Can a disease be detected before its symptoms appear? Explain the principle involved.

Explanation

When the symptoms of the disease are not visible and the pathogen concentration is very low, then detection by conventional diagnostic tests is very difficult. However, detection at the above stated stage is made possible by molecular diagnostic techniques like the amplification of their nucleic acid by Polymerase Chain Reaction (PCR). The principle involved here is that a single DNA molecule can be copied endlessly in a test cube, using primers, DNA polymerase enzyme and free nucleotides and appropriate conditions.