Accidental discovery of Vaccine, that prevent disease
Vaccination is a general method for preventing infectious diseases. It is first accidentally discovered by Pasteur & is occurred during Pasteur’s struggle to establish the germ theory of disease, specifically in the case of chicken cholera. To demonstrate that chicken cholera was caused by germs and not some toxins in the blood, it was important to isolate germs from toxins, which was very difficult in those early days. To purify germs, Pasteur extracted them from diseased chickens, grew them in cultures outside the body, and injected the culture into healthy chickens, which would become sick and a new source of germs, hopefully less contaminated with toxins. An autumn day in 1879, he injected a culture into some chickens and found them to be hardly affected. Later, because of a mix up or shortage of supply, the “used” chickens were recycled, together with some new chickens, in experiments to test a fresh virulent culture. This time the new chickens all died but the lucky recycled chickens remained unscathed. A colleague recalled that when Pasteur heard of this surprising development, he “remained silent for a minute, then exclaimed as if he had seen a vision: ‘Don’t you see that these animals have been vaccinated!
