A Case of Varicella Zoster Virus Encephalitis – A Rare but Often Fatal Cause of Encephalitis

Abstract

Background: Primary infection with varicella zoster virus (VZV) causes varicella (chickenpox), while herpes zoster (shingles) is a secondary infection that occurs when latent VZV is reactivated. Both primary and secondary VZV infections can cause central nervous system manifestations, including encephalitis, which is rare and often fatal. Case Presentation: A 66-year-old woman with history of rheumatoid arthritis, psoriasis, and coronary artery disease presented to our hospital with sudden-onset altered mental status. She was found naked, confused, and covered in feces and urine at home. At presentation, she was afebrile, tachycardiac (106 bpm), tachypneic (24 breaths/min), saturating 97% breathing ambient air. Labs were unremarkable. Non-contrast head CT revealed disproportionately enlarged ventricles and temporal lobe volume loss. Brain MRI confirmed ventriculomegaly. Blood cultures were drawn, and IV vancomycin, ceftriaxone, and ampicillin were started empirically. Initial blood cultures were negative. On Day 3, lumbar puncture with cerebrospinal fluid (CSF) analysis showed elevated WBC (1,077 cells/mcL) with 97% lymphocytes, low glucose (21 mg/dL) and elevated protein (298 mg/dL). CSF viral PCR panel was positive for VZV, necessitating initiation of IV acyclovir. Given no significant improvement despite treatment, lumbar puncture was repeated on Day 8, with similar findings as the initial CSF analysis. Ampicillin was discontinued because repeated blood cultures and CSF analysis were negative for Listeria. By Day 17, she had completed a 14-day course of IV acyclovir but remained febrile and confused. The patient’s family decided to transition her to comfort care measures, and she expired on Day 23. Discussion: Nervous system manifestations of VZV include meningitis, encephalitis, cerebellar ataxia, vasculopathy, and myelopathy. Unlike encephalitis caused by herpes simplex virus type-1 and enteroviruses, VZV encephalitis is uncommon, occurring in one out of every 33,000 to 50,000 cases of VZV infection. VZV encephalitis is associated with intense inflammation, and often has an acute presentation. Studies report higher median CSF protein levels and higher CSF lymphocytosis in VZV encephalitis compared to enterovirus encephalitis. Even with appropriate treatment, VZV encephalitis is almost 100% fatal in immunocompromised hosts. A high index of suspicion and early initiation of appropriate treatment for VZV encephalitis is essential, especially in immunocompromised hosts.