From the Guidelines
Retesting for mononucleosis in a patient with a history of mono who is currently symptomatic is generally not recommended. Once a person has had mononucleosis, caused by the Epstein-Barr virus (EBV), they develop antibodies that typically remain positive for life, making repeat testing unhelpful for diagnosing a new illness 1. Instead, focus on evaluating the current symptoms and consider alternative diagnoses. The patient's symptoms may be due to another condition such as strep throat, influenza, COVID-19, or another viral or bacterial infection.
- Key points to consider:
- EBV antibodies, such as VCA IgG and EBNA, remain detectable for life in over 90% of the normal adult population 1
- The presence of EBNA antibodies indicates infection more than 6 weeks from the time of the sample and therefore not likely implicating EBV as a cause 1
- EBV can occasionally reactivate but rarely causes significant symptoms in immunocompetent individuals
- If the patient is experiencing severe fatigue, sore throat, fever, or lymphadenopathy similar to their previous mono episode, appropriate testing should be directed toward these alternative causes. For patients with persistent fatigue after mono, consider chronic fatigue syndrome or other underlying conditions rather than EBV reactivation 1. Management should focus on symptomatic treatment and identifying the actual cause of the current symptoms.
From the Research
Retesting for Mononucleosis
If a patient has a history of mononucleosis and is symptomatic, the decision to retest should be based on the clinical presentation and the timing of the symptoms.
- The patient's symptoms and medical history should be evaluated to determine if retesting is necessary 2.
- The heterophile antibody test has a sensitivity of 87% and specificity of 91%, but can have a false-negative result in certain cases, such as in children younger than five years and in adults during the first week of illness 2.
- Epstein-Barr viral capsid antigen-antibody testing is more sensitive and specific, but more expensive and takes longer to process than the rapid heterophile antibody test 2.
Diagnostic Tests
The following diagnostic tests can be used to diagnose infectious mononucleosis:
- Complete blood count with differential to assess for greater than 40% lymphocytes and greater than 10% atypical lymphocytes 2.
- Rapid heterophile antibody test, which has a sensitivity of 87% and specificity of 91% 2.
- Epstein-Barr viral capsid antigen-antibody testing, which is more sensitive and specific but more expensive and takes longer to process 2.
- Plasma EBV-DNA test, which has a higher diagnostic value than the VCA-IgG avidity test in children aged <6 years, especially aged <3 years 3.
Considerations for Retesting
The decision to retest for mononucleosis should take into account the following considerations:
- The patient's age and immune status, as immunosuppressed populations are at higher risk of severe disease and significant morbidity 2.
- The timing of the symptoms, as the heterophile antibody test can have a false-negative result in adults during the first week of illness 2.
- The results of previous diagnostic tests, such as the complete blood count with differential and the rapid heterophile antibody test 2.
- The presence of elevated liver enzymes, which can increase clinical suspicion for infectious mononucleosis in the setting of a negative heterophile antibody test result 2.