Cause (medicine)
Cause, also known as etiology () and aetiology, is the reason or origination of something. The word etiology is derived from the Greek , aitiologia, "giving a reason for" (, aitia, "cause"; and , -logia). Description In medicine, etiology refers to the cause or causes of diseases or pathologies. Where no etiology can be ascertained, the disorder is said to be idiopathic. Traditional accounts of the causes of disease may point to the "evil eye". The Ancient Roman scholar Marcus Terentius Varro put forward early ideas about microorganisms in a 1st-century BC book titled On Agriculture. Medieval thinking on the etiology of disease showed the influence of Galen and of Hippocrates. Medieval European doctors generally held the view that disease was related to the air and adopted a miasmatic approach to disease etiology. Etiological discovery in medicine has a history in Robert Koch's demonstration that species of the pathogenic bacteria Mycobacterium tuberculosis causes the disease tuberculosis; Bacillus anthracis causes anthrax, and Vibrio cholerae causes cholera. This line of thinking and evidence is summarized in Koch's postulates. But proof of causation in infectious diseases is limited to individual cases that provide experimental evidence of etiology. In epidemiology, several lines of evidence