“As a geographer I am very biased. It is my belief that until we can convincingly establish why a particular disease is common in some regions and very rare or absent from others, we have achieved very little of intellectual significance.” Dr. Harold D. Foster
This means that what we are exposed to in the environment, what we eat and drink, the nature of our lifestyles and the provision of medical care varies from place to place, which correlates directly to the probability of developing, or dying from, a particular disease.1
This can be seen by looking at geographic maps showing the incidence and death rate of a disease across the world – every disease has a global geographic pattern. So in some areas of the world there are high incidences of, for example, HIV/AIDS, as in sub-Saharan Africa and other areas of the world there are very low incidences of HIV/AIDS, as in Finland, Senegal and Bolivia (See our HIV/AIDS pages for more information).
How can we use geographic disease patterns to find the environmental causes of diseases?
Medical Geography can also illustrate which factors are more dominant in the underlying causes of certain diseases. In some diseases, for instance, Dr. Foster used this approach to show how geography can be more important than genetics in determining whether individuals will develop a disease. He showed that although certain genetic changes may predispose a person to a disease, the overriding factor that leads to disease is through the negative impact of a specific lifestyle and/or environmental factors.2 He described it as: “Genes loading the gun, and the environment pulling the trigger.”
In summary, Medical Geography utilizes a wide variety of medical data to look for strong correlations between diseases and environmental factors. Correlations, however strong, do not prove the cause of a disease, however, they provide another piece to the puzzle and once studied can be used to generate new hypotheses (information) which can be tested further.
- Foster, HD. Health, Disease and the Environment. Belhaven Press, 1992.
- Foster, HD. What Really Causes Alzheimer's Disease. Trafford Publishing, 2004.