Few scientists have saved as many lives as Louis Pasteur. His microbial theory led to the development of effective hygiene methods, vaccines and, later, antibiotic drugs. The unexpected trajectory of this chemist marked the birth of modern medicine and transformed our world forever.
Frenchman Louis Pasteur (December 27, 1822 – September 28, 1895) was a student who only stood out after graduating in science from the prestigious École Normale Supérieure in Paris, where he later became the director of scientific studies. Interested in the fermentation processes of wine and beer, he demonstrated that they take place because of the presence of microorganisms, and that these were also responsible for these alcoholic beverages becoming sour over time. That insight led him to develop in 1864 a method to sterilize them by heating them gently to eliminate bacteria after having completed their task of fermenting: the famous pasteurization, which is still applied today in the production of dairy products and many other beverages and foods, to improve their conservation and safety.
His solution to the contamination of beverages soon led Pasteur to the idea that infectious diseases are also caused by microorganisms, with the ability to spread among individuals. He was not the first to posit the germ or microbial theory of disease, but his experiments around 1870 were definitive in proving that it was correct. As a result, doctors like Joseph Lister began to apply antiseptic methods in their operations. After this great success, Pasteur dedicated the rest of his career to the fight against infectious pathologies, and in that effort he developed new and more effective vaccines.
The first rabies vaccine
In 1879, when he was 57 years old, he found that it was possible to protect himself from some infections thanks to the injection of attenuated germs. After numerous tests on sick animals—such as chickens that suffer from cholera—in 1885 he dared to give a rabies vaccine to Joseph Meister, a 9-year-old boy who had been bitten by an infected dog. After several days of inoculations, Pasteur managed to save him. In the following months he treated thousands of rabid dog bite victims in the same way.
Encouraged by the good results, he applied the principle of pathogen attenuation to prepare other vaccines, such as the anthrax vaccine. At the end of the 19th century, the foundations were laid for modern vaccinations, which have saved hundreds of millions of lives since then.
To meet the growing demand for vaccines, Pasteur promoted the creation of an institute to investigate infectious diseases, which finally opened in Paris under his name in 1888. The Pasteur Institute soon became the hub of the new science of microbiology, welcoming doctors and researchers from all corners of the world, who later returned to their places of origin with new knowledge and tools to fight diseases that shortly before had been incurable.
His disciples and the Pasteus institutes
Among Pasteur’s disciples, Émile Roux stood out. Pasteur’s main collaborator in the development of the anti-rabies vaccine, he travelled to Egypt in 1883 to study a cholera outbreak, although he was not able to isolate the pathogen that caused it, which was later discovered by the famous Robert Koch. That same year, however, he began to study diphtheria, for which he was able to develop an effective serum with the collaboration of another of Pasteur’s students, Alexandre Yersin. This Swiss scientist would go down in history for discovering in Hong Kong the bacterium responsible for the bubonic plague, which received the name Yersinia pestis. He undertook other studies in the Indochina peninsula, where he founded the first overseas Pasteur Institute in 1905.
Another outstanding “apostle” of Pasteur’s knowledge was Albert Calmette, who became the head of the Pasteur Institute in Saigon, where he devoted much of his time to the new-born field of toxicology, studying the properties of the toxins of snakes or bees.
Pasteur, who had lost three of his five children to typhoid fever infections, founded what would become a network of key institutes to control or eradicate diseases such as plague, diphtheria, tetanus, tuberculosis, polio, influenza or yellow fever. The story of Joseph Meister, the child saved by the rabies vaccine, continued to be linked to Pasteur. Throughout his life, Meister worked as a watchman in the first of the many institutes that would be created, and in which important discoveries have been made.
In 1983, the Paris headquarters was the laboratory that managed to isolate HIV, the virus that causes AIDS. Today, the Pasteur institutes are a network of high-level research facilities with more than 30 centres in countries on five continents. Nobel Prizes in Physiology or Medicine Eight have been awarded to eight scientists from these institutes.
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