Leprosy (Hansen’S Disease)
The microbiological history of leprosy may be divided into three periods: the first before A. Hansen, the second between A. Hansen and C. C. Shepard, and the third after C. C. Shepard. All efforts to cultivate the bacillus in vitro failed and the leprosy bacillus joined the group of in vitro uncultivable disease agents, where it has remained up to this writing. In 1960 Shepard developed a technique to study the limited multiplication of Mycobacterium leprae in the mouse foot pad. This formed the basis for further studies, mainly in the field of chemotherapy. The mycolic acid pattern in M. leprae is characteristic for the species, and ketomycolates are present; there are no methoxymycolates. Tuberculostearic acid is a major component. The lepromin test has little diagnostic reliability since positive tests may be seen in normal individuals living in nonendemic countries and in those who have never been exposed.