A 32-year-old woman presents with a 3-day history of fever, headache, and mild neck stiffness. She denies photophobia. On examination, temperature is 38.2°C, neck stiffness is mild, and Kernig sign is negative. Fundoscopy is normal. Non-contrast CT head is normal. Lumbar puncture shows: WBC 180/μL (90% lymphocytes), protein 65 mg/dL, glucose 48 mg/dL (serum glucose 110 mg/dL), Gram stain negative, culture negative. PCR for enterovirus is positive. What is the most appropriate next step in management?