Infectious Mononucleosis

Infectious Mononucleosis

Seroepidemiologic surveys indicate that over 95% of adults worldwide are infected with EBV. In industrialized countries and higher socioeconomic groups, half the population has primary EBV infection between 1 and 5 years of age, with another large percentage becoming infected in the second decade. Because economic and sanitary conditions have improved over past decades, EBV infection in early childhood has become less common, and more children are susceptible as they reach adolescence.

What is the classic triad of presenting signs of infectious mononucleosis?
Pharyngitis (usually subacute in onset), fever, and lymphadenopathy constitute the classic triad of presenting signs of infectious mononucleosis. Sore throat and malaise or fatigue are the most common presenting symptoms. Palatal petechiae, periorbital edema, and rash are less common.

How should infectious mononucleosis be diagnosed?
In the presence of mononucleosis symptoms, a positive heterophile antibody test has a sensitivity of approximately 85% and a specificity of approximately 94% regarding a diagnosis of infectious mononucleosis. However, heterophile antibody tests are negative in 25% of patients during the first week of infection and in 5 to 10% during or after the second week. The detection of at least 10% atypical lymphocytes on a peripheral-blood smear in a patient with mononucleosis has a sensitivity of 75% and specificity of 92% for the diagnosis of infectious mononucleosis. It is reasonable to screen patients who have suspected infectious mononucleosis for group A streptococcal infection with the use of a throat swab and rapid antigen testing or culture.

How is infectious mononucleosis transmitted?
A: EBV transmission occurs predominantly through exposure to infected saliva, often as a result of kissing and less commonly, by means of sexual transmission. The incubation period, from the time of initial exposure to the onset of symptoms, is estimated at 30 to 50 days.

How should patients with infectious mononucleosis be managed?
A: On the basis of clinical experience, supportive care is recommended for patients with infectious mononucleosis. Acetaminophen or nonsteroidal antiinflammatory agents are recommended to manage fever, throat discomfort, and malaise. Adequate fluid intake and nutrition should also be encouraged. Although getting adequate rest is prudent, bed rest is unnecessary. Patients may excrete high levels of EBV in their saliva in the year after onset of infectious mononucleosis, but special precautions against transmission of EBV are not necessary, since most people are EBV seropositive. To minimize the risk of splenic rupture, patients may consider a return to contact sports after a minimum of 3 weeks after onset of symptoms or after they are afebrile, lack clinical symptoms or findings, and feel well enough to play — whichever comes first.

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New England Journal of Medicine - Vol. 362, No. 21