Infectious mononucleosis (glandular fever)
Overview
Infectious mononucleosis (IM, glandular fever) is a clinical syndrome usually characterised by the triad of fever, sore throat (often exudative tonsillitis) and lymphadenopathy, commonly accompanied by splenomegaly and mild hepatitis.
Epstein-Barr virus (EBV) causes most cases; other causes of a mono‑like illness include cytomegalovirus (CMV), acute HIV, toxoplasmosis and adenovirus. Disease is usually self‑limited but patients may present to the ED with severe throat swelling, dehydration, airway compromise or complications such as splenic rupture.
Epidemiology and transmission
- EBV causes approximately 90% of classic glandular fever; symptomatic disease most commonly affects adolescents and young adults (peak 15-24 years).
- Most infections in childhood are mild or asymptomatic and more than 95% of adults worldwide have serological evidence of prior EBV infection.
- Incubation period is typically 4-8 weeks.
- Transmission is via infected saliva (kissing, sharing utensils) and viral shedding may persist after clinical recovery.
Pathophysiology (concise)
- EBV infects oropharyngeal epithelial cells and B lymphocytes.
- The characteristic atypical lymphocytes on blood film are reactive CD8+ T cells responding to infected B cells.
- The immune response explains lymphadenopathy, systemic symptoms and transaminitis.