[Perspective] Leprosy in red squirrels

In 1873, the Norwegian doctor Armauer Hansen helped to lay the foundations of modern microbiology when he discovered that leprosy was an infectious disease, not an inherited condition. However, his attempts to cultivate the rod-shaped bacilli that he had observed in microscopic studies of tissues from leprosy patients were unsuccessful, emphasizing the unique growth requirements of these bacilli. Even today, Mycobacterium leprae, the causative organism of leprosy, cannot be grown on culture medi