IgM and IgG Tests for Chicken Pox

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Posts: 1
Joined: Mon Aug 08, 2005 11:56 pm
Location: New Orleans, LA

IgM and IgG Tests for Chicken Pox

Postby emsmom » Tue Aug 09, 2005 12:29 am

My daughter has recently been exposed to Chicken Pox. She has not had the Chicken Pox vaccine (medical exemption from pediatrician) due to a family history of neurologic disorders.

Since it has an appx 21 day incubation period and she is starting school prior to the end of this period, we wanted to find out if, in fact she was incubating Chicken Pox. I would hate for her to miss the 1st week of school if it's not necessary. And I don't want to take a chance on infecting other children at school either. So, the pediatrician did an IgM and IgG test. The IgG test came back negative, meaning, from my understanding, that she does not have antibodies, or, in other words, an immunity to Chicken Pox. The IgM came back at .91. The way that it was explained to me was that if the number falls in the range of .90 - 1.10(I believe) it would put her in the category of "possibly" having a recent exposure. The lab called the IgM "indeterminant." I don't understand what this means. Does it mean that she is in the beginning stages of it and, that, maybe when we administered the test, it was too early to determine and the anitbodies were just developing? I know that not everything is black and white, but, I know she can't "sort of " have the Chicken Pox. Could it also be that this .91 does indicate a response from her immune system, but doesn't necessarily mean that she would be affected by it or come down with it?
Most importantly, I would like to have a 2nd test done now. Wouldn't the 2nd test be more valid now that she's several more days into the incubation(if, in fact, she is incubating it?) This 2nd test seems to be the answer. If I could test her, which she is more than willing to do (she's very upset that she may have to miss the 1st week!), how would the time frame (of about 6 days later) affect the results? WOuld this work?
Just an FYI,,,the exposure date was around July 31st. It was her brother. I know you probably think that I'm crazy, but I separated my kids, in separate houses, through my son's contagious period. Also, interesting side note, the initial exposure that my son had in which he contracted the Pox was from a child that my daughter had sleep over. In the middle of the night the child woke up with a fever, then proceeded to break out in the am. My daughter played with this child all night, my 3 yr old son, about 3 times, had to go in the room where they were playing and tear up the "Barbie world" that the girls had created! HE develops Chicken Pox, while my daughter escaped this 1st 21 day incubation period! The Dr was amazed! Hence the reason for the IgG...the Dr thought that, maybe she had an immunity to it. But, apparently not.

Anyway, would a 2nd test be beneficial?

Thank you so much for reading this through! I know that I was long winded, but I just wanted you to have all of the facts.

Dr. Heba Ismail
Medical Doctor
Posts: 328
Joined: Tue Sep 21, 2004 4:08 am

Postby Dr. Heba Ismail » Fri Aug 12, 2005 9:29 am

Testing for varicella zoster virus (VZV), the virus causing chicken pox, IgM antibodies is not useful for clinical diagnosis as commercially available methods are unreliable. A capture IgM assay is available at the national VZV laboratory at the Centre for Disease Control (CDC).
VZV IgG antibodies can be detected by several methods and a 4-fold rise in IgG antibodies is confirmatory of acute infection.
Best regards,

Dr. Heba Ismail, M.D.

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