Limbic Encephalitis Associated with Human Herpesvirus-7 Infection in an Immunocompetent Adolescent

Despite the ubiquitous nature of human herpesvirus-7 (HHV-7) infection, its clinical significance in the central nervous system (CNS) is poorly understood. However, the related human herpesvirus-6 (HHV-6), which has remarkable genomic similarity to HHV-7, is linked to encephalitis. We present the case of a 17-year-old immunocompetent male with remote history of seizure who arrived in status epilepticus. Upon resolution, he required hospitalization for worsening encephalopathy. Electroencephalogram (EEG) revealed bilateral temporal lobe dysfunction and magnetic resonance imaging (MRI) showed increased signaling in bilateral medial temporal lobes with hippocampal microhemorrhages. Empiric intravenous (IV) acyclovir was initiated despite initially negative cerebrospinal fluid (CSF) studies due to concern for herpes simplex virus (HSV) encephalitis. The patient improved and was discharged on hospital day 13 (HD13). After discharge, a human metagenomics CSF panel resulted positive only for HHV-7, making a case for possible etiology and empiric treatment of HHV-7 despite delayed CSF and serum studies.