[Worldkings] Top 50 inventions and discoveries made by accident (P. 28) Louis Pasteur discovered the chicken cholera vaccine when his assistant accidentally exposed the bacteria to oxygen for a long time


(Worldkings.org) The chicken cholera vaccine was accidentally developed by the French biologist and microbiologist Louis Pasteur in the mid-1800s.

Louis Pasteur (December 27, 1822 – September 28, 1895) was a French chemist and microbiologist best known for his discovery of the chicken cholera vaccine. At that time, chicken cholera was a serious disease that caused high mortality rates among domestic fowl and had a significant impact on the poultry industry.


By 1878, Pasteur had succeeded in culturing the causative virulent bacteria of chicken cholera and began inoculating chickens. However, many chickens died after the procedure so Pasteur continued to study the disease, looking for safer inoculation methods. It was during this study that Pasteur changed the field of virology forever.

In 1879, Pasteur observed, by chance, that old bacterial cultures lost their virulence. He had instructed an assistant to inject the chickens with a fresh culture of the viral bacteria before a holiday. The assistant, however, forgot and went on vacation. When he returned a month later, he performed the procedure using the old cultures. Unexpectedly, the chickens only showed mild signs of the disease and survived. When they were healthy again, Pasteur, intrigued by the results, injected them with fresh bacteria. The chickens did not become ill. Pasteur reasoned the factor that made the bacteria less deadly was exposure to oxygen.


The microbe, weakened in the lab, had taught the chicken immune system to fight the infection without causing any serious harm to the chicken. This type of vaccine is called a live, attenuated vaccine.

The discovery of the chicken cholera vaccine by Louis Pasteur revolutionized work in infectious diseases and can be considered the birth of immunology. The notion of using a weakened form of the disease to provide immunity was not new, but Pasteur was the first to take the process to the laboratory, impacting all virologists who followed after him.


According to vbivaccines.com & Wikipedia

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