Fatal varicella zoster virus encephalitis in two patients following allogeneic hematopoietic stem cell transplantation

Background: Reduced cellular immunocompetence following allogeneic hematopoietic stem cell transplantation (aHSCT) increases susceptibility to viral infections. Varicella zoster virus (VZV) reactivation in this setting most commonly manifests as dermatomal herpes zoster but in some cases life-threatening VZV encephalitis occurs. Study design/results: We describe the cases of two patients who presented with shingles 3 and 18 months, respectively, after HLA-matched peripheral blood stem cell transplantation (PBSCT). Unfortunately, in the further clinical course both patients developed fatal VZV encephalitis, despite initial high-dose intravenous therapy with acyclovir and in one case with additional VZV-immunoglobulin. Conclusion: These two cases suggest that rapid intervention with systemic treatment is warranted and raise the question whether initial combination therapy with intravenous acyclovir and foscarnet, VZV vaccination or long-term low-dose acyclovir are needed to improve treatment and clinical outcome in immunocompromised patients, having undergone allogeneic HSCT.