Diagnosis and Treatment of Infectious Mononucleosis
The diagnosis of infectious mononucleosis is primarily made using heterophile antibody testing (Monospot test), while treatment is mainly supportive with adequate hydration, analgesics, and rest, as there is no specific antiviral therapy recommended for routine cases. 1
Diagnostic Approach
Initial Clinical Evaluation
- Infectious mononucleosis should be suspected in patients 10-30 years old presenting with the classic triad of fever, tonsillar pharyngitis, and lymphadenopathy 2
- Additional suggestive findings include periorbital/palpebral edema (in one-third of patients), splenomegaly (50%), hepatomegaly (10%), and maculopapular rash (10-45%) 2
- Fatigue, which may be profound, is a common symptom that can persist for several months 3
Laboratory Testing
- First-line test: Heterophile antibody test (Monospot) becomes positive between the sixth and tenth day after symptom onset 4, 1
- Complete blood count typically shows:
- Peripheral blood leukocytosis with lymphocytes making up at least 50% of white blood cells
- Atypical lymphocytes constituting more than 10% of the total lymphocyte count 2
- An atypical lymphocytosis of at least 20% or atypical lymphocytosis of at least 10% plus lymphocytosis of at least 50% strongly supports the diagnosis 3
Additional Testing When Heterophile Test Is Negative
- When clinical suspicion remains high despite a negative heterophile test, EBV-specific serologic testing is recommended 1
- EBV antibody testing should include:
- Interpretation of EBV serology:
- Presence of VCA IgM (with or without VCA IgG) antibodies in the absence of EBNA antibodies indicates recent primary EBV infection
- Presence of EBNA antibodies indicates infection more than 6 weeks prior 4
Differential Diagnosis
- Consider other causes of mononucleosis-like illness when heterophile tests are negative:
Treatment Approach
Supportive Care
- Treatment is mainly supportive and includes:
- Bed rest should not be enforced, but activity should be guided by the patient's energy level 3
Activity Restrictions
- Patients should be withdrawn from contact or collision sports for at least 4-8 weeks after symptom onset or while splenomegaly is present to reduce the risk of splenic rupture 2, 3
Medications
- Corticosteroids are not recommended for routine treatment but may benefit patients with:
- Acyclovir and antihistamines are not recommended for routine treatment of infectious mononucleosis 3
Complications and Prognosis
Potential Complications
- Splenic rupture is the most feared complication, occurring in 0.1-0.5% of patients 2
- Other potential complications involve:
- Pulmonary system
- Ophthalmologic system
- Neurologic system
- Hematologic system 6
- Infectious mononucleosis is a risk factor for chronic fatigue syndrome 2
Prognosis
- Most patients have an uneventful recovery 2
- Fatigue, myalgias, and increased need for sleep may persist for several months after the acute infection has resolved 3
Common Pitfalls and Caveats
- False-negative heterophile antibody results are common early in the course of infection and in young children under 10 years 4, 1
- False-positive heterophile antibody results may occur in patients with leukemia, pancreatic carcinoma, viral hepatitis, and CMV infection 4, 1
- Approximately 5-10% of patients who have been infected with EBV fail to develop antibodies to EBNA antigen 4, 1
- Over 90% of normal adults have IgG antibodies to VCA and EBNA antigens, reflecting past infection 1