Infectious Mononucleosis: Symptoms and Treatment
Primary Symptoms
Infectious mononucleosis presents with a classic triad of fever, tonsillar pharyngitis, and lymphadenopathy, with profound fatigue that typically resolves within three months. 1
Cardinal Features
- Fever: Often reaches 40°C (104°F), though may be mild or absent in some patients 2
- Sore throat with tonsillar pharyngitis: One of the most prominent presenting symptoms 1
- Cervical lymphadenopathy: Particularly posterior cervical or auricular nodes are characteristic 3
- Profound fatigue: The hallmark symptom that may persist for several months after acute infection resolves 3
Common Physical Findings
- Splenomegaly: Occurs in approximately 50% of cases 1
- Hepatomegaly: Present in approximately 10% of cases 1
- Periorbital/palpebral edema: Bilateral eyelid swelling occurs in one-third of patients 1
- Palatal petechiae: Supportive diagnostic finding 3
Skin Manifestations
- Maculopapular rash: Occurs in 10-45% of cases, widely scattered and erythematous 1
- Antibiotic-associated rash: Particularly common when ampicillin or amoxicillin is administered (a key pitfall to avoid) 2
Laboratory Findings
Hematologic Abnormalities
- Peripheral blood leukocytosis: Present in most patients with lymphocytes comprising at least 50% of the differential 1
- Atypical lymphocytosis: More than 10% of total lymphocyte count 1
- Atypical lymphocytosis ≥20% OR atypical lymphocytosis ≥10% plus lymphocytosis ≥50% strongly supports the diagnosis 3
Other Laboratory Findings
- Elevated liver function tests: Mild transaminase elevations are common 2, 4
- Hematologic complications: Anemia, thrombocytopenia, and neutropenia can occur in severe cases 2
Diagnostic Testing
Heterophile Antibody Testing
- Monospot test: The most widely used method and typically sufficient with classic clinical presentation 1
- Important caveat: False-negative results are relatively common early in infection 3
EBV-Specific Serology
- When to use: Required when mononucleosis-like illness presents with negative monospot test 1
- VCA IgM with or without VCA IgG, in the absence of EBNA antibodies: Indicates recent primary infection 2
Severe Complications Requiring Immediate Attention
Life-Threatening Complications
- Splenic rupture: Occurs in 0.1-0.5% of patients and is potentially fatal 1
- Respiratory compromise or severe pharyngeal edema: May require corticosteroid intervention 3
- Persistent high fever unresponsive to antipyretics: Warrants medical evaluation 2
Less Common Severe Manifestations
- Neurological complications: Headache and rare severe neurological symptoms 2
- Interstitial pneumonitis: Can develop in some cases 2
Treatment Approach
Supportive Care (Mainstay of Treatment)
Treatment is primarily supportive, as infectious mononucleosis is generally benign and self-limited. 1
- Adequate hydration, analgesics, and antipyretics: Core symptomatic management 3
- Activity modification: Reduction of activity and bed rest as tolerated, guided by patient's energy level rather than enforced bed rest 3
- Adequate rest: Essential but should not be rigidly enforced 3
Activity Restrictions
Patients must avoid contact sports or strenuous exercise for 8 weeks or while splenomegaly is present to prevent splenic rupture 1
Medications NOT Routinely Recommended
- Corticosteroids: Not recommended for routine treatment 3
- Exception: May benefit patients with respiratory compromise or severe pharyngeal edema 3
- Acyclovir: Not recommended for routine treatment 3
- Antihistamines: Not recommended for routine treatment 3
Critical Pitfall to Avoid
Never prescribe ampicillin or amoxicillin for suspected streptococcal pharyngitis without ruling out mononucleosis first, as this causes a characteristic rash in the majority of mono patients 2
Clinical Course and Prognosis
- Acute symptoms: Most symptoms, signs, and laboratory abnormalities return to normal by 1 month 4
- Protracted symptoms: Fatigue, cervical lymphadenopathy, and pharyngitis may improve more slowly 4
- Long-term fatigue: May persist for several months but typically resolves within three months 1, 3
- Chronic fatigue syndrome: Infectious mononucleosis is a recognized risk factor 1
- Overall prognosis: Most patients have an uneventful recovery 1