Human herpesvirus 7 in pediatric hematopoietic stem cell transplantation

BACKGROUND: Little is known about the significance of human herpesvirus 7 (HHV-7) in pediatric hematopoietic stem cell transplantation (HSCT). OBJECTIVE: To evaluate children post autologous and allogeneic HSCT, with a positive PCR or immunohistochemistry for HHV-7 either from blood, cerebrospinal fluid (CSF) or any other pathology specimen. Clinical data for these patients were collected examining symptoms and signs, engraftment, acute infectious complications, graft versus host disease (GVHD) where applicable, and survival. RESULTS: Between June 1999 and June 2003, 265 HSCT were performed in The Hospital for Sick Children, Toronto, allogeneic (n = 163) and autologous (n = 102). Nine children were positive for HHV-7 at a median of 21 days (range 16-27 days) post-HSCT. All had allogeneic transplantation. The most common underlying diagnosis was acute leukemia and 7 had matched unrelated donor (MUD) transplantation. Eight of the nine patients had grade II-IV acute GVHD and all of them had multiple infectious episodes with fungal, bacterial and other viral pathogens. Although not fully attributed to HHV-7, the clinical syndrome varied from fever, vomiting and diarrhea to septic shock. Four patients died due to GVHD and sepsis. CONCLUSION: HHV-7 was uncommon post-HSCT. It was associated with severe GVHD and sepsis secondary to severe immunosuppression.