Borrelia miyamotoi meningoradiculitis complicating ocrelizumab treatment for multiple sclerosis: A report of three cases.

Ocrelizumab is an anti-CD20 monoclonal antibody that is highly effective in multiple sclerosis (MS) but is associated with an increased risk of opportunistic infections that may be difficult to diagnose. We report three MS patients treated with ocrelizumab who developed severe meningoradiculitis. Routine investigations failed to identify any pathogen, whereas metatranscriptomic analysis of cerebrospinal fluid (CSF) detected Borrelia miyamotoi RNA. All patients improved after appropriate antibiotic therapy. B. miyamotoi should be considered in anti-CD20-treated MS patients presenting with meningoradiculitis, and CSF metatranscriptomics should be used to investigate undiagnosed central or peripheral nervous system infections, particularly in immunocompromised individuals. Ocrelizumab is a highly effective treatment widely used in MS but has been associated with an increased risk of infection. We report three cases of B. miyamotoi infections in patients receiving ocrelizumab in which routine laboratory tests failed to detect the pathogen.