who was responsible for establishing the idea that microorganisms play a role in disease
Germ theory of disease The germ theory was proposed by Girolamo Fracastoro in 1546, and expanded upon by Marcus von Plenciz in 1762. Such views were held in disdain, however, and Galen's miasma theory remained dominant among scientists and doctors. The nature of this doctrine prevented them from understanding how diseases actually progressed, with predictable consequences. By the early nineteenth century, smallpox vaccination was commonplace in Europe, though doctors were unaware of how it worked or how to extend the principle to other diseases. Similar treatments had been prevalent in India from just before 1000 A.D.[2] [N 1] A transitional period began in the late 1850s as the work of Louis Pasteur and Robert Koch provided convincing evidence; by 1880, the miasma theory was struggling to compete with the germ theory of disease. Eventually, a "golden era" of bacteriology ensued, during which the theory quickly led to the identification of the actual organisms that cause many diseases.[3][4] Viruses were discovered in the 1890s.
Sociology of health and illness Health, or lack of health, was once merely attributed to biological or natural conditions. Sociologists have demonstrated that the spread of diseases is heavily influenced by the socioeconomic status of individuals, ethnic traditions or beliefs, and other cultural factors.[3] Where medical research might gather statistics on a disease, a sociological perspective on an illness would provide insight on what external factors caused the demographics who contracted the disease to become ill.[3]