Mononucleosis diagnosis summary

Susceptibility

 * If antibodies to the viral capsid antigen are not detected, the patient is susceptible to EBV infection.

Primary Infection

 * Primary EBV infection is indicated if IgM antibody to the viral capsid antigen is present and antibody to EBV nuclear antigen (EBNA), is absent.


 * A rising or high IgG antibody to the viral capsid antigen and negative antibody to EBV nuclear antigen after at least 4 weeks of illness is also strongly suggestive of primary infection.


 * In addition, 80% of patients with active EBV infection produce antibody to early antigen.

Past Infection

 * If antibodies to both the viral capsid antigen and EBV nuclear antigen are present, then past infection (from 4 to 6 months to years earlier) is indicated.


 * Since 95% 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.

Reactivation

 * In the presence of antibodies to EBV nuclear antigen, an elevation of antibodies to early antigen suggests reactivation.


 * However, when EBV antibody to the early antigen test is present, this result does not automatically indicate that a patient's current medical condition is caused by EBV.


 * A number of healthy people with no symptoms have antibodies to the EBV early antigen for years after their initial EBV infection. Many times reactivation occurs subclinically.

Chronic EBV Infection

 * Reliable laboratory evidence for continued active EBV infection is very seldom found in patients who have been ill for more than 4 months.


 * When the illness lasts more than 6 months, it should be investigated to see if other causes of chronic illness or chronic fatigue syndrome (CFS) are present.

Resources

 * CDC Mononucleosis