Herpes Simplex Virus Type 1 Encephalitis in a Six-Year-Old Girl: A Case Report From Latin America.

Herpes simplex virus type 1 (HSV-1) encephalitis is a severe neurological condition that can cause significant morbidity and mortality, particularly in pediatric patients. Prompt recognition and treatment are crucial to preventing long-term complications. This case report aims to highlight the diagnostic challenges and importance of early antiviral therapy in pediatric HSV-1 encephalitis. We describe a six-year-old girl admitted with fever, headache, vomiting, progressive somnolence, and a prolonged generalized tonic-clonic seizure. Upon admission, she exhibited oral aphthae, somnolence, and mild hyperkalemia. Brain magnetic resonance imaging revealed unilateral hyperintensity in the right mesial temporal lobe involving the hippocampus and parahippocampal gyrus. Electroencephalography demonstrated diffuse cortical dysfunction without epileptiform discharges. Cerebrospinal fluid polymerase chain reaction confirmed HSV-1 infection, while other inflammatory parameters remained within normal limits. Empirical intravenous acyclovir was initiated immediately and continued for 21 days, with favorable tolerance and neurological improvement. At the time of last follow-up, the patient remained clinically stable, with plans for long-term neurological monitoring. This case underscores the importance of early diagnosis and comprehensive management, including neuroimaging, electroencephalography, and cerebrospinal fluid analysis, to guide timely therapeutic decisions and prevent irreversible neurological damage in pediatric patients.