For many years people died of diseases and no one knew why. It was many years before scientists realized that the causes of most diseases were microorganisms, or germs. They began to study ways to fight these microscopic disease causing creatures.
In 1796 Edward Jenner discovered a safe and sure way of preventing a terrible epidemic disease called smallpox. He laid the groundwork for the science of immunology by using cowpox vaccine to inoculate against smallpox.
Louis Pasteur, a French scientist, uncovered important facts about bacteria during the 1800's . He invented the process of pasteurization, or heating to kill microorganisms, and developed vaccines for several diseases including, rabies.
A German doctor named Robert Koch proved that bacteria causes a lot of diseases. Robert Koch discovered a number of major diseases. In 1882 Koch isolated a bacillus that was the germ that cause tuberculosis.
The word virus was not used until the 1800s when scientists described germs that caused diseases that were smaller than bacteria.
Penicillin, is a powerful drug used to treat infections caused by bacteria. It was the first antibiotic (drug produced by microbes) used successfully in the treatment of serious diseases in human beings. Sir Alexander Fleming, a British scientist, discovered penicillin in 1928.
Many germs can be used to make vaccines to protect people from getting certain diseases.