Infectious mononucleosis (IM) & Epstein-Barr Virus (EBV)

Cause of infectious mononucleosis

  • Commonest cause – EBV.

  • Other causes of mononucleosis-like syndrome – CMV, HIV (during seroconversion), Toxoplasma, Hepatitis virus, Adenovirus etc

Epidemiology of IM

  • Primary EBV infection and infectious mononucleosis are common in children, teenagers and young adults.

  • 95% of healthy individuals are infected with EBV.

  • In children, infection is usually mild or even asymptomatic.

  • Symptomatic disease is common in teenagers and young adults (15-24 years).

  • In adults, the infection is less common, but often severe.

Transmission

  • It is transmitted via body fluid. Saliva is the commonest mode.

  • Once infected, an individual can shed the virus in the saliva for approx. 6 months, and intermittently, lifelong.

  • It is called kissing disease but can be transmitted via less intimate contact than this.

  • Other modes are – sexual contact and breastfeeding.

Signs and symptoms

  • Triad of – Fever, tonsillar pharyngitis and lymphadenopathy.

  • Other common features are – fatigue, splenomegaly (up to 60% cases) and low mood.

  • You may also find – hepatomegaly, rash, headache and body ache.

Complications

  • Usually self-limiting disease.

  • Neurological complications – meningoencephalitis, transverse myelitis, optic neuritis, Cranial nerve palsy, Guillain–Barré syndrome.

  • Haematological complications – aplastic anaemia, thrombocytopenia and related complications.

  • Other complications – Splenic rupture, airway obstruction, myocarditis, hepatitis, and renal failure.

Diagnosis

  • Typical clinical features

  • Haematology – increased white cell count, atypical lymphocytes, anaemia, thrombocytopenia.

  • Heterophile antibody test – e.g. Paul Bunnel test or, monospot test

  • EBV serology

  • EBV PCR

Differential diagnosis

  • Streptococcal sore throat (Group A Streptococcus)

  • Mononucleosis like syndrome – CMV, HIV seroconversion, Toxoplasma infection, Viral hepatitis, Adenovirus etc.

  • Leukaemia

  • Drugs – phenytoin, carbamazepine

Treatment

  • Usually, self-limiting.

  • Supporting treatment – nutrition, hydration

  • Paracetamol, NSAIDs

  • Steroids and acyclovir – selected cases

  • Avoid sports for 4 weeks (risk of splenic rupture).

If you are interested to know what is a heterophile antibody see this video.

  • Heterophile antibody test should not be done in children <4 years or immunocompromised patients (risk of false-negative result)

False-positive results can be seen in – rheumatoid disease, SLE, leukaemia, lymphoma, infections including malaria, HIV, CMV, rubella, viral hepatitis, tularaemia etc.

90% of patients are expected to me positive heterophil antibodies by 3wks, and they disappear at approximately 3 months.

Atypical lymphocytes can also be seen in CMV, HIV, HHV6, rubella, mumps, viral hepatitis, toxoplasmosis, typhus, lead poisoning etc.