Table 1_Clinical and metagenomic characterization of HHV-6 versus HHV-7 encephalitis in immunocompetent children.xlsx

HHV-6 cases mainly occurred in infants and young children, whereas HHV-7 cases were predominantly observed in older children. Fever and seizure-related symptoms were the most common clinical manifestations. Peripheral inflammatory markers, CSF parameters, and neuroimaging findings showed heterogeneous patterns among patients.

CSF mNGS detected HHV-6 or HHV-7 sequences in all included cases, with variable sequencing read counts (HHV-6: median 257 reads, range 55–52, 686; HHV-7: median 2, 635 reads, range 457–26, 355). The median turnaround time of mNGS reporting was 1 day (range, 1–2 days). All patients received antiviral therapy, with some receiving adjunctive corticosteroids and/or intravenous immunoglobulin.

Short-term outcomes at discharge were generally favorable, and only one patient developed secondary autoimmune encephalitis.</p>Conclusions<p>HHV-6 and HHV-7 encephalitis in immunocompetent children share overlapping clinical characteristics and lack specific early laboratory or imaging features. CSF mNGS enabled rapid and unbiased detection of HHV-6 and HHV-7 sequences and provided complementary etiological information when interpreted together with clinical and ancillary findings.</p>