HHV-6-related secondary graft failure following allogeneic bone marrow transplantation

We report the case of an 11-year-old boy who underwent allogeneic bone marr ow transplantation (BMT) for relapsed acute lymphoblastic leukaemia. Despit e adequate engraftment, on day 45 he developed marrow aplasia with haemopha gocytosis. HHV-6 was detected in blood and bone marrow by nested PCR, Retro spective testing showed that viraemia had started on day 24. Following ther apy with foscarnet and ganciclovir, viral load declined to undetectable lev els and his donor marrow recovered contemporaneously, This case suggests th at HHV-6 may be a treatable cause of graft failure following BMT and provid es clinical and virological evidence For the anti-HHV-6 activity of gancicl ovir and foscarnet.