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Quick Facts
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Did you know? Because E. coli is closely linked to the presence of feces, it was identified as an indicator of fecal contamination and is now the most widely used target for determining the safety of drinking water and food supplies worldwide. |
Background
E. coli, aka Escherichia coli, is a bacterium found in the feces of all warm-blooded animals. First discovered by Theodor Escherich in 1885, E. coli is part of the normal gut flora and benefits humans by producing vitamin K and competing with other pathogenic bacteria, preventing their establishment in the intestine. Most strains of E. coli are completely harmless and –assuming warm bloodedness– you are constantly exposed to the bacteria.
However, several strains of E. coli are capable of causing mild to serious and sometimes fatal, disease. These are known as enterotoxigenic (ETEC), enteropathogenic (EPEC), or enterohemorrhagic (EHEC) strains. EHEC strains of E. coli cause gastroenteritis with profuse watery diarrhea accompanied by nausea, abdominal cramps and vomiting. This bacterium is a common cause of travelers’ diarrhea. EPEC strains are similar to ETEC isolates but contain toxins that are capable of initiating severe disease. EHEC E. coli almost always belong to the single serological type 0157:H7. This strain generates a potent group of toxins that produce bloody diarrhea which can be fatal—especially for children and the elderly.
E. coli, aka Escherichia coli, is a bacterium found in the feces of all warm-blooded animals. First discovered by Theodor Escherich in 1885, E. coli is part of the normal gut flora and benefits humans by producing vitamin K and competing with other pathogenic bacteria, preventing their establishment in the intestine. Most strains of E. coli are completely harmless and –assuming warm bloodedness– you are constantly exposed to the bacteria.
However, several strains of E. coli are capable of causing mild to serious and sometimes fatal, disease. These are known as enterotoxigenic (ETEC), enteropathogenic (EPEC), or enterohemorrhagic (EHEC) strains. EHEC strains of E. coli cause gastroenteritis with profuse watery diarrhea accompanied by nausea, abdominal cramps and vomiting. This bacterium is a common cause of travelers’ diarrhea. EPEC strains are similar to ETEC isolates but contain toxins that are capable of initiating severe disease. EHEC E. coli almost always belong to the single serological type 0157:H7. This strain generates a potent group of toxins that produce bloody diarrhea which can be fatal—especially for children and the elderly.
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WQRF Contaminant Occurrence Map
Check out the Contaminant Occurrence Map for visual representations of drinking water quality data for public water systems across the US. |
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Drinking Water Outbreaks
From 1982 to 2002, there were 350 documented outbreaks of E. coli O157:H7, a toxin-producing strain of the bacterium, representing 8,598 illness cases and 40 deaths. During this time, most (52%) of the E. coli outbreaks were due to contaminated food, however, at least 9% were from waterborne exposures. From 2002-2014 there have been an additional 9 documented E. coli outbreaks resulting in over 253 illness cases, 11 hospitalizations, and 1 death. Historically, most E. coli outbreaks associated with drinking water are due to inadequate treatment or contamination of the water supply after treatment and during distribution, highlighting the potential benefits of treatment at the point-of-use.
From 1982 to 2002, there were 350 documented outbreaks of E. coli O157:H7, a toxin-producing strain of the bacterium, representing 8,598 illness cases and 40 deaths. During this time, most (52%) of the E. coli outbreaks were due to contaminated food, however, at least 9% were from waterborne exposures. From 2002-2014 there have been an additional 9 documented E. coli outbreaks resulting in over 253 illness cases, 11 hospitalizations, and 1 death. Historically, most E. coli outbreaks associated with drinking water are due to inadequate treatment or contamination of the water supply after treatment and during distribution, highlighting the potential benefits of treatment at the point-of-use.
Treatment
Microfiltration, with a pore size of about 0.1 micron, is moderately effective for removing bacteria such as E. coli from drinking water supplies. However, ultrafiltration (~0.01 micron pore size) is highly effective in removing bacteria. Reverse osmosis systems are very highly effective at bacteria removal. Other technologies, such as distillation and UV light systems with pre-filtration, also have a very high effectiveness against bacteria.
Microfiltration, with a pore size of about 0.1 micron, is moderately effective for removing bacteria such as E. coli from drinking water supplies. However, ultrafiltration (~0.01 micron pore size) is highly effective in removing bacteria. Reverse osmosis systems are very highly effective at bacteria removal. Other technologies, such as distillation and UV light systems with pre-filtration, also have a very high effectiveness against bacteria.
Related Articles
Other Resources:
- 11/2006: E. coli in Spinach—Is There a Waterborne Link? [Link]
- 12/2008: What Does E. coli in Water Really Mean? [Link]
- 02/2011: Water Quality and Acceptable Risk: Are We Safe Enough? [Link]
- 07/2011: Germany’s E. coli Outbreak and Water Quality Protection Needs [Link]
- 08/2012: Water Quality Monitoring: How to Miss an Outbreak [Link]
Other Resources:
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