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1876-1884Peer-reviewed · 2 sourcesWell documented

Koch's Postulates Prove Which Germs Cause Which Diseases

Robert Koch isolates the bacteria behind anthrax, tuberculosis, and cholera and sets a repeatable test for proving any microbe causes any disease

On the timeline · around 1876-1884 · The Birth of Vaccination and EpidemiologyThe Birth of Vaccination and EpidemiologyModern Pandemics and Modern MedicineKoch's Postulates Prove Which Germs Cause Which Diseases18001825185018751900

Quick facts

Key figure
Robert Koch
Anthrax
Bacillus anthracis isolated and postulates established, 1876
Tuberculosis
Mycobacterium tuberculosis announced March 24, 1882
Cholera
Vibrio cholerae isolated in pure culture, January 7, 1884
Legacy
Nobel Prize in Physiology or Medicine, 1905

What happened

Building on Pasteur's germ theory, the German physician Robert Koch set out to prove that specific germs caused specific diseases, rather than merely correlating with them. In 1876 he isolated Bacillus anthracis from the blood of anthrax-infected cattle, cultured it in the lab, and showed that injecting the pure culture into healthy mice reproduced the disease, establishing what became known as Koch's postulates: the organism must be found in every case of the disease, isolated in pure culture, shown to reproduce the disease when introduced into a healthy host, and re-isolated from that host. On March 24, 1882, Koch announced to the Berlin Physiological Society that he had identified Mycobacterium tuberculosis as the cause of tuberculosis, then the leading cause of death in Europe, after nearly six months of daily work isolating and culturing the slow-growing bacillus. In 1883 and early 1884 he traveled to Egypt and then Calcutta during a cholera epidemic, examined roughly 100 autopsies, and on January 7, 1884 isolated Vibrio cholerae in pure culture from contaminated water tanks, identifying its distinctive comma shape.

Why it matters

Koch's postulates gave medicine a repeatable, falsifiable test for linking a microbe to a disease, turning germ theory from a plausible idea into a working method that could be applied to any infection. Every pathogen identification in this timeline after 1876, from the plague bacillus in 1894 to modern viral sequencing, follows the logical framework Koch built with anthrax, tuberculosis, and cholera.

How we know

Koch published his tuberculosis findings in Die Atiologie der Tuberkulose in 1882 and his cholera findings in the Deutsche Medizinische Wochenschrift in 1884; contemporary accounts describe his Berlin lecture audience rising afterward to examine his bacterial cultures and slides directly.

Sources

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