Louis Pasteur by Nicola Kingsley - National STEM Centre

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Pasteur experimenting on a chloroformed 36 rabbit They found that if the saliva was injected into rabbits, the rabbits developed rabies. There was still a problem: they were unable to find the microbe responsible, although Pasteur was sure it must be there. The microbe is a virus, too small to be seen through any microscope available in Pasteur's time. A further problem was that the incubation period for rabies-the time it took for symptoms to appear-was quite lengthy. A person bitten by a rabid animal would take at least two weeks to show signs of the disease. Having to wait a long. time for signs of infection slowed the experiments down. Pasteur thought that as the symptoms included madness and convulsions, the brain and nervous system might be affected. Perhaps it would be better to introduce infected tissue directly into the nervous system. To do this he drilled a hole in the skull of the rabbit which he wanted to infect with rabies. The method proved successful; the incubation period became both shorter and more certain. Having decided that the microbe was in nervous tissue, he set about finding a method of weakening it. The most successful approach proved to be by drying out of lengths
of spinal column taken from rabbits with rabies. After fourteen days of exposure to air the microbe seemed to be no longer virulent. By giving an injection of spinal column dried for fourteen days, followed the next day by some dried for thirteen, the following day by some dried for twelve, and so on, he could produce complete immunity in two weeks. A final injection of virulent material would fail to produce the disease. Actually, drying the spinal column did not weaken the virus, it just decreased the number of virus particles-but being unable to see the virus, Pasteur could not know that. His model of vaccination involved using weakened microbes, and that was what he thought he was doing. Pasteur tried the course of vaccination on fifty dogs, with complete success. He did not like to see suffering and always tried to make sure that the animals used in his experiments experienced as little pain as possible. Nonetheless his work brought him into conflict with anti-vivisectionists, people who believed that he was being cruel to animals and had no right to experiment on them. Having succeeded in vaccinating the dogs, Pasteur of course wanted to know if it would work with people. At first he did not dare to find out. It would be terrible if the vaccine failed, and someone died of rabies given to them during the experiment. It would amount to murder-and Pasteur's reputation would be ruined. He was, by now, a famous man, and many people took an ·interest in what he was doing. He lived ata time when railways were built allover Europe. Suddenly travel had become easier and faster, not only for people but also for letters, newspapers, books. At the same time, high-speed printing was being perfected. News and new ideas were travelling much faster than ever before in history. The news that Pasteur was working on rabies had reached the remote French region of Alsace, and when, in July 1885,a nine-year-old boy called Joseph Meister was bitten fourteen times by a mad dog, his mother rushed with him to Paris as fast as she could. She brought Joseph to Pasteur, and begged the scientist to help her son. 37
Page 2 and 3: Louis Pasteur by Nicola Kingsley Se
Page 4 and 5: • Louis Pasteur
Page 6 and 7: Pasteur's house 6 at Dole Pasteur g
Page 8 and 9: Pasteur dictating notes on silkworm
Page 10 and 11: Budding in yeast cells 10 bad vineg
Page 12 and 13: Pasteur in his laboratory 12 Pasteu
Page 14 and 15: A drop of pond water magnified to s
Page 16 and 17: 16 By 1859 no one had come any clos
Page 18 and 19: Mer de Glace on Mont Blanc where Pa
Page 20 and 21: 20 I ChaQter 4 A theory of disease
Page 22 and 23: The microscope used by Pasteur at W
Page 24 and 25: Lister greets Pasteur at the Sorbon
Page 26 and 27: 26 I Cha~ter 5 Farmyard microbes Wi
Page 28 and 29: Early vaccination for diphtheria 28
Page 30 and 31: Anthrax bacilli 30 with the disease
Page 32 and 33: A sheep being vaccinated 32 When he
Page 34 and 35: 34 His assistants brought the news
Page 38 and 39: Statue at the Pasteur Institute of
Page 40 and 41: The Pasteur Institute 40 The news o
Page 42: 42 Before his success with rabies,

Louis Pasteur by Nicola Kingsley - National STEM Centre

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