The University of Alabama at Birmingham explains Epidemiology and Public Health. It states
“Public Health is a blend of sciences, skills and convictions that is focused on the preservation and improvement of the health of all people through preventive (rather than curative) measures.
Epidemiology is considered a basic science of public health. Epidemiology is: a) a quantitative discipline built on a working knowledge of probability, statistics, and sound research methods; b) a method of causal reasoning based on developing and testing hypotheses pertaining to occurrence and prevention of morbidity and mortality; and c) a tool for public health action to promote and protect the public’s health based on science, causal reasoning, and a dose of practical common sense (1).
The word epidemiology comes from the Greek words epi, meaning “on or upon,” demos, meaning “people,” and logos, meaning “the study of.” Many definitions have been proposed; here are two that capture the underlying principles and the public health spirit of epidemiology:”
Read more here : http://www.soph.uab.edu/epi/academics/studenthandbook/what