Medline ® Abstract for Reference 99 of ‘Human herpesvirus 6 infection in hematopoietic cell transplant
Viruses have been implicated in the development of neurodegenerative diseases, such as Alzheimer’s, Parkinson’s, and multiple sclerosis. MATERIALS AND METHODS: This retrospective study was performed with institutional review board committee approval by using a waiver of informed consent. Administration of cidofovir followed by foscarnet was associated with total clearance of human herpesvirus 6 infection. Multivariate analysis identified myeloablative conditioning (hazard ratio [HR], 1.9; P = .004), umbilical cord blood transplantation (UCBT) (HR, 2.0; P = .003), and male sex (HR, 1.6; P = .04) as risk factors for displaying high-level HHV-6 reactivation. Cumulative incidence (CI) of positive HHV-6 DNA and high-level HHV-6 reactivation (plasma HHV-6 DNA ≥104 copies/ml) at day 70 after HCT was 72.2% and 37.0%, respectively. Retrospective analyses of plasma revealed the presence of viral DNAemia prior to the onset of disease in two subjects. Breakthrough HHV-6 encephalitis occurred following PFA prophylaxis in three patients, and incidence of HHV-6 encephalitis did not differ between cohort 1 (9.9%) and cohort 2 (4.5%, P=0.24).
Among the seven HHV6-negative patients, six had abnormalities in the hippocampus but only two showed extrahippocampal involvement, which was restricted to the amygdala. Thus, HHV-6 is considered to be one of the causative agents for limbic encephalitis that develops in immunocompromised patients.