Human herpes virus-7-related severe encephalitis diagnosed using mNGS in immunocompetent pediatric patients

Abstract

Background: This study sought to describe the clinical characteristics, examination results, and prognoses of immunocompetent children with human herpes virus 7 (HHV-7)-related severe encephalitis.

Methods: Twelve immunocompetent children with severe HHV-7-related encephalitis were included, all of whom had HHV-7 DNA ( +) detected in the cerebrospinal fluid via metagenomic next-generation sequencing (mNGS) and were followed up for > 6 months.

Results: The cohort comprised 75% males, with a median age of 4.5 years; all patients presented with fever and altered consciousness and required PICU admission for severe neurological symptoms. Two patients developed encephalitis sequelae and epilepsy. Abnormal electroencephalography and brain magnetic resonance imaging findings were observed in 90.9% (10/11) and 72.7% (8/11) of the patients, respectively. Five patients required ventilator support due to central respiratory failure (four invasive and one noninvasive). One patient underwent plasma exchange, while another received continuous renal replacement therapy. All patients were treated with acyclovir and immunomodulatory therapy. Four patients had poor prognoses, including one 9-year-old male who died and one 9-year-old female who was diagnosed with febrile infection-related epilepsy syndrome and remained in a coma with a Modified Rankin Scale score of 5 at the 6-month follow-up.

Conclusions: Older immunocompetent children with severe HHV-7-related encephalitis have poor prognosis and low survival rates, both of which may be improved via empiric acyclovir administration combined with immunosuppressive therapy.

Keywords: Children; Encephalitis; Human herpes virus-7; Immunocompetent; Metagenomic next-generation sequencing.

Fig. 1

Brain MRI findings in patients with HHV-7-related encephalitis. Patient 1: A 6-year-old boy with fever and altered consciousness (MRI performed 3 d after admission; A–C). A: DWI reveals multiple patchy diffusion-restricted hyperintense signals in both cerebral hemispheres. B, C: T1- and T2-weighted images demonstrate diffuse, mass-like patches with slightly prolonged T1 and T2 signal intensities bilaterally. Patient 2: A 4-year-old boy presenting with status epilepticus (MRI performed 3 d after admission; D–F). D: DWI shows a punctate diffusion-restricted hypointense signal near the posterior horns of bilateral lateral ventricles. E, F: T1- and T2-weighted sequences reveal small patches of prolonged signal intensity near the posterior horns; FLAIR imaging exhibits subtle hyperintensity. Mild T2 hyperintensity is noted in the bilateral basal ganglia. Patient 5: A 9-year-old girl with status epilepticus (MRI performed 30 d after admission; G–I). G: Axial FLAIR sequence shows no apparent abnormalities. H, I: T1- and T2-weighted images depict bilateral subcortical swelling with prolonged signal intensities. DWI: Diffusion-weighted imaging