Abstract Introduction Human herpesvirus 6 (HHV-6) is a member of the Roseolovirus genus within the Herpesviridae family. It is classically recognized as the causative agent of Roseola infantum, a benign self-limiting infection of early childhood. However, in recent years, HHV-6 has increasingly been implicated in severe central nervous system (CNS) infections, particularly encephalitis, most often in immunocompromised hosts due to viral reactivation. Reports in immunocompetent adults remain rare. Case Presentation A 65-year-old male with a past medical history of hypertension presented with fever, generalized weakness, confusion, and calf muscle pain. On admission, his vital signs were: temperature 38.2 °C, blood pressure 94/67 mmHg, heart rate 108 beats per minute, and SpO2 98% on room air. According to his roommates, he had experienced frequent falls and progressive confusion for several days.Initial laboratory evaluation revealed: hemoglobin 12.5 g/dL, platelet count 60 × 10³/µL, sodium 128 mmol/L, and creatine kinase (CK) 18,140 U/L. Other values were unremarkable.During hospitalization, the patient developed seizures, treated with antiepileptic medications. Electroencephalogram (EEG) and computed tomography (CT) of the head were unremarkable. Brain MRI showed no acute structural abnormalities or enhancement.A lumbar puncture demonstrated 111 nucleated cells, 90,000 red blood cells, glucose 51 mg/dL, and protein 110 mg/dL. Broad-spectrum antibiotics were initiated for presumed meningitis. CSF was negative for Gram stain and culture, as well as PCR testing for herpes simplex virus, varicella zoster virus, and cytomegalovirus. However, PCR was positive for HHV-6 with a high viral load. HIV and syphilis testing were negative, and CD3/CD4 counts were within normal limits.The patient was started on intravenous ganciclovir in addition to anticonvulsant therapy with lamotrigine and oxcarbazepine. After one week of therapy, he demonstrated significant improvement and was discharged in stable condition. Follow-up serology revealed elevated HHV-6 IgG titers. Discussion HHV-6 is a common childhood pathogen, with most adults showing prior exposure. While reactivation typically affects immunocompromised patients, encephalitis in immunocompetent adults is rare and diagnostically challenging, often mimicking more common viral CNS infections.Current treatment guidance is largely derived from post-transplant populations, where intravenous ganciclovir and foscarnet have demonstrated efficacy. In immunocompetent patients, therapy must be individualized, but early diagnosis via CSF PCR and prompt initiation of antivirals are critical to improving outcomes.This case emphasizes the need to consider HHV-6 in unexplained meningoencephalitis, regardless of immune status, and highlights the role of PCR testing in guiding timely, effective management. This abstract is funded by: none
Cheema et al. (Fri,) studied this question.