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EBV Infectious Mononucleosis — RACP Adult Medicine MCQ

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EasyInfectious DiseasesEBV Infectious MononucleosisRACP Adult Medicine

A 30-year-old man presents with a 4-day history of fever, sore throat, and a diffuse maculopapular rash. He has generalised lymphadenopathy. Monospot test is negative. Blood film shows reactive lymphocytes. He is HIV negative. EBV IgM (VCA) is positive and EBNA IgG is negative. What is the diagnosis?

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Correct answer: C — Acute EBV infectious mononucleosis

Positive EBV VCA IgM with negative EBNA IgG confirms acute primary EBV infection (infectious mononucleosis). Monospot (heterophile antibody test) is negative in up to 25% of adults with acute EBV and up to 50% of children. EBNA IgG appears 4–6 weeks after acute infection and remains positive lifelong. Management is supportive. Amoxicillin/ampicillin should be avoided (causes a drug rash in ~90% of EBV patients). Contact sports should be avoided for 3–4 weeks due to splenic rupture risk.

Reference: eTG – 2025 – Antibiotic Guidelines