It is commonly known as the “kissing disease”, “glandular fever” or “mono”. ****

Aetiology:

• Infectious mononucleosis (IM) is a condition caused by infection with the Epstein Barr virus (EBV) in 90% of cases. ****
• Less frequent causes include cytomegalovirus and HHV-6. It is most common in adolescents and young adults.

Pathophysiology

• This virus is found in the saliva of infected individuals. Infection may be spread by kissing or by sharing cups, toothbrushes and other equipment that transmits saliva.
• Most people are infected with EBV as children, when it causes very few symptoms. When infection occurs in teenagers or young adults, it causes more severe symptoms. It is the symptomatic infection with EBV that is called infectious mononucleosis.

PC:

Classic triad (98% of patients): sore throat, pyrexia, lymphadenopathy

Other features:

• malaise, anorexia, headache
• palatal petechiae
• splenomegaly - occurs in around 50% of patients and may rarely predispose to splenic rupture
• a maculopapular, pruritic rash develops in around 99% of patients who take ampicillin/amoxicillin whilst they have infectious mononucleosis

EXAM TIP: Look out for the exam question that describes an adolescent with a sore throat, who develops an itchy rash after taking amoxicillin. Mononucleosis causes an intensely itchy maculopapular rash in response to amoxicillin or cefalosporins.

Investigations