Makindo Medical Notes

For individual viral causes, please see their dedicated sections. Infectious mononucleosis is a classic “exam syndrome” — always think EBV first, but don’t forget the mimics.

📖 About Infectious Mononucleosis

• A clinical syndrome usually caused by Epstein-Barr Virus (EBV), a gamma-herpesvirus that infects B lymphocytes.
• Other agents (e.g. CMV, HIV, HHV-6, toxoplasmosis) can cause an “EBV-like” illness and should be considered in differential diagnoses.
• EBV is linked to oncogenesis (Hodgkin’s lymphoma, Burkitt’s lymphoma, nasopharyngeal carcinoma).

📊 Epidemiology

• Most cases present in teenagers or young adults (“kissing disease”).
• In developing countries, infection often occurs in early childhood, where it tends to be mild or asymptomatic.

🦠 Spread

• Mainly transmitted through saliva (“kissing”, sharing utensils, droplets).
• Infects B lymphocytes via the CD21 receptor, leading to a marked T-cell response responsible for many symptoms.

🧾 Causes of Mononucleosis-like Illness

• EBV — most common.
• CMV — especially in adults with negative EBV tests.
• HHV-6/7 — less common.
• HIV seroconversion — important to rule out in high-risk cases.
• Toxoplasmosis — may mimic EBV but usually with exposure history (e.g. undercooked meat, cat litter).

🩺 Clinical Presentation

• Classic triad: fever, sore throat, and posterior cervical lymphadenopathy.
• Splenomegaly (risk of rupture if trauma occurs) and hepatomegaly may be present.
• Ampicillin Rash: Use of ampicillin/amoxicillin in EBV infection produces a widespread maculopapular rash.
• Other features: profound fatigue, malaise, palatal petechiae.
• Severe manifestations: laryngeal oedema, cranial nerve palsies, meningoencephalitis, haemolytic anaemia, glomerulonephritis, myocarditis, or pneumonitis.

📉 Rare Long-Term Complications

• Hodgkin’s lymphoma
• Endemic Burkitt’s lymphoma (esp. Africa, linked with malaria co-infection)
• Nasopharyngeal carcinoma (esp. in Southeast Asia)

🔬 Investigations

• FBC: Lymphocytosis with >10% atypical lymphocytes is highly suggestive.
• Monospot (heterophile antibody) test: Quick bedside test but may be negative in first week of illness.
• EBV serology: IgM anti-VCA confirms acute EBV infection.
• Consider HIV testing if presentation is atypical or risk factors are present.

💊 Management

• Supportive: fluids, rest, paracetamol/NSAIDs, warm saline gargles.
• Steroids: Reserved for airway obstruction due to tonsillar hypertrophy or severe systemic complications.
• Avoid antibiotics unless bacterial superinfection suspected. Avoid ampicillin/amoxicillin (rash risk).
• Avoid contact sports for at least 4 weeks (or until splenomegaly resolves on exam/USS) due to risk of splenic rupture.

📝 Exam Pearls

• Teenager with sore throat, lymphadenopathy, hepatosplenomegaly, and rash after amoxicillin = EBV.
• Posterior cervical nodes are more typical of EBV, anterior cervical of strep throat.
• Always exclude HIV in mononucleosis-like illness with risk factors.