Background: The immunosuppressed state in patients undergoing hematopoietic stem cell transplantation (HSCT) predisposes them to activation of latent viral infections such as herpesvirus types 6 and 7 (HHV6 and HHV7). We aimed to evaluate the incidence, manifestations, outcomes, and risk factors of HHV 6 and HHV 7 infections after pediatric hematopoietic stem cell transplantation.
Material and methods: We performed 106 HSCTs (86 allogeneic and 20 autologous) on 94 children (56 boys, median age 7.1 years) during 2006-2012. Patients suspected to have HHV6 or HHV7 infections were tested using polymerase chain reaction on serum and/or cerebrospinal fluid.
Results: Among the 63 patients tested for HHV, 10 patients (15.9%) were infected (HHV-6 (n=6), HHV-7 (n=4)) at a median of 18 days post-HSCT (cumulative incidence 11.5% at 1 year). Manifestations included fever (90%), rash (70%), hepatitis (80%), pneumonitis (50%), central nervous system (CNS) manifestations (40%), and graft failure (10%). One patient had persistent CNS infection despite treatment with foscarnet, ganciclovir, and cidofovir. Seven patients cleared herpesvirus after a median of 22 days. Four patients died (relapse of malignancy [n=3], acute graft-versus-host disease [aGVHD] [n=1]). Herpesvirus infections were associated with adenovirus infection (p=0.001) and severe (grade III-IV) aGVHD (p=0.037).
Conclusions: We concluded that HHV6 and HHV7 infections are common after pediatric HSCT. Most infections were self-limited and could be associated with adenovirus infection and severe aGVHD. Further studies are needed to evaluate predictors of severe morbidity or mortality, and define optimal prophylaxis and treatment.