Strains of Mycobacterium leprae—the main bacterium behind leprosy*—are hypermutating and becoming extremely drug resistant. Researchers made the alarming discovery in a survey of 154 M. leprae genomes collected from 25 countries. The survey, published recently in Nature Communications, offers a rare genetic glimpse of the ancient, yet cryptic, bacterium, which still manages to cause 200,000 new cases worldwide each year.