Ignaz Semmelweis (born 1818 - died 1865) was a Hungarian doctor who discovered bacteria, disease and infection. He is the father of infection control. Semmelweis observed that if the doctors washed their hands, the number of infections of puerperal fever could be reduced. For this reason, Semmelweis ordered his medical students to wash their hands before and after medical rounds. He was mocked by fellow doctors, but he could not prove his findings, because bacteria had not been discovered yet. In 1870, Robert Koch proved that bacteria can cause disease. People such as Louis Pasteur proved what is known as the germ theory of disease only after Semmelweis' death.