The germ theory of disease, one of the great accomplishments of science, was not established for two centuries after Anton van Leeuenhoek in 1674 saw microscopic, motile “animalcules” in stagnant pond water. These were relatively large single-celled and multicellular organisms. Actual observation of bacteria was beyond the capacity of the primitive microscopes of the time. The idea that such living organisms could be the cause of disease seems to have been first put forth by Carl von Linne (1707-1778) of taxonomy fame, and a few years later in 1765 more specifically by the Finnish physician Isaac Uddman {1733-1781}. In his doctoral dissertation to the Swedish Academy in 1765, Uddman speculated that leprosy was caused by specific living agents, animalcules smaller than those already seen with the microscope. This flash of insight was not followed up and Uddman’s name is practically unknown in the history of medicine. In 1873, Gerhard Hansen incriminated Mycobacterium leprae as the cause of leprosy, one of the first instances of the naming of a specific bacterium as the cause of a specific disease.

REFERENCE: Demaitre, L: Leprosy in Premodern Medicine, A Malady of the Whole Body. 2007. The Johns Hopkins University Press. Baltimore.

Submitted by Ron Fishman MD from the Cogan Ophthalmic History Society.