Few cases of complicated infections with Listeria monocytogenes (LM) have been reported to date in patients with multiple sclerosis (MS) treated with alemtuzumab. Primary prevention strategies may be suggested in such patients to avoid infections. However, these may be ineffective because patients may already be carriers of LM. We report herein a case of bloodstream infection due to LM in a 25-year-old woman with MS treated with alemtuzumab. We searched the UMC/WHO Vigibase system for all reported cases of LM in patients treated with alemtuzumab and found 29 cases overall up to 21 July 2019. We also performed a literature review of MS cases with LM on alemtuzumab, in order to evaluate epidemiology, clinical characteristics, and outcome of this complication. Since the published cases (N=8) were mainly reported in recent years but more cases were found in the UMC/WHO Vigibase system (although not necessarily in patients with MS), we hypothesize that this complication is more frequent than currently believed and may become even more important in the future. Therefore, it is worth reaching a consensus on appropriate algorithms to stratify individuals by risk so as to implement targeted prevention strategies (whether primary or secondary).