You were possible taught in elementary school that Marco Polo went to China in the 1200s to get spices; but did you remember that these spices were needed to improve the smell and taste of spoiled foods? The Roman baths had indoor plumbing in the 1200s, but volcanoes destroyed many of the baths; and the people migrated rapidly to Greece. In the rush to build new civilizations, and during the explosive population increases, very little attention was given to water quality and treatment. As the result of eating food and drinking water contaminated with microbes, many outbreaks and epidemics occurred.

How do micro-organisms get into food and water? We know that the air and soil contain many different types of microbes; so soil and air are two major sources of microbes that contaminate food and water. Animals like rodents and flies, as wll as plants and cattle in streams, may add microbes to the food and water. If the animals are diseased, the danger of disease outbreaks in humans may be increased. During the handling of food, and possibly water, our techniques may not be as aseptic as desired; and contamination may occur. Foods contain their normal flora (microbes) and sometimes we intentionally introduce microbes into food to initiate fermentation. It is certainly easy to visualize that there are numerous sources of microbes in food and water. With our expectation that a great variety of food choices be available every day and our desire to have little turnover time between use and reuse of water, it is extremely important that we understand the basic principles of microbiology.