Infectious mononucleosis

Infectious mononucleosis (glandular fever) is caused by the Epstein-Barr virus (EBV, also known as human herpesvirus 4, HHV-4) in 90% of cases. Less frequent causes include cytomegalovirus and HHV-6. It is most common in adolescents and young adults.

The classic triad of sore throat, pyrexia and lymphadenopathy is seen in around 98% of patients:

• sore throat
• lymphadenopathy: may be present in the anterior and posterior triangles of the neck, in contrast to tonsillitis which typically only results in the upper anterior cervical chain being enlarged
• pyrexia

Other features include:

• malaise, anorexia, headache
• palatal petechiae
• splenomegaly - occurs in around 50% of patients and may rarely predispose to splenic rupture
• hepatitis, transient rise in ALT
• lymphocytosis: presence of 50% lymphocytes with at least 10% atypical lymphocytes
• haemolytic anaemia secondary to cold agglutins (IgM)
• a maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis

Symptoms typically resolve after 2-4 weeks.

Diagnosis

• heterophil antibody test (Monospot test)
  • NICE guidelines suggest FBC and Monospot in the 2nd week of the illness to confirm a diagnosis of glandular fever.

Management is supportive and includes:

• rest during the early stages, drink plenty of fluid, avoid alcohol
• simple analgesia for any aches or pains