Why armadillos are crucial to ending leprosy: Scientists have been trying to understand leprosy and develop a treatment for it for more than three millennia, and some say it's possible that humans first transmitted Mycobacterium leprae to armadillos, not the other way around. A new multidrug therapy stops the disease's progression but doesn't prevent new cases, and because M. leprae can't be grown in a lab, scientists work with armadillos to learn more about leprosy and design new diagnostics and treatments.