Human Herpes Virus-6 Following Pediatric Allogeneic Hematopoietic Stem Cell Transplantation.

BACKGROUND: Human herpes virus-6 (HHV-6) reactivation after hematopoietic stem cell transplantation (HSCT) is well known and has been linked with several clinical manifestations. The significance of HHV-6 viremia and related complications in this setting is still unclear.

OBJECTIVE: To estimate the incidence of HHV-6 reactivation and associated morbidity in children undergoing allogeneic HSCT.

METHODS: Blood samples obtained weekly (for cytomegalovirus surveillance) from children who underwent allogeneic HCST during the period January 2006-June 2010 were retrospectively tested for the presence of HHV-6 DNA using standard real-time polymerase chain reaction (PCR) assay. Clinical records were reviewed for correlation between viremia and clinical manifestations.

RESULTS: Samples from 39 children were tested. Twenty patients had viral loads above 1000 copies/ml (51%) in at least one sample. Higher viral loads were seen in patients with primary immunodeficiency and in those with cord blood transplant. Attributable symptoms were present in 12 patients (60%) concurrently with positive PCR. Clinical manifestations spontaneously resolved without treatment in most cases, concomitantly with a decrease in viral load.

CONCLUSIONS: HHV-6 reactivation during allogeneic HSCT is common. HHV-6 reactivation should be considered in patients with graft-vs-host disease-like rash, onset of CNS symptoms, delay in engraftment, and in patients after cord blood transplantation.