The French research chemist Louis Pasteur continued Jenner’s work with vaccination. Vaccinations work by presenting a foreign antigen to the body’s immune system in order to evoke an immune response. Pasteur reasoned that if a vaccine could be found for smallpox, then a vaccine could be found for all diseases. In the summer of 1880, he accidentally found a vaccine for chicken cholera, a disease that affected many poultry farmers. He also found a vaccine for rabies, a disease that affected animals and that humans contracted after being bitten by infected animals, mainly dogs. Pasteur and his research team discovered that the rabies germ attacked the nervous system only after it had made its way to the brain. The team traced the germ to the brain and spinal cord of infected animals and by using dried spinal cords, produced a vaccine for rabies. The vaccine was first tried out on animals, and in 1885 it was used successfully on a young boy who was bit by a rabid dog.