The many faces of Epstein-Barr virus.

Epstein-Barr virus (EBV) persists for life in a person who has been infected. Investigators are uncertain what this means to the host, particularly an immunocompromised one. EBV is the most common cause of infectious mononucleosis, but the diagnosis must be based on clinical, hematologic, and serologic criteria because other agents are the cause in about 10% of cases. EBV is the first virus to be associated with a neoplasm--Burkitt's lymphoma. This childhood malignancy is relatively common in central Africa, and EBV is a cofactor in its development, although direct evidence for a causal relationship has not been found. In southern China, nasopharyngeal carcinoma is an important health problem in adults in areas where the infection rate of EBV in childhood is high. Rare cases of primary EBV infection that evolved into uncontrolled lymphoproliferative disease have also been reported. EBV's relationship to these diverse diseases, its varying effects on certain individuals and in certain geographic locations, and the testing of a vaccine against the virus are areas of ongoing study.