Human herpesvirus 6 (HHV-6) has recently been recognized as an important pathogen in immunocompromised hosts, such as patients who have undergone allogeneic bone marrow transplantation (allo-BMT). Here we report a case of HHV-6 meningoencephalitis in a patient who underwent allo-BMT from an HLA-identical sibling. The patient suffered from headache, high fever, tremor, and disorientation on day 35 after allo-BMT. Findings at magnetic resonance imaging, electroencephalography, and routine cerebrospinal fluid (CSF) examination suggested the presence of viral meningoencephalitis. We diagnosed HHV-6 meningoencephalitis by means of polymerase chain reaction (PCR) analysis of a CSF specimen. Successful treatment was achieved with ganciclovir. Because HHV-6 encephalitis has a potentially fatal and fulminant course, it is necessary that HHV-6 encephalitis be recognized as one of the central nervous system complications that can follow allo-BMT. PCR analysis for HHV-6 in the CSF specimen is necessary for appropriate diagnosis and treatment.

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The distribution of human herpesvirus 6 (HHV-6) and varicella-zoster virus (VZV) was examined in autopsy samples from a fatal case with both virus infections. A 9-month-old boy developed convulsive seizures followed by macular skin rashes, rapidly progressed to brain death, and died 15 days after the onset, when signs of varicella were noted. An isolation of HHV-6 from blood and evaluation of antibody activities to various viral agents including HHV-6 were performed before his death. Postmortem examinations included: (i) isolation of HHV-6 and VZV from tissues or organs; (ii) detection of both virus antigens in tissues or organs by an indirect immunofluorescent assay using monoclonal antibodies to both viruses; (iii) amprification of both viruses and human herpesvirus 7 DNA sequences by a nested polymerase chain reaction assay; and (iv) endonuclease digestion of amplified products of HHV-6 DNA for differentation of variants A and B.Human herpesvirus 6 DNA was detected in peripheral blood mononuclear cells (PBMC) and plasma obtained at the eruptive stage but present only in .PBMC 15 days after, indicating the primary infection with HHV-6, although the virus was not isolated from the same blood sample and a significant rise in the antibody titers to HHV-6 was not observed. Both virus antigens and DNA were detected in various tissues or organs obtained at autopsy, but only VZV was isolated from these samples, suggesting disseminated infection with both viruses in an infant. All the amplified products of HHV-6 DNA were variant B. Among the findings for the distribution of virus antigens, it was noteworthy that HHV-6 antigen was demonstrated in the endothelial cells of small vessels in the frontal lobe of the brain. There was no evidence of HHV-7 infection. These data indicate that the primary HHV-6 infection closely followed by the primary VZV infection had the potential hazard of an unexpected and apparently life-threatening event, in which disseminated infections with both viruses were noted in multiple tissues or organs including the brain. Key wordsexanthem subitum, human herpesvirus 6, human herpesvirus 7, varicella, varicella-zoster virus.

An 86-year-old man with nonspecific interstitial pneumonia and poorly controlled diabetes mellitus came to our hospital with complaints of painful stomatitis and tongue ulcers lasting for 2 months (Fig. 1). He had been taking azathioprine at 50 mg/day and predonisolone, which was gradually tapered from 50 to 12.5 mg/day, for a period of 3 months.The patient tested positive for cytomegalovirus (CMV) antigen (pp65) in 490 of 150,000 cells. A biopsy of the tongue ulcer showed enlarged endothelial cells with inclusion bodies. CMV immunofluorescent staining was positive, and herpes simplex staining was negative. The tongue ulcer improved rapidly following the initiation of ganciclovir treatment.Oral lesions caused by CMV have been reported in transplantation recipients [1]. Human immunodeficiency virus patients are also known to suffer from oral ulcers caused by CMV [2]. However, there has been no report to date of a CMV-related oral ulcer that occurred during steroid or immunosuppressant treatment.The involvement of CMV should be considered when patients who are prescribed steroid or immunosuppressant agents develop oral ulcers.

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