Public health service originated in the minds of doctors who recognized the need of the community for this important branch of medicine. Jenner and Waterhouse were practitioners of medicine as well as the founders of preventive medicine and the forerunners of modern public health service. Oliver Wendell Holmes was likewise an ardent champion of preventive medicine as well as a practitioner of the medical art. Austin Flint, the eminent physician and cardiologist, was one of the earliest epidemiologists; he conclusively established the source of an epidemic of typhoid in New York State when there was error and much confusion of thought in regard to the etiology.
The practitioner of medicine by tradition is interested in public health problems. His enthusiasm for and cooperation in public health programs has varied from time to time. By training, the physician is taught to individualize his knowledge to a great degree. However, it is