Herpes Simplex Virus Type 2 Encephalitis in an Immunocompetent Adult: A Diagnostic Challenge

Abstract

Herpetic encephalitis is the most common cause of fatal sporadic encephalitis. Beyond the neonatal period, herpes simplex virus type 1 (HSV-1) is the etiologic agent in nearly all cases, with < 10% of cases attributable to HSV-2. Nevertheless, neurological infections caused by HSV-2 are responsible for significant morbidity and mortality. Therefore, it must be diagnosed and treated at an early stage. It is classically characterized by a triad of fever, headache, and behavioral changes. The association of these symptoms, laboratory tests, and imaging is fundamental for the early diagnosis and immediate treatment of this pathology to prevent its progression from being fatal. We report a rare case of HSV-2 encephalitis in a previously healthy 61-year-old man, free of genital lesions, who presented with altered mental status, fever, altered cerebrospinal fluid (CFS) with lymphocytic pleocytosis, normal brain imaging, and an initially negative CFS polymerase chain reaction for HSV-1 and HSV-2.