Abstract
Human herpes virus-6 (HHV-6) is the main cause of viral encephalitis in patients undergoing allogeneic hematopoietic cell transplantation (allo-HCT). From January 2005 to December 2014, 97 patients with HHV-6 encephalitis were reported in the EBMT registry. The incidence was 0.45% after the first allo-HCT and varied with the type of donor and of stem cell source: sibling donor 0.06%, unrelated donor 0.68%, haploidentical donor 0.51%, cord blood 2.14%, bone marrow 0.20%, peripheral blood 0.44%. HHV-6 encephalitis occurred at a median time of 31 days from allo-HCT (range 16–317 days). With a median follow-up of 5.28 years, the 5-yr OS was 24.7%. The causes of death were: disease relapse/progression 11, infection 23, non-infectious cause 33, not specified 5. Forty-four deaths (61.1%) occurred within 90 days from diagnosis of HHV-6 encephalitis and in 24 HHV-6 encephalitis was considered a contributory cause. Eight-seven patients received treatment mainly with foscarnet or ganciclovir. In multivariate analysis, bone marrow/peripheral blood stem cell source and nonmyeloablative conditioning regimen were significant factors for lower survival. In conclusion, the incidence of HHV-6 encephalitis was low but associated with high mortality irrespective of antiviral treatment. This confirms the need for further research in this setting.
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Data availability
The datasets generated and analysed during the current study are available from the corresponding author on reasonable request after approval of the scientific board of the Infectious Diseases Working Party of EBMT.
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KNW designed the study and revised critically the manuscript. NK collected the data. GT performed the statistical analysis. KP and SC analysed the data and wrote the paper. RZ, GNF, AS, HE, MGV, JMFN, NC, MC, RM, MG, HS, JP, JS, AN, AK, MG, NK, MJPG, MY, TG, CR, AC, MLD, AAA, MIR, MM, JS, RDLC, PL, DA, collected and reported the data to the EBMT Registry and revised critically the manuscript. All authors approved the final version of the manuscript.
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This is a Registry study conducted under the scientific supervision of IDWP-EBMT. All authors have no conflict of interest concerning this study to disclose.
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Perruccio, K., Ward, K.N., Tridello, G. et al. Clinical characteristic and outcome of HHV-6 encephalitis after allogeneic hematopoietic cell transplantation: A study of Infectious Disease Working Party of EBMT. Bone Marrow Transplant 60, 1243–1248 (2025). https://doi.org/10.1038/s41409-025-02638-7
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DOI: https://doi.org/10.1038/s41409-025-02638-7
