Syn: Koch's postulates. First formulated by the German pathologist Friedrich Gustav Jacob Henle (1809–1885) and adapted and modified by the German bacteriologist Robert Koch (1843–1910), these are four criteria that usually suffice to confirm the causal relationship of a pathogenic organism to a specific infectious disease. The postulates are: 1. The agent must be demonstrable in every case of the disease; 2. The agent is not present in other diseases; 3. After isolation in culture, the agent must be able to produce the disease in experimental animals; and (added by Koch) 4. The agent can be recovered from the experimental animal. All four postulates can be demonstrated with many bacterial diseases but have not been confirmed in some in which a causal connection may have to be inferred from other evidence, e.g., HIV/AIDS.
1. The agent must be demonstrable in every case of the disease; 2. The agent is not present in other diseases; 3. After isolation in culture, the agent must be able to produce the disease in experimental animals; and (added by Koch) 4. The agent can be recovered from the experimental animal. All four postulates can be demonstrated with many bacterial diseases but have not been confirmed in some in which a causal connection may have to be inferred from other evidence, e.g., HIV/AIDS.
