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Herpes Testing
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Herpes Testing

My questions relates to herpes testing.  5 1/2 weeks after possible exposure and infection my doctor had herpes antibody tests performed.  (I had irritation but no visible sores.)  He has informed me that the tests came back positive for both Type 1 and Type 2 IgG antibodies. (He cautioned that the test is subject to cross-reaction.)  He has also informed me that the tests came back negative for both Type 1 and Type2 IgM antibodies, so he does not think that the possible exposure 5 1/2 weeks prior to testing led to an infection.  My questions are:  

1.  How quickly do IgM antibodies disappear?  (I have read that they can persist for up to one year.)  

2.  Is it possible that a test performed 5 1/2 weeks after actual infection would come up negative for IgM antibodies?  

3.  If so, is there any way to gauge how likely it is that a test taken 5 1/2 weeks post-infection would have a negative IgM result?  

4.  Finally, how common is cross-reaction with HSV antibody tests?  (I unfortunately do not know specifics on the type of test used.)

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I'm afraid I don't have the specific information you are seeking.  Among other things, the answers depend on the sensitivity of the tests performed in the particulat laboratory your doctor used.  You may want to contact the lab and ask if they have any data bearing on the subject.  The same is true about your question concerning cross-reactivity.

If you have Herpes 2 antibodies, that suggests you were exposed to the virus at some time in the past--it doesn't mean you had it recently, or necessarily that you have any active herpes lesions.  If you were already exposed, you might not get IgM antibodoes even if you had a fresh attack.  In truth, however, I have never seen any data bearing on that point.

Whether you're able to get answers from the lab or from an expert in Infectious Diseases, in practical terms you would need to wait for a visible outbreak to tell whether you actually have herpes.  If you get sores or blisters, I suggest you see your doctor at once-- a culture at that time is the only thing I can think of that will be definitive.


Dr. Rockoff
If you have antibodies for HSV of either type, you actually have the virus somewhere in your body, not simply that you have been exposed to it.

The scenario you present would be typical of existing infections and not something as recent as 5 1/2 weeks, BUT, we have learned that the only thing typical about herpes is that there is nothing typical for many people. At 5 1/2 weeks after infection, I would expect to see IgM rather than IgG, but a significant percentage of folks do seroconvert (develop antibodies) for IgG within that time. The commonly quoted 12 to 16 weeks is the time span to get something like 75% of the infected people seroconverted.

What test did you have? The gold standard for blood tests is the Western Blot available through the University of Washington. This test can be ordered by any doctor or clinic. If your doctor is reluctant to go to the trouble, there are ways you can get the test if a doctor will give you an order for a blood draw.

In closing, I would recommend that playing "The Blame Game" if that's where these questions are headed, can only be destructive as this sneaky little virus can easily mislead everyone, including doctors. Feel free, if you are looking for support or more information, to visit our website at


The IgM tests that are available now are neither type specific (that is, differentiating between HSV 1 and 2) nor are they always virus specific, that is, they could mix up varicella with simplex, and not infrequently do.

The IgM has traditionally be used to try to separate out old
infection from new infection, because IgM goes away over time and shows up early with many viruses. However, with herpes simplex, it is present with about 35% of recurrences, so it doesn't help sort out new infection from old infection either.

The index values on the HerpeSelect are useful only in making certain that the test is a true positive. Dr. Rhoda Ashley Morrow at the UW, who developed the western blot, says she is comfortable with test results over 3.5 being accurate positives. Anything under 3.5 should be confirmed with another test, preferrably western blot. However, if the test is done too early in an infection, it could have a low value because it is in the process of climbing, and just isn't there yet. See what I mean? Optimally, 3 months should pass before testing if you are only going to test once. Differences in values between say 5
and 7, have more to do with the controls (established positive and negative values) that are being used for that particular test run. They have no meaning in terms of immune function,etc.

Rajah asked you if you knew which herpes test you had done.
I too am curious to know which test was done.

Hang in there ~


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