Epstein-Barr virus, cytomegalovirus, and infectious mononucleosis.

Infectious mononucleosis (IM) is a clinical syndrome that is common in adolescents and young adults and is characterized by fever, lymphadenopathy, pharyngitis, and fatigue. IM is most commonly associated with Epstein-Barr virus (EBV) infection in which case laboratory findings include a lymphocytosis with an elevated number of atypical lymphocytes seen on peripheral smear and a heterophile or EBV-specific antibody response. Approximately 10% of those with IM will not be acutely infected with EBV. Many of these individuals will have their symptoms attributed to cytomegalovirus (CMV) infection. This chapter reviews the history, diagnosis, clinical management, and potential complications of both EBV- and CMV-associated IM in adolescents and young adults.