Infectious Mononucleosis

Question 1

Definition

Answer 1

· Clinical syndrome caused by primary EBV infection

o AKA glandular fever

Question 2

Aetiology

Answer 2

· EBV is a gamma-Herpes virus (dsDNA)
· It is found in the pharyngeal secretions of infected individuals and is transmitted by close contact (e.g. kissing, sharing eating utensils)

· EBV infection of the epithelial cells of the oropharynx leads to B cell infection
· The infected B cells disseminate EBV across the body leading to a humoral and cellular immune response

· Atypical lymphocytes in the peripheral blood are a classic feature of infectious mononucleosis

· EBV remains latent in lymphocytes

· Reactivation may occur following stress or immunosuppression

Question 3

Epidemiology

Answer 3

· COMMON

· TWO age peaks:
o 1-6 yrs
o 14-20 yrs

Question 4

Presenting symptoms

Answer 4

· Incubation period: 4-8 weeks

· Abrupt onset of symptoms:
o Sore throat
o Fever
o Fatigue
o Headache
o Malaise
o Anorexia
o Sweating
o Abdominal pain

Question 5

Signs on physical examination

Answer 5

· PYREXIA
· Oedema and erythema of the pharynx
· White/creamy exudate on the tonsils
· Palatal petechiae
· Cervical/generalised lymphadenopathy
· Splenomegaly
· Hepatomegaly
· Jaundice (5-10%)
· Widespread maculopapular rash (in patients who have received ampicillin)

Question 6

Investigations (bloods)

Answer 6

· Bloods
o FBC - leucocytosis
o LFTs - high AST/ALT

· Blood Film - lymphocytosis with atypical lymphocytes

Question 7

Investigations (other)

Answer 7

· Heterophil Antibody Test (aka Monospot Test, Paul Bunnell Test)
o Based on EBV antigens being similar to antigens on RBCs of many animals but NOT humans
o Mixing blood of an EBV-positive human with animal blood will make the animal’s red cells aggregate and precipitate out of solution
o May give false-negatives in the early stages of infection before antibodies are generated

· Throat swabs - exclude streptococcal tonsillitis

· IgM or IgG to EBV viral capsid antigen

· IgG against Epstein-Barr nuclear antigen (EBNA)

Question 8

Management plan

Answer 8

· Bed rest

· Paracetamol and NSAIDs - helps with fever, malaise

· Corticosteroids in SEVERE cases

· IMPORTANT: do NOT give AMPICILLIN or AMOXICILLIN if infectious mononucleosis is suspected - nearly 100% of patients with glandular fever develop a maculopapular rash

· Advice - avoid contact sports for 2 weeks (because of risk of rupturing your spleen)

Question 9

Possible complications

Answer 9

· Lethargy for several months

· Respiratory - airway obstruction from oedematous pharynx, secondary bacterial throat infection, pneumonitis

· Haematological - haemolytic or aplastic anaemia, thrombocytopenia

· GI/Renal - splenic rupture, fulminant hepatitis, pancreatitis, mesenteric adenitis, renal failure

· CNS - Guillain-Barre syndrome, encephalitis, viral meningitis

· EBV-associated malignancy - Burkitt’s lymphoma (in sub-Saharan Africa), nasopharyngeal cancer, Hodgkin’s lymphoma

Question 10

Prognosis

Answer 10

· Most make uncomplicated recovery (within 3 weeks)

· Immunodeficiency and death are VERY RARE