20-year-male presents with fever, fatigue, posterior cervical lymphadenopathy, palatal petechiae, and splenomegaly. Peripheral smear shows atypical lymphocytes and the heterophile antibody is positive. The likely diagnosis is

The Epstein-Barr virus is the cause of heterophil positive infectious mononucleosisFeatures are fever, sore throat, lymphadenopathy most often affects posterior cervical nodes but may be generalized, splenomegaly and atypical lymphocytosisIt is usually a disease of young adultsRef: Davidson's 20/e p307, Harrison; 18/e p1467-1468