How does the igm detect a recent exposture?

Hello Distress,

It seems that there is a lot of confusion out there when it comes to herpes testing.  One thing to keep in mind is that individuals vary, and this difference between people makes it sometimes difficult to determine how long ago an infection was acquired.  IgG can show up weeks after infection in some people, but can take months to show up in others.  IgM usually indicates a recent infection, but recent studies have shown that IgM can show up during recurrent outbreaks, so one can no longer assume that the presence of IgM means you have recently acquired herpes. 

With regard to your test, the lab may have found IgM and assumed the infection was recent, as IgM is generally the body's first response.  I don't know if the following would be true in your case, but sometimes doctors can take two blood samples (acute and convalescent, with the latter being taken weeks or months later) and compare the amount of IgG in both.  If there is a significant rise in the amount of IgG found in the convalescent sample, then it can be accurate to say the infection is recent, as the body is in the process of producing your life-long antibody for the virus.

Ultimately, how an individual responds to viruses like HSV makes it difficult to determine when one actually became infected.  The virus itself has evolved to be fairly mild and reclusive in most individuals, which is what makes it such an excellent sexually transmitted disease.  I have attached a link to a site that explains some forms of testing.  You could review this, and other sites like it, so you can talk with your doctor if you need to.  Hope this helps...

http://www.ashastd.org/herpes/herpes_learn_testing.cfm