Encephalitis caused by human herpesvirus-6 in transplant recipients: relevance of a novel neurotropic virus.
BACKGROUND
Human herpesvirus-6 (HHV-6) is a neurotropic virus. Encephalitis is a significant clinical manifestation of HHV-6; however, sparse data on this entity exist in transplant recipients.


METHODS
Cases of HHV-6 encephalitis reported in the literature (13 bone marrow transplant recipients and 1 liver transplant recipient) were reviewed. The diagnosis was established in all by viral isolation and/or detection of HHV-6 DNA in the cerebrospinal fluid by polymerase chain reaction or histopathologic method.


RESULTS
HHV-6 encephalitis occurred a median of 45 days (range 10 days to 15 months) after transplantation. Mental status changes, ranging from confusion to coma (92%), seizures (25%), and headache (25%) were the predominant clinical presentations. Focal neurologic findings occurred in only 17% of the patients. Twenty-five percent of the patients had fever; however, the height of fever (< or =40 degrees C) in febrile patients was striking. Cerebrospinal fluid pleocytosis was generally lacking. Abnormal neuroimaging findings, characterized by low-attenuation lesions in the posterior cerebral lobes, were present only in 17% of the patients. Overall mortality in patients with HHV-6 encephalitis was 58% (7 of 12); 42% (5 of 12) of the deaths were caused by HHV-6. Cure was documented in 7 of 8 patients who received ganciclovir or foscarnet for > or =7 days, compared with 0% (0 of 4) in those who did not receive these drugs or received them for < 7 days (P=.01).


CONCLUSIONS
HHV-6 may be associated with encephalitis after transplantation and warrants consideration in transplant recipients with encephalitis of unidentifiable etiology.
Singh
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Veterans Affairs Medical Center and University of Pittsburgh, Thomas E Starzl Transplantation Center, Pennsylvania, USA. nis5+@pitt.edu
Paterson
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DL
D000293:Adolescent; D000328:Adult; D016026:Bone Marrow Transplantation / Q000009:adverse effects* / Q000401:mortality; D018792:Encephalitis, Viral / Q000188:drug therapy / Q000209:etiology*; D005260:Female; D006566:Herpesviridae Infections / Q000188:drug therapy / Q000209:etiology*; D015654:Herpesvirus 6, Human / Q000302:isolation & purification*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012307:Risk Factors