Agostino Bassi, sometimes called de Lodi (25 September 1773 – 8 February 1856), was an Italian entomologist. He preceded Louis Pasteur in the discovery that microorganisms can be the cause of disease (the germ theory of disease). He discovered that the muscardine disease of silkworms was caused by a living, very small, parasitic organism, a fungus that would be named eventually Beauveria bassiana in his honor. In 1844, he stated the idea that not only animal (insect), but also human diseases are caused by other living microorganisms; for example, measles, syphilis, and the plague.