HHV-6 encephalitis is a significant concern in the post-transplant setting, particularly in the setting of cord blood transplantation. A 2012 review indicated that nearly 10% of all cord blood transplant recipients develop HHV-6 encephalitis, compared to only 1% of patients receiving traditional SCT (Scheurer 2012). For more information, please visit the HHV-6 Foundation’s webpage on HHV-6 Encephalitis.
Risk Factors for the Development of HHV-6 Encephalitis in Transplantation:
1. Use of umbilical cord blood (Scheurer 2012)
2. Alemtuzumab (Vu 2007)
3. Thymoglobulin conditioning (Hill 2011)
4. Steroid administration (Ogata 2010)
5. Unrelated donors (Betts 2011)
6. Two or more HSCT (Mori 2010)
HHV-6 and Cognitive Dysfunction
HHV-6 reactivation is the most common cause of mental confusion among post-transplant patients (Zerr 2011). HHV-6-associated encephalitis also presents as retrograde and anterograde amnesia.
HHV-6 and GVHD
HHV-6 reactivation has been increasingly associated with acute graft-versus-host disease (aGVHD) and allograft rejections in the transplant setting. A recent survey of 235 allogeneic stem cell transplant patients indicated that post-transplant HHV-6 reactivation is strongly associated with delayed platelet engraftment, early post-transplantation mortality, and the development of acute GVHD (Dulery 2011). To view the latest research on this relationship, download the HHV-6 Foundation’s IDWeek 2012 handout on HHV-6 & GVHD.