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Infectious mononucleosis (EBV)
EBV mononucleosis presents with fever, pharyngitis, posterior neck nodes and an enlarged spleen in an adolescent or young adult; it is diagnosed with the heterophile antibody test (Monospot) or EBV VCA IgM, treated supportively, and contact sport is put off for 3–4 weeks or longer since the swollen spleen may rupture.
Why it matters in the exam
The question presents a student with fever, a sore throat with exudate on the tonsils, posterior neck nodes, severe fatigue and an enlarged spleen, sometimes with mildly raised transaminases and "atypical" lymphocytes on the film. A standard distractor: the patient was given amoxicillin "for a sore throat" and developed a rash — this is typical of EBV and not true allergy. The Monospot can be negative in the first week and in young children, and then specific EBV antibodies (VCA IgM) are checked.
Treatment is supportive: fluids, analgesia and rest; steroids are reserved for airway obstruction from nodes and tonsils, severe haemolysis or severe thrombocytopenia, and antivirals have no role. Contact sport is forbidden for at least 3–4 weeks from the start of the illness. Complications: splenic rupture (left upper abdominal pain and shock), airway obstruction, "cold" haemolytic anaemia, thrombocytopenia and hepatitis. If the Monospot is negative with a similar picture — CMV, toxoplasmosis and acute HIV are the differential, so HIV is tested in those at risk. Fatigue can last weeks or even months after the fever has gone, and the patient should be told this in advance; spread is through saliva ("the kissing disease"), and no special isolation is needed beyond avoiding shared cups and kissing during the illness.
Key points
- Fever, pharyngitis, posterior nodes, enlarged spleen, atypical lymphocytes.
- Monospot; if negative — EBV VCA IgM.
- Supportive treatment; steroids only for complications.
- No contact sport for at least 3–4 weeks.
- Rash with amoxicillin; differential: CMV and acute HIV.
Summary table
| Topic | Finding | Action | Exam note |
|---|---|---|---|
| Clinical picture | Fever, pharyngitis, posterior neck nodes, enlarged spleen | Monospot and film (atypical lymphocytes) | Adolescents and young adults |
| Negative Monospot | First week or young child | EBV VCA IgM | Think of CMV and acute HIV too |
| Rash after amoxicillin | Maculopapular rash | Not true allergy | A diagnostic clue |
| Treatment | Most patients | Supportive: fluids, analgesia | No antivirals |
| Steroids | Severe airway obstruction, haemolysis or thrombocytopenia | Short prednisone | Not routine |
| Sport | Enlarged spleen | Avoid contact sport for at least 3–4 weeks | Risk of splenic rupture |
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Sources
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Epstein-Barr Virus Infections, Including Infectious Mononucleosis
- CDC Clinical Overview: Epstein-Barr Virus and Infectious Mononucleosis, 2024 — Diagnosis and return to sport
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.