HHV-6 Encephalitis in Pediatric Unrelated Umbilical Cord Blood Transplantation: Role for Ganciclovir Prophylaxis?

The role of ganciclovir as HHV-6 prophylaxis in unrelated hematopoietic stem cell transplant (HSCT) setting remains controversial.

We performed a 8-year retrospective review of patients received unrelated HSCT from January 2000 to September 2008. From January 2002, ganciclovir prophylaxis 5mg/kg twice daily for 7 days for all unrelated HSCT before transplant was adopted. The other transplant policies including antibacterial, antifungal, antiviral and graft-versus-host disease control policies remained unchange in that period. The prevalence of HHV-6 encephalitis was studied before and after the change in policy.

Fifty-four unrelated HSCT were performed from January, 2000 to September, 2008. Total four cases (7.4%) of HHV-6 encephalitis were diagnosed. Two cases out of 16 cases (12.5%) diagnosed before adoption of the policy; 2 cases out of 38 cases (5.3%) diagnosed afterward. All of them were unrelated umbilical cord blood (UCB) transplant recipients. Two cases had significant residual neurological deficit and refractory seizure. The other two cases died of other transplant-related mortalities.

We conclude that HHV-6 encephalitis is still a rare complication of unrelated HSCT and may be more common in unrelated UCB transplantation. Routine use of ganciclovir as HHV-6 prophylaxis in all unrelated HSCT recipients may not be justified.

No relevant conflicts of interest to declare.