Infectious mononucleosis is a clinical entity characterized by
pharyngitis, cervical lymph node enlargement,
fatigue and
fever, which results most often from a primary Epstein-Barr virus (
EBV) infection. EBV, a lymphocrytovirus and a member of the γ-herpesvirus family, infects at least 90% of the population worldwide, the majority of whom have no recognizable illness. The virus is spread by intimate oral contact among adolescents, but how preadolescents acquire the virus is not known. During the incubation period of approximately 6 weeks, viral replication first occurs in the oropharynx followed by
viremia as early
as 2 weeks before onset of illness. The acute illness is marked by high viral loads in both the oral cavity and blood accompanied by the production of
immunoglobulin M antibodies against EBV viral capsid
antigen and an extraordinary expansion of CD8(+) T lymphocytes directed against EBV-infected B cells. During
convalescence, CD8(+) T cells return to normal levels and
antibodies develop against EBV nuclear antigen-1. A typical clinical picture in an adolescent or young adult with a positive heterophile test is usually sufficient to make the diagnosis of
infectious mononucleosis, but
heterophile antibodies are not specific and do not develop in some patients especially young children. EBV-specific antibody profiles are the best choice for staging
EBV infection. In addition to causing acute illness, long-term consequences are linked to
infectious mononucleosis, especially
Hodgkin lymphoma and
multiple sclerosis. There is no licensed
vaccine for prevention and no specific approved treatment. Future research goals are development of an EBV
vaccine, understanding the risk factors for severity of the acute illness and likelihood of developing
cancer or
autoimmune diseases, and discovering anti-EBV drugs to treat
infectious mononucleosis and other EBV-spurred diseases.