Titans of History

PASTEUR

1822–1895

There are not two sciences: there is science and the application of science; these two are linked as the fruit is to the tree.

Louis Pasteur

The French microbiologist Louis Pasteur was a scientist whose varied and innovative studies made a massive contribution to the battle against disease in humans and animals. He did much pioneering work in the field of immunology, most importantly producing the first vaccine against rabies. His investigations into the micro-organisms that cause food to go bad were of vital importance to French and British industry, while the process of pasteurization he developed is still extremely important in preserving food and preventing illness.

Pasteur came from a family of tanners. As a child he was a keen artist, but it was clear to his teachers that he was academically very able. In 1843 he was admitted to the fine Parisian training college the École Normale Supérieure. He became a master of science in 1845, and in 1847 he presented a thesis on crystallography which earned him a doctorate.

With such a prestigious academic background and some ground-breaking research into physical chemistry behind him, Pasteur gained a professorship in the science faculty at the University of Strasbourg. Here he met Marie Laurent, the daughter of the university rector; they were married in 1849 and had five children together, two of whom survived childhood.

After six years in Strasbourg, Pasteur moved on to Lille. He held the firm view that the theoretical and practical aspects of science should work hand in hand, so he began teaching evening classes to young working men in Lille and taking his regular students around nearby factories. He also began to study the process of fermentation; one of his early achievements, in 1857, was to show that yeast could reproduce in the absence of oxygen. This became known as the Pasteur effect.

By 1857 Pasteur was back at the École Normale Supérieure. Here he continued his research into fermentation and demonstrated with unusual experimental rigor that the process was driven by the activity of minute organisms. In 1867 the French emperor Napoleon III relieved Pasteur of his teaching duties and granted him a research laboratory. With a new freedom of study, Pasteur set about resolving, once and for all, the great scientific debate over spontaneous generation—the question of whether germs and micro-organisms could simply “appear” from nowhere. He found that germs were in fact transported in air and that food decomposed because it was exposed to them.

In 1862 Pasteur first tested the process, now known as pasteurization, by which milk and other liquids are heated to remove bacteria. In time this process would revolutionize the way food was prepared, stored and sold, and so save many people from infection. Pasteur also applied his theoretical work to the French vinegar and wine industries and the British beer industry, allowing the businesses concerned to produce goods that did not perish so quickly. It was as a result of a suggestion from Pasteur that the British surgeon Joseph Lister began in the 1860s to adopt antiseptic methods during operations.

In 1865 Pasteur saved the French silk industry by helping to identify and eradicate a parasite that was killing silkworms. By 1881 he had developed techniques to protect sheep from anthrax and chickens from cholera. He observed that creating a weakened form of a germ and vaccinating animals with it gave them effective immunity. It was an important development of Jenner’s earlier use of cowpox germs to vaccinate against smallpox.

The most important vaccination Pasteur produced was against rabies. By manipulating the dried nervous systems of rabid rabbits, he created a weakened form of the terrible disease and managed to inoculate dogs against it. He had treated only eleven dogs in 1885 when he took dramatic action to save the life of a nine-year-old boy who had been bitten by a rabid dog. It was extremely risky but totally successful. Pasteur remained a hero of the medical establishment until his death, after a series of strokes, in 1895. He was buried in Notre Dame Cathedral in Paris, then reinterred in a crypt at the Pasteur Institute.

Pasteur was one of many scientists who have performed medical miracles that have done so much to alleviate human suffering. Edward Jenner was one of the first, immunizing a child against smallpox in 1796. From the 1860s Joseph Lister (1827–1912) began his pioneering work on asepsis in surgery, using carbolic acid as an antiseptic to reduce the risk of infection. Operations had already been rendered far safer in the preceding decades by the physician John Snow (1813–58), who had introduced the use of anesthesia to enable pain-free operations. Snow was also responsible for reducing the incidence of cholera by tracing its cause to contaminated water supplies.

In 1895 the German physicist Wilhelm Röntgen (1845–1923) discovered X-rays, thereby paving the way for vast improvements in the treatment of internal injuries. In 1928 Alexander Fleming (1881–1955) discovered penicillin, the first antibiotic, when he noticed that the mold in a dirty lab dish prevented bacteria from growing. In the 1950s the work of the French immunologist Jean Dausset (b. 1916) led to great advances in our understanding of how the body fights disease. In 1953, Francis Crick (1916–2004) and James Watson (b. 1928) discovered the double-helix shape of DNA. All those who worked on these projects deserve to be remembered as heroes of medicine.