Infectious mononucleosis is an acute infectious disease of children, adolescents, and young adults. It is caused by the Epstein–Barr virus (EB virus) and is followed by lifelong immunity.

Distribution and Incidence

On the basis of the populations investigated, it would seem that infectious mononucleosis occurs worldwide but attacks only those persons who have had no EBV antibodies. The virus replicates in the salivary glands, is present in the oropharyngeal secretions of patients ill with the disease, and continues to be shed for months following convalescence. As a lifelong inhabitant of the lymphoid tissues, it is excreted intermittently into the oropharynx.

In the underdeveloped countries it is a disease of childhood, and, since it spreads by contact with oral secretions, crowding and unhygienic surroundings favor its ready transmission. In more developed countries, it strikes especially those of the 15- to 25-year age group and is recognized clinically as infectious mononucleosis. In the United States, on college campuses, the disease is commonly known as the “kissing disease.”

Children of low socioeconomic state almost universally show antibodies to the virus. (In Ghana, 84 percent of infants have acquired antibodies by age 21 months.) In a worldwide prospective study of 5,000 children and young adults without EB virus antibodies, 29 percent developed antibodies within a period of 4 to 8 years. Among susceptible college students the annual incidence of the disease is about 15 percent.