Pasteur determined the natural history of anthrax, a fatal disease of cattle. He proved that anthrax is caused by a particular bacillus and suggested that animals could be given anthrax in a mild form by vaccinating them with attenuated (weakened) bacilli, thus providing immunity from potentially fatal attacks. In order to prove his theory, Pasteur began by inoculating 25 sheep; a few days later he inoculated these and 25 more sheep with an especially strong inoculants, and he left 10 sheep untreated.
He predicted that the second 25 sheep would all perish and concluded the experiment dramatically by showing, to a skeptical crowd, the carcasses of the 25 sheep lying side by side. 15(p288) Pasteur spent the rest of his life working on the causes of various diseases—including septicemia, cholera, diphtheria, fowl cholera, tuberculosis, and smallpox—and their prevention by means of vaccination. He is best known for his investigations concerning the prevention of rabies, otherwise known in humans as hydrophobia.
After experimenting with the saliva of animals suffering from this disease, Pasteur concluded that the disease rests in the nerve centers of the body; when an extract from the spinal column of a rabid dog was injected into the bodies of healthy animals, symptoms of rabies were produced. By studying the tissues of infected animals, particularly rabbits, Pasteur was able to develop an attenuated form of the virus that could be used for inoculation. 15(p294)
Pasteur’s research on rabies resulted, in 1888, in the founding of a special institute in Paris for the treatment of the disease. This became known as the Institut Pasteur, and Pasteur himself directed it until he died. (The institute still flourishes and is one of the most important centers in the world for the study of infectious diseases and other subjects related to microorganisms, including molecular genetics. ) By the time of his death in Saint-Cloud on September 28, 1895, Pasteur had long since become a national hero and had been honored in many ways.
He was given a state funeral at the Cathedral of Notre Dame, and his body was placed in a permanent crypt in his institute. 1) Antitoxin and Breakthroughs in Plague Understanding Antitoxin, antibody produced in the bloodstream of an animal or human being in response to the presence of a bacterial toxin, or poison. The antitoxin neutralizes the effect of the toxin. In 1890, the German physician Emil Adolph von Behring was the first to demonstrate that animals immune to diphtheria have substances in their blood serum that neutralize the toxin produced by the diphtheria bacterium.
Serum antitoxins were first prepared and used in the treatment of diphtheria by the French bacteriologist Pierre Paul Emile Roux in 1894. Today, similar antitoxins are used to combat the toxins produced by tetanus and botulism. Antitoxins for use in human beings are produced in animals such as horses and cattle. The animal is injected with increasingly higher doses of the toxin and its defense processes respond by producing antitoxin. Some of the animal’s blood is then removed and processed for use in human beings.
An animal may be used to produce antitoxin for many years without apparent damage to itself. Egon Weck have found that while the use of antitoxins and antibiotic drugs that are available in the rare instances when diphtheria infections occur, death still claims 5 to 10 percent of diphtheria victims stressing the need for immunologists and pediatricians for a continued immunization (Weck 1986). 4 Although it took centuries, medical science finally caught up with the disease. In 1894 a plague epidemic broke out in the Yunnan Province of China.
Alexander Yersin, a 31-year-old Swiss pathologist who had traveled extensively in Indochina, arrived in Hong Kong hoping to identify the plague organism. Within seven weeks, he had succeeded in isolating and describing the bacterium. Yersin had discovered the plague-causing microbe that now bears his name: Yersinia pestis. 2) Robert Koch A German scientist and Nobel laureate, Robert Koch founded modern medical bacteriology, isolated several disease-causing bacteria, including those of tuberculosis, and discovered the animal vectors of a number of major diseases.
Koch’s first major breakthrough in bacteriology occurred in the 1870s, when he demonstrated that the infectious disease anthrax developed in mice only when the disease-bearing material injected into a mouse’s bloodstream contained viable rods or spores of Bacillus anthracis. Koch’s isolation of the anthrax bacillus was of momentous import, because this was the first time that the causative agent of an infectious disease had been demonstrated beyond a reasonable doubt.
It now became clear that infectious diseases were not caused by mysterious substances but instead by specific microorganisms—in this case, bacteria. Koch also showed how the investigator must work with such microorganisms, how to obtain them from infected animals, how to cultivate them artificially, and how to destroy them. He revealed these observations to the great German pathologist Julius Friedrich Cohnheim and his associates, one of whom was the German bacteriologist Paul Ehrlich, the founder of modern immunology.