Detection of HHV-6 in over a thousand samples: new types of infection revealed by an analysis of positive results.

Background: Clinical manifestations of human herpesvirus-6 (HHV-6) have not been clearly defined, and the role of HHV-6 in human disease remains to be fully elucidated.
Objective: To determine the frequency of HHV-6 infections at Rennes Teaching Hospital and to describe all possible symptoms of such infections.
Study Design: We systematically analyzed in a retrospective study all the samples between May 2003 and December 2004 from patients with HHV-6 by polymerase chain reaction (PCR). Clinical records of patients with positive HHV-6 PCR were recorded. Diagnosis of HHV-6 infection was accepted if all other possible diagnoses had been eliminated.
Results: Over the study period, 1591 PCRs were performed from various tissues, including blood, cerebrospinal fluid, ascitis and tissue biopsies. Forty-three samples from 25 patients tested positive (3%). We describe three groups of clinical manifestations of HHV-6 infection. The first group consisted of neurological complications (32% of patients), including convulsions, encephalitis and chronic psychiatric disorders in immunocompetent patients. The second group consisted of clinical problems relating to gastrointestinal tract, which was found in 9 of our patients (36%). All of these patients were immunocompromised. Four of them presented colitis, and one of them died one month after liver transplantation because of this colitis. The last group of clinical symptoms was associated with maternal-fetal infection leading to abortion following HHV-6 seroconversion during pregnancy.
Conclusion: Three clinical types of HHV-6 infections are described: neurological manifestations including encephalitis in non-immunocompromised patients, digestive problems in immunosuppressed patients and severe maternal-fetal infection.
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