Longitudinal study of human herpesvirus 6 infection in organ transplant recipients.

Human herpesvirus 6 (HHV-6) has been frequently isolated from immunocompromised patients. To determine if a routine survey of HHV-6 infection is needed after organ transplantation, as is the case for human cytomegalovirus infection, we observed patients who had received kidney, liver, and kidney-liver transplants; these patients were followed up for the first 3 months after transplantation. HHV-6 infection was diagnosed by isolation of the virus and by the results of serological tests. Antibodies to HHV-6 were detected in 28 (87.5%) of the 32 recipients, before the transplant, whereas only 4 (12.5%) of the 32 recipients were seronegative for HHV-6. After engraftment, HHV-6 infection occurred in 10 (31%) of the 32 recipients; infection was diagnosed by isolation of the virus (6 of 32 recipients) or by the results of serological tests (4 of 32 recipients). Regardless of whether they had HHV-6 primary infection or reactivation, severe clinical manifestations were observed only in patients who had concomitant cytomegalovirus infection, and no correlation could be found between graft rejection and HHV-6 infection. These results suggest that HHV-6 infection occurs frequently in organ transplant recipients and that it is usually not associated with severe clinical manifestations unless accompanied by a concomitant CMV infection.