Question

Koch’s postulates are not applicable to
A) T.B
B) Leprosy
C) Cholera
D) Diphtheria

Answer 1

Hint:Koch's postulates: In 1890, Robert Koch, a German physician and bacteriologist, set forth his celebrated criterion for determining whether a given bacteria is the cause of a given disease. Koch's criteria also provided some much-needed scientific clarity to what was then a somewhat confused area.

Complete answer:
The postulates of Koch are as follows:
>In any case of the disease, the bacteria must be present.
>The bacteria must be isolated from the disease host and grown in pure culture.
>When the pure culture of the bacteria is inoculated into a healthy susceptible host, the same disease has to be replicated.
>The bacteria must be retrieved from the experimentally contaminated host.

However, Koch's postulates have drawbacks, so it might not always be the last word. They will not be retained if:
>Specific bacteria (such as the one that causes leprosy) can not be "grown in pure culture" in the laboratory.
>There is no animal model of infection with this particular bacteria.

An inoffensive bacteria can cause disease if:
>It has acquired extra virulence factors that make it pathogenic.
>Access to deep tissue by trauma , surgery, IV line, etc.
>Infects the immunocompromised patient.
>Not all bacteria infected individuals may develop a disease. In general, subclinical infection is more common than a clinically evident infection..

Hence the correct answer is ption (B) Leprosy.

Note:Despite these limitations, Koch's conclusions are still a valuable benchmark in determining if there is a cause-and - effect relationship between a bacteria (or any other form of microorganism) and a clinical disease.