– An acute viral infectious disease characterized by fatigue, fever, pharyngitis, and lymphadenopathy.

Causes and Incidence

Mononucleosis is caused by the Epstein-Barr virus (EBV) and transmitted via prolonged contact with infected saliva or through blood transfusion. After the primary infection the virus remains in the host for life and is periodically shed in nasal secretions. At any given time, 15% to 20% of the adult population are active carriers. Mononucleosis is common in the United States, Canada, and Europe, particularly among adolescents and young adults.

Disease Process

EBV invades the host and incubates for 4 to 6 weeks. It then replicates in the nasopharynx and moves to the lymphatic system, where it infects B lymphocytes and stimulates the secretion of an antigen. T lymphocytes proliferate in response to the antigen, producing a generalized lymph node hyperplasia.


Profound fatigue; a fever that peaks in the late afternoon at 38.3o to 40.6o C (101o to 105o F); severely painful and exudative pharyngitis; and symmetric lymphadenopathy are the hallmark signs. Splenomegaly is usually present in the second or third week. Mild hepatomegaly may also be present. A maculopapular rash, palatal petechiae, and periorbital edema are less common signs.

Potential Complications

The prognosis is excellent; complications are rare but include splenic rupture, anemia, Guillain-Barre syndrome, meningitis, and encephalitis.

Diagnostic Tests

The presence of clinical manifestations plus a differential WBC showing lymphocytes and monocytes over 50%; a heterophil agglutination antibody test with an antibody titer greater than 1:40; and an EBV-IgM test with antibodies over 1:80 are all suggestive of mononucleosis.


Removal of the spleen in cases of rupture.

Nonaspirin analgesics and antipyretics; steroids for treating impending airway obstruction.

Bed rest during the acute phase; saline throat gargles; adequate hydration; avoidance of heavy lifting and contact sports for 2 months after recovery to prevent injury to spleen.