Varicella Zoster Virus as a trigger for Multiple Sclerosis

Multiple sclerosis (MS) is an immune-mediated demyelinating disorder of the central nervous system, with environmental factors potentially triggering disease in susceptible individuals. Although a link between varicella-zoster virus (VZV) and MS onset has been suggested, the association remains inconclusive. We report a previously healthy 17-year-old girl who presented with mild headache and a three-day history of vesicular lesions consistent with varicella. Initial neurological examination and brain MRI were normal. Due to persistent headache and development of hand numbness, follow-up brain and spinal MRI two months later revealed multiple demyelinating lesions in the periventricular and pericallosal white matter, optic nerve, and cervical and thoracic spinal cord, with gadolinium enhancement. Cerebrospinal fluid analysis demonstrated type 2 oligoclonal bands and elevated IgG index (0.67). Serum VZV serology showed positive IgG and elevated IgM (42.6 AU/mL), consistent with recent infection or reactivation. The patient fulfilled the revised 2024 McDonald criteria and was diagnosed with MS. She received intravenous methylprednisolone, achieved complete clinical recovery, and was started on dimethyl fumarate. This case supports a potential role of VZV as a trigger for MS onset.