Epstein Barr Virus p18 (IgG)

EBV antibody tests are not usually needed to diagnose infectious mononucleosis. However, specific antibody tests may be needed to identify the cause of illness in people who do not have a typical case of infectious mononucleosis or have other illnesses that can be caused by EBV infection. Symptoms of infectious mononucleosis generally resolve within four weeks. If a person is ill for more than six months and does not have a laboratory-confirmed diagnosis of EBV infection, other causes of chronic illness or chronic fatigue syndrome should be considered.

The interpretation of EBV antibody tests requires familiarity with these tests and access to the patient’s clinical information.

Interpretation of EBV antibody tests and diagnosis of EBV infection is summarized as follows:

• Susceptibility to infection
  People are considered susceptible to EBV infection if they do not have antibodies to the VCA.
• Primary (new or recent) infection
  People are considered to have a primary EBV infection if they have anti-VCA IgM but do not have antibody to EBNA. Other results that strongly suggest a primary infection are a high or rising level of anti-VCA IgG and no antibody to EBNA after at least four weeks of illness. Resolution of the illness may occur before the diagnostic antibody levels appear. In rare cases, people with active EBV infections may not have detectable EBV-specific antibodies.
• Past infection
  The presence of antibodies to both VCA and EBNA suggests past infection (from several months to years earlier). Since over 90% of adults have been infected with EBV, most adults will show antibodies to EBV from infection years earlier. High or elevated antibody levels may be present for years and are not diagnostic of recent infection.

Testing paired acute- and convalescent-phase serum samples is not useful to distinguish between recent and past EBV infections. In most cases, the antibody response occurs rapidly during primary EBV infection. The clinical findings of infectious mononucleosis occur in conjunction with the appearance of IgG and IgM anti-VCA antibodies. However, the antibody pattern is not stable before symptoms appear.

The Epstein–Barr virus, also called human herpesvirus 4 (HHV-4), is one of the causes of infectious mononucleosis (glandular fever). It is a double-stranded, enveloped, linear DNA virus. Lyme disease and infectious mononucleosis are common illnesses that share similar clinical presentations and hence its useful to test together.