Acute respiratory distress syndrome following alemtuzumab therapy for relapsing multiple sclerosis.

We present the case of a 54 year old woman with known relapsing-remitting multiple sclerosis who presented with acute respiratory deterioration five weeks after a first course of alemtuzumab. Imaging showed bilateral ground glass changes and extensive investigations confirmed chest infection with dual pathogens - Pneumocystis jirovecii and Cytomegalovirus. She responded to standard anti-PJP and CMV therapy and was discharged on oral prophylaxis. Opportunistic infections in the weeks immediately following alemtuzumab therapy remain an uncommon complication but one that requires clinical vigilance, careful monitoring and appropriate prophylactic therapy.