Human herpesvirus 6 antigenaemia in allogeneic stem cell transplant recipients: impact on clinical course and association with other beta-herpesviruses.

Human herpesvirus 6 (HHV-6) antigenaemia was prospectively studied in 58 adult allogeneic stem cell transplant (SCT) recipients. Altogether 42 of 58 recipients (72%) demonstrated HHV-6 specific antigens in peripheral blood mononuclear cells after SCT, 22 of 36 (61%) when the donor was a sibling and 20 of 22 (91%) when the donor was unrelated. The cumulative incidence of HHV-6A, HHV-6B, HHV-7, and cytomegalovirus antigenaemia during the first 6 months after SCT was 33%, 62%, 44% and 63% respectively. The median day of the onset of each antigenaemia was +24, +4, +59, and +46 after SCT respectively. There were no clinical findings related to HHV-6A and HHV-7 antigenaemias. A rash was diagnosed in 10 of 38 (26%) HHV-6B antigenaemia positive patients during the first month after SCT compared with one of 20 (5%) HHV-6B negative patients. Of the HHV-6B antigenaemia cases, six of 10 rashes were treated as acute graft-versus-host disease (GVHD) and four of 10 were considered to be of a viral origin. Fifteen patients had acute GVHD diagnosed. Acute GVHD manifested statistically significantly (P = 0.034) earlier in the nine patients with HHV-6B antigenaemia compared with the six patients who were HHV-6B negative.