After the smallpox vaccine of 1799, little happened in infectious disease for fifty years. Physicians decided that disease was part of life, it existed within us and could not be eradicated, leading to a philosophy of “therapeutic nihilism.” Doctors could follow the course of tuberculosis with stethoscopes as it ate through a lung, but did not hope to stop the process.
Nursing and nutrition improved during the 1850s and 1860s (think Florence Nightingale).Sanitation would soon have a beneficial effect on health, but the idea that disease came from infection by bacteria, viruses, or fungi, occurred to no one. Until Louis Pasteur discovered that yeast and bacteria act on beef broth, grape mash, andflour to alter them—in beef broth by putrefaction and degradation of proteins, in grape mash by converting sugar to alcohol and inbread by making carbon dioxide causing bread to rise, puffed up by the CO2.
Louis Pasteur was from Artois in the Jura mountains where the wine was awful.He looked at it with a microscope, expecting to find yeast—recognizable spheres with buds, but found yeast and contaminating bacteria. He told the vintners to start again with pure yeast and to clean all their equipment with heat. The wine improved. (Pasteurization was first used to preserve wine, not milk.)The eventual result was the Germ Theory of Fermentation, Putrefaction, and Disease. Pasteur became famous and repeated his success with diseases of silk moths and sour beer. It was a fertile theory and remains so.
Chemists of the mid-19th century hated the germ theory. They could not bear to see their tidy chemical equations corrupted by bacteria or yeast. They thought it was a form of mystical vitalism, but had no alternative theory to explain how sugar turns into other molecules. They conceded, but it took decades.
Physicians could not believe that anything as small as bacteria could fell a human being and many of them believed in spontaneous generation of bacteria from inert chemicals, an idea that Pasteur destroyed. Physicians thought he was an unqualified upstart, a charlatan poaching on their territory. Pasteur, a fine speaker and something of a showman, returned their contempt.
In the 1870s, French cattle were suffering from lethal anthrax infections; farmers lost 15% of their herds.
What of the long gap between vaccines?From about 1850, Pasteur and his students and Joseph Lister in Scotland, worked out ways to grow and examine bacteria and yeast in beef broth or other nutrient liquids.They disproved spontaneous generation andlearned that microorganisms could grow without oxygen, that anthrax bacteria could make heat resistant spores, and that bacteria could be kept out of wounds, reducing infection.
In the 1870s, French cattle were suffering from lethal anthrax infections; farmers lost 15% of their herds. The Minister of Agriculture asked Pasteur for help, and he sent two assistants to a farm near Chartres where cattle, sheep and pigs were dying. The assistants reported to Pasteur, who asked about birds.Ducks, chickens, and geese were thriving.
How to account for this? Pasteur knew that birds have an internal temperature of 42 degrees C, while mammals live at 37 degrees C.The difference is 9 degrees Fahrenheit, which is a lot. He asked if the small opaque bodies, called batonettes, found in the blood of cattle or sheep dying of anthrax were bacteria that would grow in beef broth. They did. He then injected a hen with batonettes. Nothing happened. When he cooled the hen in a bath it sickened. Removed from the bath the hen recovered.
He reasoned that if he grew the bacteria at 42 degree C in beef broth they might lose the ability to kill at 37 degrees C.They did. The bacteria, Bacillus anthracis, were attenuated, they had lost some function (a piece of DNA as it turned out) but still grew. These bacteria formed the basis for a sheep and cattle vaccine. These bacteria were called the Pasteur vaccine strain and was used for many years. (My lab worked with it until we learned, just after 9/11, when there was anthrax terrorist attack, that the FBI and CDC test for anthrax did not recognize the vaccine strain as harmless. Not wanting to scare people, we killed our cultures with superheated steam.)
A trial took place in a village called Pouilly-le-fort, Southeast of Paris. Twenty-five sheep were inoculated with attenuated Bacillus anthracis and 25 were left alone. Two weeks later the 25 inoculated sheep were given a booster. After another two weeks all 50 sheep got a dose of virulent bacteria. In two days, the unvaccinated sheep were very sick, the vaccinated sheep were healthy. In later tests, the same held true for cattle. Pasteur, who knew what was at stake for farmers, agriculture, and medicine, paced in his lab at The École Normale Supérieur in Paris. Finally, a telegram arrived. It read Succès Épatant! (Stunning Success).
Richard Kessin, PhDis Professor Emeritus of Pathology and Cell Biology at The Columbia University Irvine Medical Center.
