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Medicine and Disease

Spaneous Generation

What was the “germ theory”?

The germ theory, established in the mid-1800s, posited that certain germs cause diseases, refuting the ages-old notion of spontaneous generation. The idea was first put forth by French chemist and microbiologist Louis Pasteur (1822–1895) in a paper he published in 1861. His research, and that of German physician Robert Koch (1843–1910), eventually substantiated the germ “theory” as fact: They proved that the microbe, or germ, is a living organism that can cause disease. Koch was even able to isolate certain bacteria as the causes of particular diseases, including anthrax (for which he published a method of preventive inoculation), tuberculosis, cholera, and rinderpest (a cattle disease). The anthrax germ was the first germ linked to a particular disease—by Koch in 1876. By the end of the 1800s researchers had discovered the kinds of bacteria and other microbes responsible for the plague, diphtheria, dysentery, gonorrhea, leprosy, malaria, pneumonia, tetanus, and other infectious diseases.