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Discovery of the Rabies Virus

Rabies is a viral disease of the nervous system that causes over 55,000 deaths in the world each year, according to the Centers for Disease Control and Prevention. Most of these deaths are in the underdeveloped world. Dr. Louis Pasteur first discovered the cause of rabies--a virus in the saliva and nervous tissue of rabid animals. He did so in the late 1800s by experimenting with rabid mammals like rabbits and dogs. In 1885, he developed the first successful rabies vaccine. The virus was not seen through a microscope until the 1950s.

  1. Louis Pasteur

    • Dr. Louis Pasteur was a French scientist who made contributions to the field of microbiology in the 1800s. His main line of work was in determining the causes of different diseases. Unlike many of his colleagues, Pasteur did not believe that diseases came out of nowhere.

    Germ Theory

    • At the time of Pasteur's work, the common belief was that germs came about spontaneously, out of nowhere. Pasteur proved, through a series of experiments, that germs had to be seeded before they could grow and reproduce. Through his work, he was able to confirm the causes of different diseases and how to prevent them. It is because of him that milk is said to be "pasteurized" when it is heated and cooled to get rid of microbes in it.

    Koch's Postulates

    • A contemporary of Pasteur, Dr. Robert Koch, developed a series of tests to determine if a microbe was the cause of a disease. Scientists call these "Koch's Postulates," and they are still in use today, though slightly modified. The postulates stated that a germ that causes disease in one organism must cause the same disease in another organism before the germ can be named as the cause. As Pasteur transferred brain tissue from one rabbit to another, each subsequent rabbit would contract rabies. Although the virus could not be seen through microscopes of the time, Pasteur proved that "something" in the brain and saliva of a rabid animal was giving rabies to the healthy animals exposed to the brain and saliva. It would not be until the development of electron scanning microscopes in the 1950s that the virus actually would be seen.

    Rabies Virology

    • The rabies virus is an RNA virus that infects nerve cells of mammals. When a healthy mammal comes into contact with saliva or other body fluids from a rabid mammal, the virus travels through the nerves into the brain. Once in the brain, the virus continues to multiply and cause destruction of nerve cells there. While it is not a problem in the developed world, rabies kills over 55,000 people each year in underdeveloped nations, according to the Centers for Disease Control and Prevention.

    Rabies Vaccine

    • As Pasteur passed the rabies virus from one rabbit to another, he noticed that the next rabbit was not as sick as the previous rabbit. He also noticed that a point came where the rabbits were not acquiring rabies at all. Like Edward Jenner a century before, Pasteur theorized that the germ causing rabies was weakening, and exposure to a weakened virus gave immunity to the exposed animal. After experimenting with dried rabbit brain given to dogs to immunize them, Pasteur experimented on a young boy in 1885. The boy had been bitten by a rabid dog. Because rabies did not develop in the boy, Pasteur earned a place in history by developing the rabies vaccine. Today, the vaccine must be given as soon as possible after exposure to a rabid animal for it to be effective.

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