Infectious Mononucleosis

Abstract

1. John Peter, MD* 2. C. George Ray, MD† 1. 2. *Assistant Professor, Department of Pediatrics, Division of Emergency Medicine. 3. 4. †Professor, Department of Pediatrics, Division of Infectious Disease, St. Louis University School of Medicine and Cardinal Glennon Children’s Hospital, St. Louis, MO. 1. The etiologic agent for infectious mononucleosis is Epstein-Barr virus, although a mononucleosis-like syndrome can be caused by other viral agents, most notably cytomegalovirus. 2. The classic physical findings of infectious mononucleosis include fever, lymphadenopathy, pharyngitis, and splenomegaly. 3. Although the presence of heterophil antibodies is considered diagnostic of infectious mononucleosis, children younger than 4 years of age develop an antibody response less than 20% of the time. 4. The primary route of transmission for infectious mononucleosis is saliva; it rarely is spread via aerosol or fomites. 5. Treatment for infectious mononucleosis is generally supportive, with glucocorticoids indicated only for patients exhibiting evidence of airway obstruction. Infectious mononucleosis (IM) was first described in the Russian medical literature in 1885. Epstein-Barr virus (EBV), the viral agent responsible for IM, is a ubiquitous herpes-virus first described by Epstein, Achong, and Barr in continuous cell lines derived from African Burkitt lymphoma tissues. The Henles first observed development of antibodies to EBV in a patient who had acute IM. Subsequent serologic surveys in 1967 confirmed EBV as the major cause of IM. EBV preferentially infects B lymphocytes and is transmitted primarily in saliva or, less commonly, by blood transfusion. It is not likely to be transmitted by aerosol or fomites. After an incubation period of 2 to 7 weeks following exposure, as many as 20% of the circulating B lymphocytes of adolescents or young adults developing IM are infected, although the number usually is closer to 1%. There is a subsequent increase in suppressor T lymphocytes during the acute phase of the infection, which produces a low or“ inverted” T4/T8 (helper/ suppressor) lymphocytic ratio. EBV is shed from the oropharynx for up to 18 months following the primary infection and is shed intermittently in 15% to 25% of healthy EBV-seropositive individuals for years. Immunosuppressed individuals shed the virus more …