Norwegian doctors, Daniel Cornelius Daniellsen and Carl Wilhelm Boeck, described the broad clinical features of leprosy in 1847. The disease was thought to be hereditary since family members were often afflicted. Inspired by Louis Pasteur’s new “germ theory,” Daniellsen’s son in law, Armauer Hansen, astounded the medical world in 1874 by describing the small, rod-shaped organisms that cause leprosy, the first demonstration of bacteria as an agent of human disease. In the intervening 130+ years, M. leprae, the leprosy bacillus, has failed to yield its secrets to investigators. M. leprae has yet to be cultured in the laboratory. Leprosy is the Cousin of Tuberculosis: The bacteria are microscopically indistinguishable Tuberculosis 15 million cases worldwide 1.6 million deaths (2005) 10-15% of infected develop TB Leprosy Less than 1 million cases worldwide Death extremely rare 95% of population resistant Obstacles in Leprosy Research The disease process in humans is slow and chronic M. leprae grows very slowly and cannot be cultured Doubling time of bacilli is 13 days (E. coli doubles every 20 minutes) Long incubation period before symptoms appear in humans Difficult to track the source and route of infection No diagnostic test for pre-clinical disease Overcoming Obstacles: Animal Models in Research Conventional mouse Moderate growth of bacilli in cooler body parts, such as the hind foot pads Growth is slow, taking one year for an experiment Athymic (nude) mouse Billions of bacilli grow in the foot pads; they have no T-cells to fight infection Experiments take about one year Nine-banded armadillo Systemic infection since core body temperature is 33ºC Billions of M. Leprae per gram of liver, spleen, lymph node tissue Experiments take one to two years    The Armadillo is More than a Factory for Producing M. leprae The armadillo mimics many aspects of human leprosy, including nerve damage that causes loss of sensation in the feet resulting in plantar inflammation and injury. Studies are now underway to produce the relevant immunological and molecular reagents to exploit this unique animal model of leprosy.      Next Page