It may be necessary to accelerate water treatment procedures. Also, the source of contamination must be located and protective measures taken to avoid further contamination. Until recently, Americans have regularly suffered through epidemics of waterborne illness such as cholera and typhoid fever. Improvements in waste water disposal practices and development, protection, and treatment of water supplies have significantly reduced the incidence of the these diseases. In some cases, sewage and other wastes are dumped directly into rivers that are used by people downstream for drinking and washing.
Epidemiologists study the incidence, transmission, distribution, and control of disease.
With waterborne diseases, determining how the water supply was contaminated is critical to solving the problem. The case histories of affected patients and any associations among patients help epidemiologists solve the mysteries of disease. Procedure Warm up Ask students if they can identify the world's number one killer. Explain that thousands of children die each year from diarrhea. Tell students that diarrhea is caused by microorganisms such as bacteria, viruses, and protozoa.