Infectious mononucleosis

Infectious mononucleosis is characterised by the classic triad of fever, pharyngitis, and lymphadenopathy, along with atypical lymphocytosis. It is often subclinical in young children.

Caused by infection with Epstein-Barr virus (EBV) in 80% to 90% of cases. Positive heterophile antibody test and serological test for antibodies against EBV are usually diagnostic.

Rare but potentially life-threatening complications include severe upper airway obstruction, splenic rupture, fulminant hepatitis, encephalitis, severe thrombocytopaenia, and haemolytic anaemia.

Treatment is usually symptomatic.

Infectious mononucleosis (IM), also known as glandular fever, is a clinical syndrome most commonly caused by Epstein-Barr virus (EBV) infection in 80% to 90% of cases.[1]Lajo A, Borque C, Del Castillo F, et al. Mononucleosis caused by Epstein-Barr virus and cytomegalovirus in children: a comparative study of 124 cases. Pediatr Infect Dis J. 1994 Jan;13(1):56-60. http://www.ncbi.nlm.nih.gov/pubmed/8170733?tool=bestpractice.com [2]Gershburg E, Pagano JS. Epstein-Barr virus infections: prospects for treatment. J Antimicrob Chemother. 2005 Aug;56(2):277-81. http://jac.oxfordjournals.org/cgi/content/full/56/2/277 http://www.ncbi.nlm.nih.gov/pubmed/16006448?tool=bestpractice.com Other causes are much less common. The diagnosis 'infectious mononucleosis' is primarily used when the syndrome is caused by EBV; 'mononucleosis syndrome' should be used when the syndrome is caused by a non-EBV aetiology. This topic focuses on IM caused by EBV.

IM typically manifests in adolescents and young adults as a febrile illness with sore throat and enlarged lymph nodes. Atypical lymphocytosis and a positive heterophile antibodies test are usually observed. The disease is generally mild in children, but more severe in adults. Resolution of the acute illness is usually followed by a lifelong latent infection, with over 90% of the adult population infected worldwide.[3]Cohen JI. Epstein-Barr virus infection. N Engl J Med. 2000 Aug 17;343(7):481-92. http://www.ncbi.nlm.nih.gov/pubmed/10944566?tool=bestpractice.com