Pasteur, Louis. Autograph letter signed (“L. Pasteur”), 1 page (8 x 5 ¼ in.; 224 x 133 mm.), in French, Paris, 11 February 1881, to an unidentified gentleman.
Pasteur on rabbits infected with rabies.
Pasteur explains he is working away on a rabies vaccine with rabbits and notes he is in need of new cages. He asks his correspondent if he might have permission to forward a letter he has received from Geneva relative to rabies. Pasteur explains his correspondent is more versed with the laws in Switzerland on experimentation there. He asks that his correspondent send his response directly to Geneva.
In 1880, Louis Pasteur applied his experimental method to the study of a human disease. He chose rabies because it affected not only humans, but also animals on which he could experiment. Because rabies is a disease of the nervous system, together with Emile Roux, he decided to inoculate part of a rabid dogs brain directly into another dog’s brain. The inoculated dog subsequently died. The experiment was then conducted on rabbits to reduce the risk to the scientists. After serial passage through several rabbits, the rabies incubation period was still six days. Pasteur had therefore produced a vaccine with stable virulence. He then attempted to develop a vaccine with attenuated virulence. He suspended sections of spinal cord from rabid rabbits inside flasks to dry in a moisture-free atmosphere. Virulence gradually declined until finally disappearing. He injected these spinal cord sections into rabid dogs, followed by preparations of increasing virulence. They did not develop rabies. He then established a protocol to fight the disease effectively.
On 25 February 1884, together with Charles Chamberland and Emile Roux, Louis Pasteur announced the discovery to the French Academy of Science, which appointed a study commission to assess the method’s efficacy. The method was deemed conclusive and approved.