Human Herpes Virus-6 Encephalitis Following Autologous Blood and Marrow Transplant

Human herpesvirus-6 (HHV-6) is a highly prevalent virus that establishes lifelong latency in human hosts. Symptomatic HHV-6 reactivation rarely occurs in immunocompetent individuals and is best described in immunosuppressed patients such as recipients of bone marrow transplants (BMT). In that setting, HHV-6 reactivation has been associated with fever, rash, pneumonitis, encephalitis, and delayed engraftment. While these complications are well documented in allogeneic transplant, the clinical impact of such reactivation is not well known in autologous BMT. We described a case of HHV-6-associated encephalitis in a previously heavily treated patient with multiple myeloma (MM) following a second autologous BMT, and discuss the need for clinicians to be aware of the potential clinical impact of HHV-6 following autologous BMT in the era of immunomodulatory agents.