Serologic Interpretation: This Patient Does NOT Have Acute Infectious Mononucleosis
This 17-year-old female does not have acute infectious mononucleosis based on her serologic profile. The presence of positive EBNA (Epstein-Barr nuclear antigen) with negative IgM indicates past EBV infection, not current acute disease 1, 2.
Understanding the Serologic Pattern
Why This is NOT Acute Mononucleosis
EBNA positivity is the key finding that excludes acute infection - EBNA antibodies appear late in EBV infection (typically 3-6 months after acute illness) and persist indefinitely, indicating remote past infection 2
The diagnostic pattern for acute IM requires: positive VCA IgM, positive or negative VCA IgG, and absent EBNA 1, 2
Her positive EBNA with negative IgM demonstrates she had EBV infection in the past (likely months to years ago) and has developed immunity 1
What the Positive VCA IgG Means
VCA IgG >8.0 without accompanying IgM indicates past infection rather than acute or recent infection 1
This pattern (positive VCA IgG + positive EBNA + negative IgM) represents remote past EBV exposure with established immunity 2
Clinical Implications and Next Steps
Alternative Diagnosis Required
Her current 3-week illness of sore throat and fatigue must have another cause since the serology excludes acute mononucleosis 3
Consider other etiologies including:
When Heterophile Testing Would Have Been Useful
The heterophile antibody test has 87% sensitivity and 91% specificity for acute IM but can be false-negative in the first week of illness 3
In this case, a heterophile test would likely have been negative given the serologic pattern showing past rather than acute infection 4
Important Caveat About Chronic Active EBV
The guidelines you're seeing about chronic active EBV (CAEBV) are not applicable here - CAEBV requires persistent IM-like symptoms, unusual antibody patterns with markedly elevated VCA and EA titers (VCA-IgG ≥1:640, EA-IgG ≥1:160), and exclusion of other diseases 6
CAEBV is a rare, serious condition characterized by chronic symptoms (persistent fever, lymphadenopathy, hepatosplenomegaly) lasting months, not the 3-week presentation described here 6
Management Recommendation
Reassess for alternative diagnoses - repeat throat culture or rapid strep testing, consider monospot if not already done (though expect negative result), and evaluate for other causes of prolonged pharyngitis and fatigue 4, 5. The positive EBNA definitively rules out acute mononucleosis as the cause of her current symptoms 1, 2.