What is Etiology?

Mary McMahon
Mary McMahon

Etiology is the study of causes. A number of disciplines utilize etiology, ranging from anthropology to physics, but it is most commonly associated with the medical world. In medical research, understanding the origins and causes of medical conditions is extremely important, because etiology can be used to provide clues into methods of treatment which might be effective.


This word comes from the Greek aitia, which means “cause.” Outside of the United States, it is usually spelled as “aetiology,” rather than “etiology,” and sometimes as “aitiology.” These alternate spellings are primarily a matter of personal preference; people who are familiar with one spelling can easily understand an alternate spelling, especially in context. This word has been used in English since 1555, borrowed from the Greek.

In the case of an individual patient, understanding etiology can be extremely important, as it may provide a vital piece of the puzzle when it comes to treating a condition. When a cause cannot be determined, the disease is said to be “idiopathic,” meaning that it has no known etiology. Idiopathic conditions can be very frustrating for physicians and patients alike, as the lack of an etiology can make it difficult to pin down the precise nature of a disease.

Medical researchers, especially those who respond to epidemics, also rely heavily on etiology. When a disease outbreak occurs, the more quickly the etiology can be determined, the more quickly it can be brought under control, because the factor which creates the disease can be eliminated, controlled, or avoided. For instance, when a large bunch of cases of food borne illness are reported, a database is constructed to compare the patients, looking for the common denominator so that a batch of tainted food can be recalled and destroyed.

The study of etiology is quite ancient. Ancient China, Greece, and Rome all had individuals who examined the nature of disease, although many of them drew erroneous conclusions. Many people date the serious study of etiology to the Muslim world, where physicians first started to draw conclusions about the spread of epidemics, and the need for controlled clean conditions in outbreaks to prevent the spread of disease.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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