Influenza B-associated encephalitis with rapid improvement with oseltamivir

A 25-year-old female veterinarian presented with 1-week of flu-like symptoms followed by progressive encephalopathy. She was originally from Nicaragua and had been in the USA for 4 months. In the emergency department, she was confused and non-verbal with meningismus and facial myoclonus, but with an otherwise non-focal neurological exam. MRI brain abnormalities were consistent with viral encephalitides. Influenza B was detected via nasopharyngeal swab PCR. Mental status improved rapidly with oseltamivir. In such presentations, especially during flu season, influenza encephalitis must be considered, to facilitate early recognition of this entity and allow for targeted treatment.