Researchers aim to prevent tainted food at source
A Canadian researcher says preventing food contamination, like the E. coli-tainted spinach distributed across North America last year, may involve stopping the bacteria at its source.
The most recent E. coli contamination killed three people in the U.S. and left more than 190 others sick. Investigators traced the source to California, where they suspect the bacteria came
from cattle feces.
“I believe the same strain of E. coli was found in the feces in a farm close to the fields where they were growing the spinach,” Prof. Mansel Griffiths, director of the Canadian Research
Institute for Food Safety, told CTV.ca.
He said researchers at Ontario’s University of Guelph, where his institute is based, are looking at ways to prevent cattle from shedding E. coli in the first place.
“Now there are things like vaccines being trialed,” he said. “And some work that’s being done in Guelph on the use of bacteriophage — those are viruses that are specific to bacteria —
to treat the animals, to kill the organism before it sheds in the feces.
This, he says, is just one of a number of intervention strategies that are being looked at, to try and reduce environmental contamination.
How E. coli moves through the system
Most strains of E. coli are harmless to humans, with the major exception being E. coli O157:H7. It forms in the intestines of cattle, who remain healthy but shed the bacteria in their feces.
Humans infected with E. coli also transmit the bacteria to their stools, and can infect others if they do not properly wash their hands or practice safe hygiene.
E. coli, or Escherichia coli, causes symptoms in humans within two to eight days of infection. Typical signs are painful stomach aches, vomiting, bloody feces and even fever. In rare cases, the
bacteria can cause Hemolytic Uremic Syndrome — a type of kidney failure that can be fatal.
While researchers point to the possible success of using vaccines and bacteriophage, there’s still the question of wild animals. Not only do cattle carry E. coli, but also chickens, wild deer,
pigs and sheep.
“It’s a huge problem now that there are issues around wild animal populations, along with some of these farms that are close to animal production facilities,” said Griffiths.
“There are a number of problems that are not easy to overcome.”
But what officials can still do is promote good agricultural practices, like making sure irrigation water and fertilizers are free from contamination.
It also means making sure those who handle produce “follow good hygienic practices, so provide them with adequate toilet facilities,” said Griffiths. “And that includes hand-washing
A number of Canadian agricultural organizations have developed farm food safety guidelines, which they ask producers to follow carefully.
While the Canadian Food Inspection Agency has the authority to recall products, their U.S. counterpart, the Food and Drug Administration, can only offer guidelines for the industry.
Still, individual states are enforcing their own regulations. California, the source of the E. coli-tainted spinach, has come up with the Leafy Green Marketing Agreement. It’s a voluntary
agreement that businesses will only “buy or handle” leafy green products from growers who follow a set of safety regulations.
About 90 per cent of California processors will follow the mandatory rules, according to The New York Times.
But what of food imported from outside North America? The recent pet food recalls were prompted by melamine-tainted wheat gluten traced back to China.
While there are no reports any of the wheat gluten entered the human food chain, it’s not the first time companies have imported harmful food from outside North America or Europe.
“There have been a whole bunch of things in the past related to food safety,” Griffiths said. “The whole business of the Sudan I red dye that happened about two years ago — certainly
these things happen.”
Sudan I is banned in Canada because it’s been found to cause cancer in laboratory animals. In 2005, the substance found its way into Britain and led to the recall of more than 450 products.
It’s been suggested the dye came from a company in India, and may have been imported before the ban came into effect.
“No matter how many regulations you put in place, you can’t get to a stage where you have a zero risk,” said Griffiths.
“You can only mitigate the effects of some of these problems.”