In this case report the authors describe a case of non-fatal herpes simplex virus encephalitis (HSE) in a subject on natalizumab for MS. A 36-year-old woman, previously treated with immunomodulatory and immunosuppressive drugs for MS, developed acute encephalitis after 6 monthly natalizumab infusions. Brain imaging demonstrated bi-temporal lesions typical of HSE. Herpes simplex virus type-1 DNA was detected in cerebrospinal fluid (diagnostic test). The patient improved gradually after a 21-day course of intravenous acyclovir, but neuropsychiatric changes remained 5 months later (poor prognosis). This non-fatal case of HSE and other reported cases of herpes infections provide evidence of an increased risk with natalizumab and point to the need for clinicians to maintain awareness.
"I couldn't agree more with the conclusion; we all need to aware of that PML is not the only infectious disease complication that can occur whilst on Natalizumab. Although HSE is rare more cases will appear over time. Please remain vigilant to any new symptoms whilst on treatment."