French chemist Louis Pasteur (1822-1895) was one of the truly brilliant minds of the nineteenth century, whose groundbreaking work in the field of microbiology and chemistry led to a long list of scientific discoveries. He is perhaps best remembered today for his development of "pasteurization" in milk, and the invention of a number of vaccines, including rabies, and anthrax. His discovery of a vaccination for cholera, however, was something of an accident, although he was aware of the work of Edward Jenner (1749-1823), who pioneered the smallpox vaccine.
In the summer of 1880, Pasteur was conducting experiments on chickens with cholera, and had instructed his assistant Charles Chamberland to inoculate the birds with a culture of cholera-bacteria. Chamberland failed to do so, and a month later the culture, which had now spoiled, was used of the birds. They became ill but did not die, so Pasteur introduced a new group of chickens and inoculated them all with a fresh culture of the bacteria. Those that had received the old culture survived, but the new group of chickens all died, which led Pasteur, like Jenner before him, to realize that the weakened bacteria produced immunity in the subject. The difference between Jenner and Pasteur's work, however, was that Pasteur was using an artificially generated form of the bacteria. This allowed the vaccine to be created in large quantities and revolutionized the prevention of disease. Following his successes with cholera, Pasteur went on to create the vaccination for anthrax (1881) and then rabies (1895).
Despite Pasteur's successes and fame, there were still sceptics within the medical world during his day who failed to appreciate his advancements in the treatment of infectious diseases.