillus in 1884, and Emile Roux and Alexandre Yersin showed in 1888 that it does harm through a toxin it releases, which causes the choking membrane in the throat and damage to the heart. Edward Jenner's vaccination of 1796 had shown immunity can be induced. Behring and Kitasato built on all of these. Paul Ehrlich then worked out a reliable method to measure doses in 1894, making antitoxin a dependable drug, produced in horses.¹

Diphtheria was a leading killer of children, and serum cut death rates sharply. Behring received the first Nobel Prize in Physiology or Medicine in 1901. Kitasato was left out, a decision many have regarded as unfair. The antitoxin was later joined by diphtheria toxoid vaccines in the 1920s, and its fame peaked in 1925 when relays of dog sleds carried serum to Nome, Alaska, during an outbreak.¹³