Pasteur developed the first fowl cholera vaccine in 1880.
Pasteur’s work on fowl cholera began after he obtained bacterial samples associated with the disease. The breakthrough came when an old laboratory culture was used for inoculation and produced a milder illness than a fresh, highly virulent culture. The surviving chickens appeared protected when later exposed to more dangerous bacteria.
This observation led Pasteur and his assistants Émile Roux and Charles Chamberland to develop the idea of attenuation: weakening a disease-causing microorganism so it can stimulate protection without normally causing fatal disease. In February 1880, Pasteur presented early results on virulent diseases and chicken cholera to the French Academy of Sciences, and he announced work on the vaccine later that year.
The disease is now called fowl cholera or avian pasteurellosis and is caused by Pasteurella multocida. It is unrelated to human cholera, which is caused by Vibrio cholerae. Pasteur’s fowl-cholera vaccine did not produce immunity consistently, but the experiments were historically important because they helped launch the modern science of laboratory-attenuated vaccines.