Epstein-Barr virus encephalitis in an immunocompetent elderly patient: A case report.

We report a case of severe Epstein-Barr virus (EBV) encephalitis in a 79-year-old immunocompetent patient. The patient initially presented without overt infectious manifestations, complaining solely of weakness in both lower limbs for one week. Physical examination revealed tremors in the upper limbs and tachypnea. Symptoms progressed rapidly after admission, with the subsequent development of headache and fever. Based on the clinical presentation, viral encephalitis was suspected. Cerebrospinal fluid analysis via next-generation sequencing (NGS) confirmed the diagnosis of EBV encephalitis. Despite treatment with ganciclovir, the patient's condition deteriorated, leading to respiratory arrest that required tracheal intubation and mechanical ventilation. The patient's status improved significantly following a combination therapy of intravenous immunoglobulin and steroid pulse therapy, ultimately achieving clinical recovery and successful discharge. This case highlights that EBV encephalitis can occur in immunocompetent elderly individuals, and early-stage symptoms may be atypical. When conventional antiviral therapy proves ineffective, immunoglobulins and corticosteroids should be considered as therapeutic options.