Human herpesvirus 6 (HHV-6) has been associated with CNS dysfunction, such as febrile seizures, encephalitis, meningitis, and possibly multiple sclerosis. These manifestations have been reported in both immunocompetent and immunocompromised patients.101
HHV-6 infection is nearly universal in infancy or early childhood. Convulsive episodes tend to occur during the pre-eruptive stage of exanthem subitum,102 but they can appear late and be recurrent.
Whether HHV-6 infection causes febrile seizures is controversial. A prospective study of pediatric patients presenting in the emergency room found that HHV-6 infections accounted for 20% of ER visits for febrile illnesses among children 6–12 months old. No primary HHV-6 infection was found among infants and young children with acute nonfebrile illness or among control subjects without any illness. Of these patients with acute febrile illness and documented HHV-6 infection, 13% had seizures. Furthermore, HHV-6 infection was associated with one-third of all febrile seizures in children up to 2 years old.103
In another study, Barone and colleagues prospectively evaluated febrile convulsions in 42 children to investigate the association between acute HHV-6 infection and first-time febrile convulsions. Primary HHV-6 infection was found in 21% of the children, documented by viral culture, serologic studies, or both.104 However, a case-control study failed to find a statistically significant association between HHV-6 infection and first-time or recurrent febrile seizures.105 (See further discussion of febrile seizure and infection.)
Reviewed and revised March 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
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