Scientists have discovered evidence suggesting a herpesvirus may be responsible for some cases of meningitis and encephalitis.
Human herpesvirus 6 (HHV-6) is one of the most prevalent in humans. There are two variants of HHV-6, HHV-6A and HHV-6B which is attributed to a common childhood disease characterized by a high fever and rash. Studies indicate that by age 3 the majority of children have been infected by HHV-6, after which the virus persists in the salivary glands into adulthood. The virus may remain dormant or reactivate in immunocompetent or immunocompromised individuals.
Over a span of four years, researchers from the New York State Department of Public Health, Albany and SUNY, Albany collected specimens from patients hospitalized with symptoms of encephalitis and meningitis, and tested them for the presence of HHV-6. The majority of the specimens were taken from cerebrospinal fluid and some of the symptoms exhibited by the patients include fever, altered mental status, and abnormal CSF profile, as well as seizures in those ages 3 and under.
Results showed that 26 specimens from 24 patients were positive for HHV-6, of which 20 were identified as the HHV-6B strain. Forty-two percent of the patients were age 3 or under, possibly indicating primary infection, while the remaining patients ranging from 4 to 81 years old were probably experiencing viral reactivation.
"The detection of HHV-6 in specimens from patients diagnosed with encephalitis or meningitis, in the absence of a positive PCR result for other agents, strongly suggests a role for HHV-6 in the pathogenesis of these central system diseases," say the researchers.
Journal reference: N.P. Tavakoli, S. Nattanmai, R. Hull, H. Fusco, L. Dzigua, H. Wang, M. Dupuis. 2007. Detection and typing of human herpesvirus 6 by molecular methods in specimens from patients diagnosed with encephalitis or meningitis. Journal of Clinical Microbiology, 45. 12: 3972-3978.
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