Infectious mononucleosis

Question 1

What is infectious mononucleosis?

Answer 1

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.

Question 2

Classic triad of glandular fever?

Answer 2

Theclassic triad of sore throat, pyrexia and lymphadenopathyis 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

Question 3

other features of infectious mononucleosis?

Answer 3

• 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 anaemiasecondary tocold agglutins (IgM)
• a maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis

Question 4

When do symptoms typically resolve?

Answer 4

2-4 weeks

Question 5

Diagnosis of infectious mononucleosis?

Answer 5

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.