Infectious mononucleosis

• Infectious mononucleosis:

  • Also called glandular fever or mono
  • Most commonly caused by the Epstein-Barr virus
  • Characterised by the triad of: fever, pharyngitis and cervical lymphadenopathy
  • Mainly spread through contact with salvia, usually from asymptomatic carrier through kissing, sharing food and drink utensils
  • Can also be spread through sexual contact (blood and semen), blood transfusions, organ transplantation, and intrauterine transmission
• Incubation period:

  • Around 4-7 weeks
  • Disease is contagious during the incubation period and while symptoms are present
  • Some people can be contagious for as long as 18 months after infection
  • Not everyone infected with EBV will get glandular fever - glandular fever is most likely to occur in those who are infected in their teenage years compared to those infected at a younger or older age
• Demographics:

  • Most common in people aged 15-24
  • Following the acute illness, EBV becomes latent in the body - over 90% of the adult population worldwide have been infected, but not everyone will have had glandular fever
  • In older people (>40) glandular fever is rare and can present atypically e.g. no sore throat or lymphadenopathy, sometimes just an unexplained fever or complications e.g. jaundice
  • In young children infection is usually asymptomatic, and if they do have symptoms it's usually indistinguishable from other childhood viral illnesses
• EBV (also known as human herpes virus 4) is a double-stranded DNA virus from the herpes family. 
• Symptoms:

  • Prodromal - general malaise, fatigue, myalgia, chills, retro-orbital headache
  • Fever
  • Sore throat - usually severe
  • Non-specific rash
• Examination findings:

  • Lymphadenopathy - bilateral posterior cervical lymphadenopathy is typical but other lymph nodes can be involved e.g. other head and neck lymph nodes, axilla, inguinal. Usually mildly tender and mobile
  • Enlarged tonsils with whitewash exudate
  • Palatal petechiae
  • Organomegaly - splenomegaly and sometimes hepatomegaly
• Investigations for children >12 and immunocompetent adults:

  • FBC - expect to see lymphocyte count >50% total WCC
  • Monospot test - in second week of illness to give time for antibody production
  • Consider other bloods if concerned about complications e.g. LFTs
• Investigations for children <12 and immunocompromised patients:

  • EBV viral serology - can be performed after 7 days of illness, has a higher sensitivity and specificity than monospot test
  • Consider other bloods if concerned about complications e.g. LFTs
• Monospot test:

  • Detects presence of a type of antibody produced in response to infectious mononucleosis - heterophile antibodies
  • High specificity rate - although heterophile antibodies can also be produced in other conditions e.g. HIV
  • Lower sensitivity rate - even less in young children (have high false negative rate)
  • If monospot test is negative the options are:

  1. Repeat in 5-7 days, if negative consider different cause e.g. CMV, HIV
  2. EBV viral serology (if need rapid diagnosis)
• Infectious mononucleosis is primarily used to describe causes caused by EBV infection. Mononucleosis syndrome should be used when the illness is due to a non-EBV aetiology:

  • HIV
  • CMV
  • Other human herpes viruses
  • Toxoplasma gondii
  • Streptococcus pyogenes
• Management:

  • Usually self-limiting and last 2-4 weeks - reassure patient
  • Advise patient to:

  1. Limit spread by avoiding kissing and sharing utensils
  2. Avoid contact sport and heavy lifting for first month of illness to reduce risk of splenic rupture
  3. Return to normal activities as soon as able - exclusion from work/school not necessary

  • Simple analgesia
  • Safety net
  • Consider admission if stridor, significant dehydration or serious complications
• Penicillin-induced rash:

  • If Glandular fever is misdiagnosed as bacterial sore throat and treated with antibiotics like amoxicillin or cephalosporins (beta-lactam) this can result in an extensive itchy maculopapular rash
  • The rash usually resolves within a week of stopping the antibiotics.
  • The pathophysiology of the rash is not known - suspected to represent an EBV-induced hypersensitivity reaction
• Acute complications:

  • Airway obstruction - due to tonsillar oedema or peritonsillar abscess
  • Cardiac - pericarditis, myocarditis and arrhythmias
  • Neurological - encephalitis, aseptic meningitis, GBS and optic neuritis
  • Haematological - thrombocytopenia (common), autoimmune haemolytic anaemia
  • Liver - abnormal LFTs, hepatitis
  • Splenic rupture - avoid contact sports but majority of cases are spontaneous
  • Renal - interstitial nephritis
  • Deep neck space infections
• Long-term complications:

  • Chronic fatigue - majority recover within 2 years
  • Lymphoproliferative cancers - particularly Hodgkin's lymphoma and Burkitt lymphoma
  • Chronic active EBV infection
  • Multiple sclerosis