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1860s-1880s (Pasteur); 1882 (Koch's tubercle bacillus)Peer-reviewed · 2 sourcesWell documented

Pasteur and Koch Prove Germs Cause Disease

A French chemist and a German physician replace bad air and imbalance with a specific microbe for a specific illness

On the timeline · around 1860s-1880s (Pasteur); 1882 (Koch's tubercle bacillus) · Germ Theory and Modern MedicineGerm Theory and Modern MedicinePasteur and Koch Prove Germs Cause Disease1850187519001925

Quick facts

Pasteur
Germ theory, pasteurization, rabies vaccine (1885)
Koch's tubercle bacillus
Presented March 24, 1882
Koch's postulates
Rules for proving a microbe causes a disease
Koch's Nobel Prize
1905

What happened

Over the second half of the 19th century, two researchers turned the germ theory of disease from a minority idea into established science. Louis Pasteur showed that microorganisms caused both fermentation and disease, that heating could kill the spoiling microbes in wine, an insight that became pasteurization, and on July 6, 1885 he treated his first human rabies patient, nine-year-old Joseph Meister, with a vaccine, saving him. Robert Koch supplied the rigor. On March 24, 1882 he presented his discovery of the bacterium that causes tuberculosis, and he set out the standard, later called Koch's postulates, for proving a specific microbe causes a specific disease: it must be present in every case, absent in other conditions, and able to reproduce the disease when isolated, cultured, and introduced into a healthy animal. Koch received the Nobel Prize in 1905 for this work.

Why it matters

Germ theory is the hinge of modern medicine. Once disease could be tied to identifiable microbes, it became possible to prevent infection through sterilization and sanitation, to attack it with targeted vaccines and, later, antibiotics, and to reason about outbreaks in terms of transmission. Nearly everything that follows in this timeline, antisepsis, vaccines, antibiotics, public health, rests on the foundation Pasteur and Koch laid.

How we know

Pasteur's experiments and the 1885 rabies treatment, and Koch's 1882 tuberculosis discovery, his postulates, and his 1905 Nobel Prize, are documented in their own publications and lectures and in institutional and peer-reviewed histories of microbiology.

Sources

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