Human herpesviruses types 6 and 7 and febrile seizures

The frequency was studied with which human herpesviruses types 6 and 7 (HHV-6 and HHV-7) occur in the cerebrospinal fluid (CSF) of patients with febrile seizures and matched control patients. CSF samples were prospectively collected from a case series of patients with febrile seizures and from age-, sex-, and race-matched control patients without febrile seizures, all of whom were evaluated in the emergency department of an urban, tertiary care, pediatric medical center. Using polymerase chain reaction, the samples were examined for the presence of viral DNA from HHV-6, HHV-7, herpes simplex viruses types 1 and 2 (HSV-1 and HSV-2), and cytomegalovirus (CMV). CSF from a subset of both groups was also examined for RNA from enteroviruses. During the 7-month, 2-week collection period, a total of 174 patients were evaluated for fever and seizures. Of these, 23 (13.2%) met the study criteria. Their mean age was 1.4 +/- 0.7 years. Sixteen (70%) of the 23 were male. The 23 patients were matched to 21 control subjects. None of the samples from the patients or control subjects had polymerase chain reaction evidence of HHV-6, HHV-7, HSV-1, or HSV-2. All samples from the patients were negative for CMV. One control subject was positive for CMV. The 10 patients and seven control subjects tested for enteroviral RNA were negative. Neither HHV-6 nor HHV-7 appears to be present in the CSF of patients with febrile seizures. What role, if any, they have in the pathogenesis of febrile seizures merits further study.