Encephalitis caused by an unusual human herpes virus type 6 and Toxoplasma gondii co-infection in a cord blood transplant recipient

• Human herpes virus type 6 (HHV-6) reactivation could promote the reactivation of Toxoplasma gondii. • The T. gondii-seropositive patient is at high-risk of reactivation after cord blood transplantation. • Cord blood transplantation is an important risk factor for opportunistic diseases.