Infectious mononucleosis is an acute infectious disease caused by the Epstein-Barr virus (EBV), a member of the herpes group. It primarily affects young adults and children, although in children it’s usually so mild that it’s commonly overlooked.
Characteristically, infectious mononucleosis produces fever, sore throat, and cervical lymphadenopathy (the hallmarks of the disease), as well as hepatic dysfunction, increased lymphocytes and monocytes, and development and persistence of heterophil antibodies. The prognosis is excellent, and major complications are uncommon.
Apparently, the reservoir of EBV is limited to humans. Infectious mononucleosis probably spreads by the oropharyngeal route because about 80% of patients carry EBV in their throats during the acute infection and for an indefinite period afterward.
It can also be transmitted by blood transfusion and has been reported after cardiac surgery as the “post–pump perfusion” syndrome. Infectious mononucleosis is probably contagious from before symptoms develop until the fever subsides and oropharyngeal lesions disappear.
Infectious mononucleosis is fairly common in the United States, Canada, and Europe, and both sexes are affected equally. Incidence varies seasonally among college students (most common in early spring and early fall) but not among the general population.