TOC  | ID MONO = Infectious Mononucleosis

Robert L. Weston MD
Dambro: Griffith's 5-Minute Clinical Consult, 2002 ed.

The "mono" syndrome is characterized by fatigue, fever, splenomegaly, adenopathy and pharyngitis. Transmission is fecal-oral, often attributed to kissing. Incubation period is 20-50 days.

Mononucleosis is a viral illness caused by the Epstein-Barr virus (EBV) of the herpes family. It causes 90% of the mono-like syndromes. EBV infection causes general involvement of the lymphoreticular system.

Incidence/Prevalence in USA:



o Positive EBV titers (IgG or IgM) (100%) ;o Lymphocytosis (95%) ;o Atypical monocytosis (95%) ;o Elevated liver function tests (80%) ;o Hypergammaglobulinemia (80%) ;o Positive heterophil antibodies (70%) ;o Thrombocytopenia (50%) ;o Elevated bilirubin (40%) ;o Cold agglutinins (30-80%) ;o Monospot test useful as screen

[The IM heteerophil Antibodies are IgM, appear by the 6-10th day of illness.  Highest titers are in the 2-3rd wk.  THe Ab levels may remain detectable as briefly as 1 week, or persist for as long as a year; usual persistence is 4-8 weeks.   THe level of Ab activity is not correlated with the severity of disease or the degree of lymphocytosis.  About 10% of the adult population with IM will not develop heterophil antibodies.  Less than 2% false positives have been reported with Hodgkin disease, lymphoma, acute lymphocytic leukemia, infectious hepatitis, pancreatic carcinoma, CMV, Burkitt lymphoma, rheumatoid arthritis, malaria, & rubella.  - Lexi-Comp Lexi-Diagnostic Medicine 4/2002] 

[Persistence of antibody was judged by serial bleedings up to three years after illness; titers of heterophile antibody by the sheep agglutination and beef hemolysin tests as well as titers of IgM antibody to Epstein-Barr virus returned to normal in two to three months, whereas the horse cell heterophile test remained positive for a year or more in 75%. - J Infect Dis 1975 Nov;132(5):546-54 ]







Contraindications: Aspirin (associated with Reye's syndrome)



o Chronic EBV Infections (chronic fatigue syndrome- very controversial) ;o Splenic rupture (rare, 0.1-0.5% of patients with proven mononucleosis) ;o Hemolytic anemia (mild) ;o Thrombocytopenic purpura ;o Coagulopathy ;o Aplastic anemia ;o Hemolytic-uremic syndrome ;o Seizures ;o Cerebellar syndrome ;o Nerve palsies ;o Meningoencephalitis ;o Optic neuritis ;o Reye's syndrome ;o Coma ;o Transverse myelitis ;o Guillain-Barré syndrome ;o Psychosis ;o Pericarditis ;o Myocarditis ;o ECG changes ;o Airway obstruction ;o Pneumonitis ;o Pleural effusion ;o Pulmonary hemorrhage ;o Hepatitis/liver necrosis ;o Malabsorption ;o Dermatitis ;o Urticaria ;o Erythema multiforme ;o Glomerulonephritis ;o Nephrotic syndrome ;o Mild hematuria/proteinuria ;o Conjunctivitis ;o Episcleritis ;o Uveitis ;o ß-hemolytic streptococcal infections ;o Staphylococcal infection ;o Mycoplasma infection ;o Bullous myringitis ;o Orchitis ;o Parotitis ;o Monoarticular arthritis ;o Jaundice


o Fever subsides in about 10 days ;o Adenopathy and splenomegaly subside in about 4 weeks ;o Children should be able to return to school when signs of infection have decreased, appetite returns, and alertness, strength, and sense of well-being allow. ;o Death is uncommon (splenic rupture, blood dyscrasias, hypersplenism, or encephalitis) ;o Potential role in some malignancies, especially in context of immune suppression .