title: Human herpesvirus-6 encephalitis during hematopoietic stem cell transplantation leads to poor prognosis.
abstract: BACKGROUND
  Indications for the application of hematopoietic stem cell transplantation (HSCT) from alternative donors have remarkably broadened in scope; however, the incidence of infections that lead to failure of HSCT, such as human herpesvirus-6 (HHV-6) encephalitis, has also increased.
  
  
  METHODS
  We analyzed risk factors for symptomatic HHV-6 reactivation and the development of HHV-6 encephalitis in 140 consecutive adult patients who received allogeneic HSCT at our institution. Stem cell sources for the recipients were as follows: related-donor bone marrow in 40, related-donor peripheral blood in 5, unrelated bone marrow in 67, and unrelated cord blood in 28.
  
  
  RESULTS
  Symptomatic HHV-6 reactivation occurred in 22 patients (16%), and 11 patients manifested encephalitis. Multivariate Cox proportional hazards regression analysis identified cord blood cell transplantation (CBT) as an independent predictor of HHV-6 reactivation (P = 0.008). Hyponatremia or hypernatremia at the time of HHV-6 reactivation was detected before the development of HHV-6 encephalitis in 2 or 4 patients, respectively. Two patients died of HHV-6 encephalitis and 6 patients died of relapse of underlying diseases. Survival analysis identified higher risk of the disease (P = 0.021) and HHV-6 encephalitis (P = 0.003) as independent risk factors for reduced overall survival.
  
  
  CONCLUSIONS
  In cases involving CBT or unrelated-donor transplantation, patients should be carefully monitored for the symptomatic reactivation of HHV-6.
authors: Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors: Y
authors: Y
authors: Shimazu
authors: T
authors: T
authors: Kondo
authors: T
authors: T
authors: Ishikawa
authors: K
authors: K
authors: Yamashita
authors: A
authors: A
authors: Takaori-Kondo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018792:Encephalitis, Viral / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation / Q000009:adverse effects*; D015654:Herpesvirus 6, Human / Q000302:isolation & purification*; D006801:Humans; D006955:Hypernatremia / Q000209:etiology; D007010:Hyponatremia / Q000209:etiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D016016:Proportional Hazards Models; D012307:Risk Factors; D019349:Roseolovirus Infections / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D055815:Young Adult