Contaminated Water can be a Source of Disease and Death
Robert
1
and Mary Beth
2
Metcalf
1Professor Emeritus, Biological Sciences, California State University, Sacramento
2Clinical Professor Emeritus, Dept. of Pediatrics, U. of California, Davis, Medical School
Excerpt by Margo (editor)
A more extensive report can be found on:
“Water is Life”
is often stated, but the corollary to this is that contaminated water can be a source of disease and death. Although waterborne diseases have been almost eliminated in developed countries through efficient water treatment and sewage disposal, over a billion people in extreme poverty worldwide are still plagued with waterborne diseases, estimated to cause DAILY between four to six million cases of diarrhea and > 2,000 deaths. Yet this misery is preventable – kill the germs with chlorine or heat, and people don’t get sick.
Once it was understood that fecal contamination of water could be the source of disease-causing bacteria, the question arose about how to test water for fecal contamination. It was recognized that testing for all the known waterborne pathogens was impractical. Instead, a universal microbial indicator of fecal contamination was sought. By 1900, Escherichia coli was selected as the best microbial indicator of recent fecal contamination because of these properties: 1) E. coli was always present in the feces of humans and other mammals in large numbers, whether one is healthy or sick; 2) it doesn’t multiply when it leaves the body and enters water; 3) it slowly dies when shed in feces, but it survives in water at least as long as bacteria that cause typhoid fever, cholera, and dysentery; and 4) it is relatively easy to detect.
The presence of E. coli in drinking water; therefore, indicates recent fecal contamination, raising the possibility that disease-causing microbes may also be in the water. The World Health Organization (WHO) correlated levels of E. coli in drinking water with the risk of disease and the priority for action. Médecins Sans Frontiéres (MSF) correlated these levels for action in emergencies.
Challenges in Low-Income Countries
Water quality monitoring is often a missing factor in programs to improve access to safe drinking water in low-income countries, despite its importance from a public health standpoint. This is because standard tests using multiple tube fermentation or membrane filtration require specialized equipment and training and are not easily adapted to field testing. In addition, the linkage between water quality and disease is commonly not appreciated at the community and household level.
Public health problems arise in urban areas as a result of water supplies being intermittent or if coagulant / disinfectant supplies are missing. Rural areas often lack public support for providing and maintaining improved water sources. People must use contaminated local sources such as streams, ponds, rivers, or shallow wells.
Water quality testing must be a component where drinking water is involved. For low-income countries with limited resources, it is recommended they establish realistic, interim achievable standards.
