1. The Germ Theory of Disease
1876: Robert Koch proved that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, to prove that a specific microbe causes a specific disease
Figure 1.4

2. Koch's Postulates Postulate 1
The suspected pathogenic organism should be present in all cases of the disease and absent from healthy animals
Postulate 2
The suspected organism must be isolated and grown in a pure culture

3. Postulate 3
Cells from a pure culture of the suspected organism should cause disease in a healthy animal
Postulate 4
The organism must be re-isolated and shown to be the same as the origninal

4. Using Koch’s Postulates
1882 – bacteria caused tuberculosis
1884 – bacteria caused cholera
1884 – bacteria caused Diphtheria
1884 – bacteria caused Typhoid Fever
1885 – bacteria caused Gonorrhea
1886 – bacteria caused pneumonia
Etc.
2003 – Virus called SARS