title: Post-varicella thrombocytopenic purpura.
abstract: OBJECTIVE
  The aim of the study was to characterize the clinical course of post-varicella idiopathic thrombocytopenic purpura (ITP) and to asses the risk of acquiring ITP after varicella infection.
  
  
  METHODS
  A retrospective study of all children diagnosed with ITP in a tertiary medical centre during 1998-2008. Findings were compared with the Intercontinental Childhood ITP Study Group database. The risk of acquiring ITP after a varicella infection was assessed.
  
  
  RESULTS
  Ten children were diagnosed with post-varicella ITP. The incidence of post-varicella ITP was 1.9% amongst children diagnosed with ITP and 1.1% amongst children hospitalized for varicella. ITP was diagnosed, on average, 8.5 days after the onset of the varicella rash. The female-to-male ratio was 1:1.5. The average minimal platelet count was 9.5 × 10⁹ platelets/L. Post-varicella ITP had an acute course in 80% of cases and a chronic course in the remaining 20%. Bleeding episodes occurred in three patients. During the follow-up period, 11 patients with previously diagnosed ITP developed varicella. The infection had no apparent affect on the platelet count of the children with acute ITP, but caused a relapse in 71% of the patients with chronic ITP.
  
  
  CONCLUSIONS
  Post-varicella ITP has similar clinical features and course to non-varicella associated ITP. The calculated risk of ITP as a complication of varicella infections is approximately 1:25,000.
authors.affiliation: Department of Pediatrics B, Schneider Children's Medical Center of Israel, Petah Tiqwa, Israel.
authors.forename: Achiya
authors.initials: A
authors.lastname: Amir
authors.forename: Oded
authors.initials: O
authors.lastname: Gilad
authors.forename: Joanne
authors.initials: J
authors.lastname: Yacobovich
authors.forename: Oded
authors.initials: O
authors.lastname: Scheuerman
authors.forename: Hannah
authors.initials: H
authors.lastname: Tamary
authors.forename: Ben-Zion
authors.initials: BZ
authors.lastname: Garty
mesh_terms: D000293:Adolescent; D002644:Chickenpox / Q000453:epidemiology* / Q000628:therapy; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D015994:Incidence; D007557:Israel / Q000453:epidemiology; D008297:Male; D010976:Platelet Count; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000453:epidemiology* / Q000503:physiopathology / Q000821:virology*; D012189:Retrospective Studies; D012307:Risk Factors