Absence of associations between influenza-associated encephalopathy and human herpesvirus 6 or human herpesvirus 7

Background. Influenza-associated encephalopathy is a severe complication of influenza virus infection, but its pathogenesis is unknown. It was recently suggested that the neurologic complications of influenza, including encephalopathy, are associated with human herpesvirus 6 (HHV-6) and human herpesvirus 7 (HHV-7). Aim. To confirm or refute the association between influenza-associated encephalopathy and HHV-6 or HHV-7. Methods. Cerebrospinal fluid and serum from 25 patients with central nervous system complications of influenza (18 patients with encephalopathy and 7 patients with febrile convulsions) were investigated. The specimens were examined by real time polymerase chain reaction (PCR) and nested PCR for HHV-6 and HHV-7 DNA. Results. In the cerebrospinal fluid samples neither HHV-6 DNA nor HHV-7 DNA was detected by real time PCR or nested PCR. HHV-6 DNA was detected in a single serum sample from a patient with febrile convulsions. Conclusion. In our study there was no association with HHV-6 or HHV-7 in most patients with central nervous system complications of influenza.