Low Positives / False Positives

[hugo313]

It appears from what I've read that people who are HSV-1 positive and have a low positive HSV-2 score (>1.1 to 3.5) have a better chance of the HSV-2 low positive being a false positive.  I've seen the graph (figure 1) within http://www.biomedcentral.com/1471-2334/5/84  which seems to indicate that if I have an HSV-2 score of 1.4 (which i do)---then the chance of being a false positive are at about 85%.  How are these percentages affected if one is NOT HSV-1 positive?    I'm trying to understand the significance.  Are most HSV-2 false positives from those with HSV-1?  Or is there really no significant correlation?

[Edward W Hook, MD]

While persons who have HSV-1 antibodies appear to be more likely to have false positive HerpeSelect tests for HSV-2 than those who do not have HSV-1 antibodies, persons who do not have HSV antibodies also relatively commonly have false positive tests for HSV-2 as well.  There are not precise estimates on how frequently this occurs but it is more common than not.  Bottom line, if you have not had typical lesions or other finings highly suggestive of genital herpes and you have a low positive test, it is more likely to be a false positive than not. If you want/need further clarification, the most widely accepted test for resolving discrepancies is the Western Blot assay performed at the University of Washington.  EWH

[Edward W Hook, MD]

Your assessment is correct. EWH

[hugo313]

Dr. Hook--
Thank you for your reply.  That certainly helps put things into perspective, and now I have a better understanding.   So I guess as it relates to that graph I referenced above---it really doesn't distinguish 1) between people with symptoms with those who don't have symptoms and likewise 2) doesn't distinguish if you have a positive HSV-1?  Just the general odds based on the particular score thresholds?

Thanks again.