Explanation

EBV IgG antibodies (VCA IgG): what is measured?

The Epstein-Barr virus (EBV) causes mononucleosis (glandular fever). After infection, the body makes antibodies against the coat of the virus (viral capsid antigen, VCA): first VCA IgM and shortly afterwards VCA IgG. VCA IgG usually stays detectable for life, just as the virus stays dormant in the body. The result is assessed together with VCA IgM and EBNA IgG.

What can it detect?

A past or ongoing EBV infection
No antibodies: probably never infected with EBV

Result

What does the result mean?

Positive result

A positive VCA IgG means you are or have been infected with the Epstein-Barr virus. Whether this was recent or long ago is shown by the other two tests: with a positive EBNA IgG and a negative VCA IgM it is an old infection, with a positive VCA IgM and a negative EBNA IgG probably a recent infection. A positive VCA IgG occurs in most adults and on its own is not an explanation for symptoms.

Negative result

A negative VCA IgG usually means you have not yet had the Epstein-Barr virus. Very early in an infection, VCA IgG can still be negative while VCA IgM is already positive. Because most adults have already had the virus, a negative result is not common in adults.

After an abnormal result

With a pattern that fits a recent infection, the illness usually clears up on its own and the GP mainly watches the course and looks out for rare complications. With an unclear pattern, the laboratory can do a confirmation test or the test is repeated after a few weeks. Mononucleosis is not notifiable.

Reliability

How reliable is the test?

According to the test guide of UMC Utrecht, the combination of VCA IgG and EBNA IgG is enough for the question of whether someone has had EBV; for the question of a recent infection, VCA IgM, VCA IgG and EBNA IgG are measured together. A single VCA IgG does not distinguish an old infection from a recent one. The pattern of the three tests can usually be interpreted well; with an unclear pattern, the laboratory can do an additional test.

What can affect the result?

Very early in the infection, VCA IgG can still be negative.
After a blood transfusion or treatment with immunoglobulins, antibodies from donors may temporarily be measured as well.
Test methods and cut-off values differ by laboratory.

Who it is for

Who is the test useful for?

Useful for

The result says the most with symptoms that fit mononucleosis, such as a sore throat, fever, swollen glands and marked tiredness, especially in teenagers and young adults, or to find out whether someone has already had the virus, for example before a transplant. In people without symptoms, and with long-lasting tiredness without such a clinical picture, a positive IgG says little, because most adults have already had the virus.

How common is it?

Infection with the Epstein-Barr virus is very common in the Netherlands: half of the population over 5 years old has had the infection, and most adults had it before the age of twenty, usually without noticing. In teenagers and young adults the infection more often causes symptoms, such as a sore throat, fever, swollen glands and tiredness that can last 2 to 3 months.

RIVM, mononucleosis (glandular fever)

Drawbacks and risks

A result that fits an old infection can wrongly be seen as the explanation for long-lasting tiredness, while it only shows a very common past infection.

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