Epidemiology (Greek epi = upon, among; demos = people, district; logos = word, discourse), defined literally, is the study of epidemics in humans. It is a broad field of study that uses principles of investigation, medicine, and biostatistical methodology. There are many different types of epidemiology, just as there are many different specialities within medicine. Although the recognition of epidemiology as its own field of study is fairly recent, epidemiology has been the foundation of public health and medicine throughout history.

Epidemiology in its broadest sense is the study of disease patterns in human populations. Its methods can also be used to study diseases in animal populations, though in this instance it would be called epizoology. Epidemiologists work in variety of settings. Some epidemiologists work "in the field" meaning they are at the forefront of combatting disease outbreaks all over the world. Typically, field epidemiologists are working to determine the cause of a infectious disease outbreak or epidemic. Epidemiologists also study so-called chronic diseases such as heart disease, obesity, diabetes, and cancer. Clinical trials that test new treatments and medications also require the expertise of epidemiologists to be conducted properly.

By studying disease patterns in populations through the use of basic demographics or complex genetic and environmental influences, epidemiology can identify potential risk factors for disease and help determine ways of prevention (as in the case of HIV/AIDS).

The advancement of modern medicine relies upon sound epidemiological methods.

History of epidemiology

Dr. John Snow is famous for the suppression of an 1854 outbreak of cholera in London's Soho district. He identified the cause of the outbreak as a public water pump in Broad Street, and had the handle removed, thus ending the outbreak.

This was a major event in the history of public health, and can be regarded as the founding event of the science of epidemiology.

In the early 20th century mathematical methods were introduced into epidemiology by Ronald Ross, Anderson Gray McKendrick and others.

Another breakthrough was the 1956 publication of results of the British doctors study, which lent statistical support to the suspicion that tobacco smoking was linked to lung cancer.

See also

• prevalence
• incidence epidemiology
• Important publications in epidemiology

External links

• Epidemiology (http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.chapter.631). Chapter 9 from Medical Microbiology 4th ed textbook at US National Center for Biotechnology Information. Plain format at University of Texas Medical Branch at Galveston (http://gsbs.utmb.edu/microbook/)
• Epimonitor (http://www.epimonitor.net/index.htm) has a comprehensive list of links to associations, agencies, bulletins, etc.
• Epidemiology for the Uninitiated (http://bmj.bmjjournals.com/epidem/epid.html) On line text, with easy explanations.
• North Carolina Center for Public Health Preparedness Training (http://www.sph.unc.edu/nccphp/training/) On line training classes for epidemiology and related topics.