Detection of uncommon diseases and their affectations

The environment in which people live has an enormous influence on health, the extent to which the health situation in a country can be improved by modifications to its environment is difficult to quantify. Providing adequate quantities of food and water of acceptable quality and breaking the oral-fecal chain are essential to reducing gastrointestinal diseases. These had already declined significantly in most of Europe and North America before the introduction of certain therapeutic drugs and oral rehydration therapy. Similarly, while immunization and the use of modern drugs have contributed to the dramatic decline in mortality from infectious respiratory diseases, the reduction of overcrowding, improved overall housing and nutrition have played the greatest role. The environment has also played an indirect role in reducing mortality from cardiovascular disease and many other chronic diseases, including liver cirrhosis, gastric ulcers, diabetes, and chronic obstructive pulmonary disease among others.