Prior administration of foscarnet may result in viremia-negative post-transplant human herpesvirus-6B encephalitis

Abstract

 A 39-year-old man with myelodysplastic syndrome achieved complete remission with azacitidine chemotherapy. He received an unrelated bone marrow transplantation. A high fever and skin rash began on day 4, which resolved with hydrocortisone started on day 9. On the same day, foscarnet treatment was initiated for the prophylaxis of cytomegalovirus infection. He had a generalized seizure on day 23. As empiric therapy, foscarnet was increased to a therapeutic dose against human herpesvirus-6B (HHV-6B) encephalitis, which was diagnosed by polymerase chain reaction (PCR) analysis of cerebrospinal fluid. Quantitative real-time PCR of the plasma sample was negative for HHV-6B. He responded well to a 21-day course of foscarnet treatment with almost complete resolution of his symptoms.

 In the case of HHV-6 encephalitis during the course of foscarnet, PCR examination may reveal HHV-6B negativity in plasma samples. Therefore, it is important to sample cerebrospinal fluid specimens for HHV-6B detection.