|
What is E. coli?
E. coli is short for Escherichia coli. It is a species of bacteria naturally present in human and animal excrement, and is part of the "coliform" group of bacteria. This group of bacteria, and E. coli in particular, has been used as an indicator of the bacteriological safety of water since it was first isolated from faeces in the late 19th century.
E. coli is used as a water quality indicator because large numbers of the bacteria are always present in the feces of humans and other warm-blooded animals, but are not naturally found in water. Since these bacteria don’t live long in water once outside the intestine, their presence in water means there has been recent contamination through sewage discharges or other sources.
How does E. coli enter our water?
Water can be contaminated in a variety of ways. Main sources of E. coli are municipal sewage discharges or runoff from failing septic systems, animal feed operations, farms and faeces deposited in woodlands from warm blooded animals. In urban areas, the E. coli from the excrement of warm blooded animals (such as pets in a park or on the street) may be washed into creeks, rivers, streams, lakes, or groundwater during rainfalls or snow melts. The contamination in water is often highest immediately following a storm, because of the runoff. In addition, infected bathers can unknowingly contaminate water, or contamination can occur from boaters discharging wastes directly into the water. When these waters are used as sources of drinking water and the water is not treated or inadequately treated, E. coli may end up in drinking water.
How does E. coli affect human health?
There are hundreds of strains of E. coli. Most are harmless and live in the intestines of healthy humans and animals. Some, such as E. coli O157:H7, can cause severe illness. Infection often causes severe bloody diarrhoea, abdominal cramps, and possibly fever (these symptoms are common to a variety of diseases, and may be caused by sources other than contaminated drinking water). Young children, the elderly, and the chronically ill are at greater risk for severe symptoms. In some cases, infection can lead to kidney failure and possibly death.
How does E. coli affect the aquatic environment?
There is limited information on the effects of E. coli (or any faecal pathogens) on the aquatic community. There is growing concern, however, over impacts on ecosystems in Canada and around the world. For example, outbreaks of botulism produced by Clostridium botulinum have caused a large number of waterfowl to die in various locations across Canada. Fungus and virus strains are now being identified as a reason for declines in amphibian populations around the world, such as frogs in South America and tiger salamanders in Saskatchewan. Contamination from pathogens also leads to closing beaches for recreation, closing shellfish beds and the contamination of irrigation waters for agriculture.
What are the E. coli guidelines?
The Federal-Provincial-Territorial Committee on Drinking Water has published a guideline for the bacteriological quality of drinking water, which specifies that E. coli should not be present in drinking water.
What can individuals do to help?
To help avoid E. coli from reaching our water supply:
- Avoid going in the water if you have an open wound or an infection.
- Take limited amounts of food to beaches to avoid attracting animals and birds that leave droppings. Don't feed animals or birds, and securely close garbage bins.
- Pick up pet droppings and dispose of them hygienically.
- Avoid using fertilizers near recreational water.
- Ensure septic systems are operating properly.
- Practice pollution-free boating by disposing of human waste hygienically.
- Make sure livestock are maintained a safe distance away from drinking water sources. One best management practice is a buffer area between cattle and stream.
- Ensure that drinking wells are properly maintained and capped to avoid contamination.
- Encourage proper wastewater treatment by your municipality and local industries.
|
