Does natalizumab treatment increase the risk of herpes simplex encephalitis in multiple sclerosis? Case and discussion.

This report presents the 4th documented case worldwide of herpes simplex encephalitis in multiple sclerosis (MS) patients treated with natalizumab and the first case in the UK. Natalizumab is licensed for relapsing remitting multiple sclerosis in patients with high disease activity despite treatment with interferon-beta and patients with rapidly evolving severe, multiple sclerosis. Natalizumab is a monoclonal antibody targeted against alpha-4 integrin.