$PCR$ is a useful tool for the early diagnosis of an infectious disease. Elaborate.

(N/A) $PCR$ (Polymerase Chain Reaction) is a highly sensitive technique that allows for the specific amplification of a target $DNA$ sequence from a very small amount of $DNA$ template. Because of this high sensitivity,it can detect the presence of pathogenic organisms in an infected patient at a very early stage of infection,even before the pathogen has multiplied to a large number in the host's body.