What is the advantage of PCR and ELISA over conventional diagnostic methods.

Explanation

Presence of pathogens like virus, bacteria , etc., is detced only when the pathogen produces symptoms in the patient. By the time the symptoms appear, concentration of pathogen becomes very high in the body. However very low concentration of a bacteria or a virus. even when the symptoms of the disease does not appear, can be detected by amplification of their nucleric acid. Thus PCR and ELISA help in early diagnosis.