What is the Varicella-Zoster Antibody, IgG test?
This test looks for antibodies in your blood that your body makes against the varicella-zoster virus.
The varicella-zoster virus is very contagious and can cause 2 health problems:
- chickenpox and
When you become infected with the virus for the first time, it causes chickenpox. After having chickenpox, most people become immune to the virus for the rest of their life. They can’t get chickenpox again.
Symptoms of chickenpox include:
Distinctive rash around the body a day or two after other symptoms begin
The rash lasts for about two weeks. It can spread until all the spots on the skin have crusted over.
But after the first illness, the virus becomes dormant and “hides” in nerves in your body. Later in your life, the virus can become active again. It causes a painful rash called shingles (aka herpes zoster.)
What do results mean?
If testing is done to see if you are at risk of developing an infection and it finds varicella-related immunoglobulin G (IgG) antibodies in your blood, it means you are immune. You have had a chickenpox infection or have been immunized successfully.
If your healthcare provider suspects that you have chickenpox, your IgG levels can mean you have an infection if they rise over several weeks. In these cases, this test is usually needed only if your provider is unsure about the diagnosis after examining you.
Vaccinated: positive (> or =1.1 AI)
Unvaccinated: negative (< or =0.8 AI)
A positive result indicates that the you have antibody to VZV but does not differentiate between an active or past infection. The clinical diagnosis must be interpreted in conjunction with the clinical signs and symptoms.
Twenty percent of adults will develop shingles, a rash or blister of the skin that may cause severe pain. Varicella-Zoster IgG, EIA reliably measures immunity due to previous infection, but is unsuitable for detection of post-vaccination immune status.
- Yankowitz J, Grose C: Congenital infections. In Essentials of Diagnostic Virology. Edited by GA Storch. Churchill Livingstone, New York, 2000, pp 187-201
- Gnann JW, Whitley RJ: Herpes Zoster. N Engl J Med 2002;347:340-346
- Cvjetkovic D, Jovanovic J, Hrnjakovic-Cvjetkovic I, et al: Reactivation of herpes zoster infection by varicella-zoster virus. Med Pregl 1999;52(3):125-128
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