HHV-6 DNA found in the spinal fluid of 8.8% of infants evaluated for encephalitis

HHV-6 DNA found in the spinal fluid of 8.8% of infants with encephalitis

Investigators led by Jila Yavarian of Tehran University of Medical Sciences have found HHV-6 DNA in cerebrospinal fluid (CSF) samples of 8.8% of 114 infants evaluated for possible encephalitis. None of them had the rash typical of primary HHV-6B infection.

The children presented with symptoms that included convulsions and altered levels of consciousness. All were younger than 13 months, and 95 (83%) were experiencing their first known episode of febrile convulsions at the time of admission. The HHV-6+ patients did not demonstrate significant differences in clinical presentation compared to the patients without HHV-6 infection. Unfortunately, the virus species was not typed, and ciHHV-6 status was not determined.

There have been very few studies of HHV-6 DNA in spinal fluid of infants with seizures or encephalitis outside of Japan. In one study by Yoshikawa and colleagues, HHV-6 DNA was found in 24% (21/86) cases of exanthema subitum associated encephalopathy (Yoshikawa 2009).

Studies of encephalitis in immunocompetent adults have varied depending on the sensitivity of the assay used. For example, in a 2003 study conducted by Carol Glaser through the California Encephalitis Project, only 1 case out of 208 tested positive for the presence of herpesviruses, based on a “herpesvirus consensus PCR” that is insensitive for HHV-6 (Glaser 2003). On the other hand, when the same samples were tested using a sensitive method in Steve Jacobson’s NINDS laboratory, 40% of the encephalitis samples were positive for HHV-6 DNA (Yao 2009). The authors also cite a previous study in which HHV-6 DNA was found in 6% (9/150) of Iranian children with meningoencephalitis.

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