hsv pcr dna question

I had a hsv pcr dna blood test at 10 weeks post exposure. My IgG at 6 weeks was negative but I didn't want to wait any longer for the antibodies to develop because I understand it takes time. The results were no hsv type 1 and 2 detected. 1) Is this result reliable? 2) For an initial infection, would hsv dna be detected in blood? I haven't had any symptoms since the exposure.

[H. Hunter Handsfield, M.D.]

Are you sure it was an HSV PCR test?  PCR is designed to detect the virus itself and is used to test lesions or other suspected sites of infection.  HSV does not normally circulate in the blood and I have never heard of it being used to test blood.  Even if a blood PCR is negative, that certainly would not rule out HSV infection, whether acute or chronic.

The negative antibody test at 6 weeks is moderate reassurance you weren't infected; probably around 50-60% of newly infected people would show positive by then.  However, the combination of no symptoms plus a negative antibody test at 6 weeks is at least 90% reliable.  For the blood test itself, you need to test at 12-16 weeks to achieve 90-95% assurance.

Good luck--  HHH, MD

[pcrguy]

Thank you for your comments doctor. Science has proven that HSV DNA can in fact be detected in the blood. However, the extent to which the virus may be present in the blood during active infection (acute or chronic)is unknown (reference NCBI) and thus the test is not conclusive. The specimen usually includes CSF, vesicle swab, tissue, and until recently whole blood. The test has a history of diagnosing HSV encephalitis and meningitis but studies have shown it effective among neonates and patients with acute and recurrent active infection. Interesting stuff but like many other tests still unreliable. I find advances in medical technology fascinating.

[H. Hunter Handsfield, M.D.]

I am entirely aware of all that, and did not think it pertinent to go into details for use in diagnosing complicated and systemic HSV infections, for which PCR is a mainstay of diagnosis.  There is no legitimate use of PCR on blood in the clinical situation you described.

[poonam09]

A related discussion, HSV PCR- Blood or CSF was started.