Louis Pasteur was born in 1822 in Dole, France. Louis Pasteur’s name is forever cemented in the history of medicine. He, along with Alexander Fleming, Edward Jenner, Robert Koch and Joseph Lister, is of great importance when studying medical history. Pasteur’s discovery – that of germs – may seem reasonably tame by the standards of 2002, but his discovery was to transform medicine and see his name forever immortalised on a day-to-day basis in pasteurised milk – named in his honour.


Pasteur is important for three reasons:

Pasteur showed that airborne microbes were the cause of disease. Pasteur built on the work of Edward Jenner and helped to develop more vaccines Pasteur’s career showed how conservative the medical establishment was at the time.

As a young man, Pasteur studied at the Ecôle Normale in Paris. In 1843, he became a research chemist. He developed such a reputation, that in 1854, aged just 32, he became Dean of the Faculty of Science at the University of Lille. At this time, Lille was the centre of alcohol manufacture in France. IN 1856, Pasteur received a visit from a man called Bigo who worked at a factory that made alcohol from sugar beet. Bigo’s problem was that many of his vats of fermented beer were turning sour and, as a result, the beer had gone off and had to be thrown away. From a business point of view, this was a disaster. Bigo asked Pasteur to find out why this was happening.

After using a microscope to analyse samples from the vats, Pasteur found thousands of tiny micro-organisms. He became convinced that they were responsible for the beer going sour. Pasteur believed that they caused the putrefaction of the beer – not that they were the result of the putrefaction.

Pasteur continued his work on this theme by studying other liquids such as milk, wine and vinegar. In 1857, he was appointed Director of Scientific Studies at the Ecôle Normale in Paris. Between 1857 and 1859, Pasteur became convinced that the liquids he had studied were being contaminated with microbes that floated in the air. The medical establishment ridiculed him:

“I am afraid that the experiments you quote, M. Pasteur, will turn against you. The world into which you wish to take us is really too fantastic.” La Presse, 1860

Pasteur was vilified in public but rather than give up, he determined to fight for what he believed in. Pasteur started to devise tests to prove that he was right. He was able to prove that:

Air contained living organisms That these microbes can produce putrefaction That these microbes could be killed by the heating of the liquid they were in That these microbes were not uniformly distributed in the air.

In April 1864, Pasteur explained his beliefs in front of a gathering of famous scientists at the University of Paris. He proved his case beyond doubt – even if some of those present refused to believe him including Dr. Charlton Bastian who maintained his belief that putrefaction came from within and not from invading micro-organisms.

Up to 1865, Pasteur’s work only involved beer, wine and milk. In 1865, he was asked to investigate his first disease called pébrine that affected the silk worm industry. Within a year, Pasteur had established that the disease was caused by a living organism and he now became convinced that microbes could also affect humans as well as beer and silk worms. In this sense, Pasteur believed that microbes could spread diseases among humans. Three of Pasteur’s daughters had died between 1859 and 1865; two from typhoid and one from a brain tumour.

In 1865, a cholera epidemic hit Marseilles. Pasteur carried out a number of experiments in a hospital in the hope of finding the germ that caused this feared disease. He was not successful.

In 1868, Pasteur suffered from a brain haemorrhage that affected the left side of his body. This affected his ability to work but the work that he had done up to 1868, had inspired a number of younger scientists.

Pasteur developed his work by finding out ways humans could be prevented from getting a disease. He was inspired by his own desire to develop his knowledge but also by patriotism. Robert Koch was getting a great deal of attention throughout Europe for his discoveries and the French versus German rivalry that occurred provided a great spur to medical advances. In 1881, Pasteur met Koch at a meeting in London when the German was giving a lecture on what he had discovered up to that date. All Pasteur said to Koch after the lecture was “That is great progress”.

Koch had gathered around him a team of skilled research scientists. Pasteur frequently worked by himself. He realised that this was not the way to proceed and he also gathered around him a team of research scientists. Pasteur had always lacked detailed medical knowledge. Because of this he introduced into his team two brilliant young doctors, Emile Roux and Charles Chamberland. The first disease this team worked on was chicken cholera – a disease that affected many poultry farmers.

Pasteur knew about the work done by Edward Jenner regarding smallpox. Pasteur reasoned that if a vaccine could be found for smallpox, then a vaccine could be found for all diseases. Pasteur did not know how Jenner’s vaccination worked so he had to proceed searching for a chicken cholera vaccine using a process of trial and error.

In the summer of 1880, he found a vaccine by chance. Chamberland had inoculated some chickens with chicken cholera germs from an old culture that had been around for some time. The chickens did not die. Pasteur asked Chamberland to repeat what he had done but with a fresh culture of chicken cholera germs. Pasteur reasoned that a new culture would provide more potent germs.

Two groups of chickens were inoculated; one that had been given the old culture and one group that had not. Those chickens that had been given the old culture survived, those that had not died. The chickens that had been inoculated with the old culture had become immune to chicken cholera. Pasteur believed that their bodies had used the weaker strain of germ to form a defence against the more powerful germs in the fresher culture.

In April 1881, Pasteur announced that his team had found a way to weaken anthrax germs and so could produce a vaccine against it. Despite his fame, there were still those in the medical world who mocked Pasteur.

“Will you have some microbe? There is some everywhere. Microbiolatry is the fashion, it reigns undisputed; it is a doctrine which must not even be discussed, especially when its Pontiff, the learned Monsieur Pasteur, has pronounced the sacramental words, “I have spoken”. The microbe alone is and shall be the characteristic of a disease; that is understood and settled;…..the Microbe alone is true, and Pasteur is its prophet.” Rossignol, written in 1881.

Rossignol was the editor of “The Veterinary Press” and in 1882 he challenged Pasteur to a public test of his anthrax vaccine. The tests were held in May 1882. Sixty sheep used in the test. Pasteur kept ten as they were and divided the other fifty into two groups of twenty-five. One group was inoculated with his vaccine while twenty-five were not. All fifty were then injected with the anthrax virus. Those that were not inoculated died within two days. The inoculated group suffered no ill-effects and were described as being “sound, and (they) frolicked and gave signs of perfect health”. They proved that Pasteur was not exaggerating the powers of his vaccine. “The Times” in Great Britain called Pasteur “one of the scientific glories of France”.

Pasteur and his team turned next to the disease of rabies. Most human victims of rabies died a painful death and the disease appeared to be getting more and more common in France. Though the team could not identify the germ, they did find that the rabies germ attacked the nervous system only after it had made its way to the brain. The team traced the germ to the brain and spinal cord of infected animals and by using dried spinal cords, they produced a vaccine for rabies. The vaccine was first tried out on animals.

Pasteur injected ‘clean’ animals with the rabies germ found in spinal cord that was fourteen days old. At this age, the germ was relatively weak and unlikely to threaten the life of the animals. He then used spinal cords that were thirteen days old, twelve days etc. on the animals until they were injected with the most virulent germ found in infected spinal cord that was fresh. All survived this. But Pasteur faced a serious problem. What worked on animals might not work on humans.

In 1885, a young boy, Joseph Meister, had been bitten by a rabid dog, and was brought to Pasteur. The boy almost certainly would have died an agonising death if nothing was done so Pasteur took the risk on using his untested vaccine.

“The death of this child appearing to be inevitable, I decided, not without lively and sore anxiety, as may well be believed, to try upon Joseph Meister, the method which I had found constantly successful with dogs. Consequently, sixty hours after the bites, and in the presence of Drs Vulpian and Grancher, young Meister was inoculated under a fold of skin with half a syringeful of the spinal cord of a rabbit, which had died of rabies. It had been preserved (for) fifteen days in a flask of dry air. In the following days, fresh inoculations were made. I thus made thirteen inoculations. On the last days, I inoculated Joseph Meister with the most virulent virus of rabies.” Pastuer

The boy survived and Pasteur knew that he had found a vaccine for rabies. Three months later, when he examined Meister again, Pasteur reported that the boy was in good health.

Ironically, though Pasteur and his team knew that the vaccine worked, no one then in the world of science knew how it worked!