Infectious mononucleosis

Overview

• Definition: Clinical syndrome typically caused by the **Epstein-Barr virus (EBV)**, characterised by fever, pharyngitis, lymphadenopathy, and fatigue.
• Often referred to as ‘mono’ or ‘glandular fever’.
• Most commonly affects adolescents and young adults.

Etiology

• Primarily due to **EBV**, a member of the herpesvirus family.
• Transmission typically through saliva (“kissing disease”).
• Less common causes include cytomegalovirus (CMV) and other agents.

Clinical Features

• Triad: Fever, pharyngitis (sore throat), and cervical lymphadenopathy.
• Fatigue and malaise, which can persist for weeks to months.
• Possible splenomegaly and hepatomegaly.
• Rash, especially if given ampicillin or amoxicillin.

Investigations

• Monospot test (heterophile antibody test): Diagnostic in majority but not 100% specific or sensitive.
• EBV-specific serology for uncertain cases.
• Full blood count: Atypical lymphocytes, lymphocytosis.
• Liver function tests: Raised alanine transaminase (ALT) and aspartate transaminase (AST).

Management

• Primarily supportive care:
  • Rest, hydration, analgesia (paracetamol or ibuprofen).
• Avoid contact sports due to risk of splenic rupture.
• Avoid ampicillin or amoxicillin to prevent rash.
• Corticosteroids may be considered in severe cases, airway obstruction, or haemolytic anaemia, but routine use is controversial.

Complications

• Splenic rupture (though rare).
• Neurological complications: Meningitis, encephalitis, Guillain-Barré syndrome.
• Hepatitis, jaundice.
• Secondary bacterial pharyngitis or tonsillitis.

Key Points

• EBV is the most common cause of infectious mononucleosis.
• Diagnosis primarily clinical but supported by Monospot and serology.
• Management is mainly supportive; be cautious of splenic rupture in physical activity.