Infectious mononucleosis

Question 1

Aetiology of infectious mononucleosis

Answer 1

Epstein-Barr Virus (EBV/HHV-4) in 80-90% of cases
dsDNA virus.
- Transmission is through saliva (“kissing disease”) also transmitted by sexual transmission
- EBV shed virus in saliva for 15 months, incubation period 4-7 weeks
- EBV remains latent lifelong in lymphocytes and reactivation can occur following stress of immunosuppression
- There is persistent low-grade replication, and the virus is shed intermittently into pharyngeal secretions, particularly saliva

• infections: HHV-6, cytomegalovirus, HSV-1, streptococcus pyogenes, Toxoplasma gondii, Francisella tularensis, hep A and B, rubella, enteroviruses.
• Connective tissue disorders
• Malignancies
• Drug reactions

Question 2

Symptoms of infectious mononucleosis

Answer 2

Fever
Sore throat
Neck lumps
Malaise
Rash
- Appears first day of illness
- Can be erythematous, maculopapular or morbilliform

Jaundice
Myalgia

Question 3

Signs of infectious mononucleosis

Answer 3

Pharyngitis (exudative or non-exudative)
Cervical or generalised lymphadenopathy
- Nodes typically tender, non-erythematous, and discrete
- Most prominent over the second week of illness
Splenomegaly
Rash
- Appears first day of illness
- Can be erythematous, maculopapular or morbilliform
Signs of hepatitis

Question 4

Investigations for infectious mononucleosis

Answer 4

FBC: lymphocytosis, anaemia + reticulocytosis (haemolytic anaemia)
Blood film: atypical lymphocytes
Monospot (heterophile antibodies): positive
EBV antibodies: +ve viral capsid antigen (VCA) IGM, VCA IgG, EBV nuclear antigen (EBNA)
LFTs: elevated ALT/AST
PCR: DNA detection

CT/US abdomen: splenomegaly

Question 4

Management for infectious mononucleosis

Answer 4

Supportive
- Paracetamol or buprofen
- Hydration
- Refrain from strenuous physical activity and contact sports (splenomegaly)
- NO aspirin (children - Reye’s syndrome) or Amoxicillin/ampicillin (widespread maculopapular rash)

Upper airway obstruction or haemolytic anaemia → oral corticosteroids

Thombocytopenia → PO prednisolone or IVIg

Question 5

Complications of infectious mononucleosis

Answer 5

Chronic active EBV infection
Neurological complications: encephalitis, aseptic meningitis, facial nerve palsy, transverse myelitis, GBS, optic neuritis, multiple sclerosis
Abdo:
- Splenic rupture
- Hepatitis
- Acute acalculous cholecystitis
- Renal: nephritis, AKI, haemolytic uraemic syndrome, nephropathy
Auto-immune disease e.g. SLE, RA
Malignancy
Chronic fatigue
Upper airway obstruction
Cardio: pericarditis, myocarditis
Haem: thrombocytopenia, haemolytic anaemia, Haemophagocytic lymphohistiocytosis (HLH)

Question 6

Prognosis for infectious mononucleosis

Answer 6

Prognosis is very good in healthy people
In most, self limiting and lasts 2-4 weeks EBV infection leads to lifelong latent carrier state
Death is caused by airway obstruction, splenic rupture, neuro complications, haemorrhage, or secondary infection