Polymerase Chain Reaction (PCR) is a technique in molecular biology by which a few DNA molecules can be duplicated into thousands or millions of copies of a special DNA sequence.

The direct detection of bacteria or viruses can be done by PCR technique from different materials from the human body (blood, urine, tissue etc.). In 1993, Mullis and M. Smith were awarded the Nobel Prize in Chemistry for their work on PCR.

The following tests for tick-borne diseases can be analyzed by PCR from blood (EDTA tube), spinal fluid, or biopsies: