Mononucleosis

EBV is transmitted by salivary secretions, usually from an asymptomatic person shedding the virus. Transmission often occurs from adults to infants or among young adults by transfer of saliva during kissing. The virus infects the epithelium of the oropharynx and salivary glands and is shed from these cells. Infectious mononucleosis is characterized by fever, sore throat, lymphadenopathy, and atypical lymphocytosis. EBV is also associated with several human tumors, including nasopharyngeal carcinoma, Burkitt's lymphoma, Hodgkin's disease, and in patients with immunodeficiencies (including AIDS),and B-cell lymphoma.(1) The virus was originally discovered in association with Burkitt's lymphoma cells, and is a member of the family Herpesviridae.

Epstein-Barr virus infections occur worldwide. In fact, by adulthood, over 90 percent of individuals have been infected and have antibodies to the virus. Infections occur with greatest frequency in early childhood, with another peak during late adolescence. In areas with lower standards of hygiene, such as those observed in lower socioeconomic classes and developing nations, the infection is seen mostly in young childhood, while in areas of higher standards of hygiene, the infection occurs primarily in young adulthood. Most EBV infections in infants and young children are either asymptomatic, or present as a mild pharyngitis with or without tonsillitis. In contrast, when seen in late adolescence, it very frequently (up to 75 percent) presents as infectious mononucleosis.

With mononucleosis, a three to five day prodrome consisting of a sore throat, fever, and asthenia is observed after a 30-50 day incubation period. Physical examination usually reveals pharyngitis with tonsillar exudates, palatal petichiae, and posterior cervical adenopathies. In 50 to 75 percent of cases, splenomegaly can be palpated after two weeks of active disease. A macular erythematous rash is present in 10 percent of cases, but increases to 50 percent in cases where ampicillin has been prescribed. Finally, jaundice can be documented in 5 percent of patients, whereas liver transaminases (aspartane transaminase (AST), and alanine transaminase (ALT)) are reported in 40 percent of cases.(2)

In some cases, the fatigue, myalgia, and malaise may be present for one to two weeks prior to onset of fever, sore throat, and lymphadenopathy. Most patients have symptoms for two to four weeks, but malaise and difficulty concentrating can persist for months.

When occurring in the elderly, mostly nonspecific symptoms are noted, including prolonged fever, malaise, myalgia, and fatigue; in contrast, pharyngitis, lymphadenopathy, splenomegaly, and atypical lymphocytes are rarely seen. Complications are uncommon, and most cases of infectious mononucleosis are self-limiting. Deaths are very rare and are most often due to central nervous system complications, splenic rupture, upper airway obstruction, or bacterial superinfection.