Paediatrics: Rash: infectious mononucleosis

Rash: infectious mononucleosis

Infectious mononucleosis is caused by EBV (90%) and CMV. The source is oropharyngeal secretion. Virus infects B lymphocytes in pharyngeal lym-phoid tissue and then spreads to the rest of the lymphoid system.

Signs and symptoms

• Prodrome: flu-like illness (headache, low-grade fever, and chills) for 3–5 days. The incubation period is 4–6wks.

• Features: exudative pharyngitis; generalized, tender lymphadenopathy; hepatosplenomegaly; widespread erythematous macular rash, especially if inadvertently treated with ampicillin; lethargy.

Diagnosis

• Classic triad: lymphocytosis (80–90% of WBC); 10% atypical lymphocytes on peripheral blood film; positive serology for EBV.

• Monospot test: a low-sensitivity test with false positives occurring in lymphoma and hepatitis.

• Other. IgM and IgG are raised early in the disease; raised liver function tests; mild thrombocytopenia. Quantitative PCR in immunosuppressed (not for routine diagnosis).

Management

• Symptoms: supportive care

• Splenomegaly: patients with splenomegaly should avoid contact sports for 1mth, and adolescents should avoid alcohol.

Complications

• GI and abdominal: hepatitis, splenomegaly, and splenic rupture.

• CNS: aseptic meningitis, encephalitis, Guillain–Barré syndrome.

• Post viral tiredness: is self-limiting, but may take months to resolve.

Other. lymphoma, orchitis, myocarditis, pneumonia.