ABSTRACT
The Epstein-Barr virus (EBV) is a ubiquitous pathogen. It causes infection throughout the world in all populations. In general, the younger the age at which the primary infection occurs, the more likely it is to be mild and clinically insignificant. In many developing countries, almost all infections caused by EBV occur early in life and are either unaccompanied by symptoms or associated with only minor, nonspecific illnesses, such as low-grade fever or sore throat. In the more industrialized countries of the world in which substantial portions of the population enjoy higher socioeconomic status, primary infection is often delayed until adolescence or early adulthood. Among older adolescents and adults, significant numbers of individuals become ill during infection, which often takes the form of classic, heterophile antibody-positive infectious mononucleosis (IM).
