Varicella-associated thrombocytopenia: clues to the etiology of childhood idiopathic thrombocytopenic purpura.

The temporal patterns of varicella-associated thrombocytopenia in five children seen at the Johns Hopkins Hospital suggest the existence of at least two pathogenetic mechanisms: one "infectious," with thrombocytopenia during the period of viremia; the other "post-infectious," with thrombocytopenia continuing for weeks or months afterward. Because of the subtleties of many viral illnesses, the frequency with which an active infection produces childhood idiopathic thrombocytopenic purpura may be underestimated. Studies to evaluate this hypothesis may enhance our knowledge of etiologic factors and enable more rational therapy.