Shigellosis, a highly contagious diarrheal disease, is caused by Shigella bacteria circulating in industrializing countries but also in industrialized countries. Scientists from the French National Reference Center for Escherichia coli, Shigella and Salmonella at the Institut Pasteur who have been monitoring Shigella in France for several years have detected the emergence of extensively drug-resistant (XDR) strains of Shigella sonnei.