Louis Pasteur (December 27, 1822 – September 28, 1895) was a French biologist, microbiologist and chemist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization. He is remembered for his remarkable breakthroughs in the causes and prevention of diseases, and his discoveries have saved many lives ever since. He reduced mortality from puerperal fever, and created the first vaccines for rabies and anthrax.

Rabies is a viral disease that causes inflammation of the brain in humans and other mammals. Early symptoms can include fever and tingling at the site of exposure. These symptoms are followed by one or more of the following symptoms: violent movements, uncontrolled excitement, fear of water, an inability to move parts of the body, confusion, and loss of consciousness.

Pasteur produced the first vaccine for rabies by growing the virus in rabbits, and then weakening it by drying the affected nerve tissue. The rabies vaccine was initially created by Emile Roux, a French doctor and a colleague of Pasteur, who had produced a killed vaccine using this method. The vaccine had been tested in 50 dogs before its first human trial. This vaccine was used on 9-year-old Joseph Meister, on July 6, 1885, after the boy was badly mauled by a rabid dog.

Anthrax is an infection caused by the bacterium Bacillus anthracis. It can occur in four forms: skin, lungs, intestinal, and injection. Symptom onset occurs between one day to over two months after the infection is contracted.

The skin form presents with a small blister with surrounding swelling that often turns into a painless ulcer with a black center. The inhalation form presents with fever, chest pain, and shortness of breath. The intestinal form presents with diarrhea which may contain blood, abdominal pains, nausea, and vomiting. The injection form presents with fever and an abscess at the site of drug injection. 

In the 1870s, he applied the immunization method that he experimented on chicken cholera to anthrax, which affected cattle, and aroused interest in combating other diseases. Pasteur cultivated bacteria from the blood of animals infected with anthrax. When he inoculated animals with the bacteria, anthrax occurred, proving that the bacteria was the cause of the disease. 

In early 1881, Pasteur discovered that growing anthrax bacilli at about 42 °C made them unable to produce spores, and he described this method in a speech to the French Academy of Sciences on February 28. Later in 1881, veterinarian Hippolyte Rossignol proposed that the Société d'agriculture de Melun organize an experiment to test Pasteur's vaccine. Pasteur agreed, and the experiment, conducted at Pouilly-le-Fort on sheep, goats and cows, was successful. 

His medical discoveries provided direct support for the germ theory of disease and its application in clinical medicine.

According to en.wikipedia