A clinically significant viral load of HHV6 DNA was found in children with febrile seizures

HHV-6 was the most common virus found in nasopharyngeal aspirates from young children with febrile seizures, followed by influenza and adenovirus.

Seizures during fevers (febrile seizures, or FS) occur in 2-5% of very young children. Previous research has found active infection with a variety of infectious agents often is present and may be a causal factor.

Rudolph et al. (2021) of the pediatric infectious disease division of the University Children’s Hospital Mannheim conducted a prospective study of the viral load of several viruses in nasopharyngeal aspirates (NPAs) from 184 children with FS, most of whom were hospitalized. The investigators did not measure viral load in blood or cerebrospinal fluid. Viral loads were quantified with highly sensitive qPCR. Of all other pathogens, HHV-6 infection was the most common in this cohort, being found alone or in combination with other viruses in 30% of cases. Found less often, alone or in combination, were influenza, adenovirus and rhinovirus, with other viruses found less frequently. At least one virus was found in 75% of cases. The viral load of HHV6 was found to be 2.72 × 103, which is above the threshold of 1 x103 viral copies/mL that is considered to be an active infection in whole blood (Agut 2015). Also, HHV6 positive cases were significantly younger and less likely to have a family history for FS. 

HboV: human bocavirus
EV: enteroviruses
CoV: coronaviruses
RSV: respiratory syncytial virus
hPIV: human parainfluenza virus
HMPV: human metapneumovirus

This study is consistent with many, but not all, prior studies in suggesting an association between HHV-6 infection and FS. The study did not distinguish between primary infection with HHV-6 and reactivation of prior infection with HHV-6. This study’s prospective design as well as the use of highly sensitive viral detection methodology is a clear strength. Limitations of the study include the exclusion of FS patients who initially presented in an outpatient setting as well as a lack of serological testing. 

Read the full article: Rudolph 2021