Natural history of disease

Natural history of disease refers to a description of the uninterrupted progression of the disease in an individual from the moment of exposure to the causal agents until recovery or death. Bhopal (2002) argues that knowledge of the natural history of disease ranks alongside causal understanding in importance for prevention and control of disease. Natural history of disease is one of the major elements of descriptive epidemiology.

The “iceberg phenomenon” is a metaphor emphasizing that for virtually every health problem the number of known cases of disease is outweighed by those that remain undiscovered, much as the unseen part of an iceberg is much larger than the part that is visible above the water. The iceberg phenomenon thwarts attempts to assess the burden of disease and the need for services, as well as the selection of representative cases for study. This leads to what has been called the “clinician’s fallacy” in which an inaccurate view of the nature and causes of a disease results from studying the minority of cases of the disease that are seen in clinical treatment (Morris, 1975; Duncan, 1988).