Some people who grow and sell organic food in New Brunswick are disputing suggestions their customers are more vulnerable to E. coli infection.

Earlier this week, following an outbreak of a potentially deadly strain of the infectious bacteria in Fredericton, a leading scientist told CBC News organic vegetables are more susceptible to E. coli contamination because producers use animal manure fertilizer instead of chemicals.

There are four confirmed cases of E. coli O157:H7 in Fredericton, public health officials have said.

That’s the same strain that killed seven people during the tainted water scandal in Walkerton, Ont., in 2000.

At least two of the latest victims have been hospitalized while public health officials continue to investigate, trying to determine the source.

'This gentleman ought to make himself more knowledgeable of the Canadian Organic Productions standards. And that's through the Canadian Food Inspection Agency. And that's by law.'—Karen Davidge, organic farmer

Dr. Denis Allard, the province's acting chief medical officer of health, has said it could be another week before he has any new information for the public and that the source may never be identified.

But Karen Davidge, a certified organic farmer in Keswick Ridge for 32 years, disputes the idea that organic produce is any more likely to have E. coli than produce from traditional farms.

“This gentleman ought to make himself more knowledgeable of the Canadian Organic Production Standards. And that's through the Canadian Food Inspection Agency. And that's by law,” said Davidge, who runs Good Spring Farm.

She says there are numerous health and safety guidelines organic farmers must follow.

For example, those who make and use their own organic compost must use heat to kill any E. coli, said Davidge, who buys certified organic compost from another farm, complete with paperwork.

“And on this farm, we don't do the hot composting. So therefore, we are only allowed to use the compost from our manure for crops that are not an edible crop in the same year,” she said.

Still, she says it’s a good idea for people to wash whatever vegetables they eat – organic or not.

Proper washing important

Andy Camm, executive sous chef at the Delta Fredericton, says he handles organic produce the same as non-organic. (CBC)

Andy Camm, the executive sous chef at the Delta Hotel in Fredericton, says they serve about 10 per cent organic food and don't handle it any differently than non-organic.

"We treat it the same as we would our regular produce that comes in. If it's organic, we still wash it the same, we still handle it the same," he said.

Handwashing is also important, Camm said.

"Definitely wash your hands after everything — you touch meat, you wash your hands. You touch carrots, you wash your hands," he said.

People should also use a different cutting board for meat and produce and ensure meat is cooked to the proper temperature, said Camm.

He learned first-hand the importance of proper food handling when he got sick after eating some fast food during a trip.

"Shaking sweating, vomiting, everything coming out of your body every which way and it lasts for about 12 hours. Ya, it was bad."

Organic more susceptible

Epidemiologist Tim Sly says leafy greens, such as lettuce, are often the source of E. coli. (CBC)

Tim Sly, an epidemiologist and professor of risk assessment at Ryerson University’s school of occupational and public health, told CBC News organic vegetables are more susceptible to E. coli.

"Organic food, by definition, means you haven't used a chemical fertilizer, you've used compost or manure. And should that not be fully rotted down, sort of self-heat treated, if you like, who is to say it is, we can see an increase in this kind of risk," he said.

"Vegetables you don't cook before you eat them, growing close to the ground, where the ground has been fertilized with manure, this is a risk.

'If you are going to eat organic food, you should make sure that it's properly cooked or really washed to within an inch of its life.'—Tim Sly, epidemiologist

"And you combine that with another movement, which is the raw food movement, and it seems to be these movements, side by side, and you get a double whammy."

Leafy greens, such as lettuce and spinach are often the source of E. coli, said Sly.

“If you are going to eat organic food, you should make sure that it's properly cooked or really washed to within an inch of its life because organic food will be more contaminated by definition than food that’s not organic food,” he said.

Pre-shredded and mixed lettuce is often more prone, Sly said.

“We've found that the E. coli tends to cling to the cut and torn edges of a lettuce leaf and it doesn't tend to cling too well to the smooth entire lettuce leaf.

“So buy a lettuce leaf that's entire, trim off the torn bits and wash that really thoroughly under running water. That's the best way to do it.”

Sly also recommends avoiding undercooked meat and not drinking unpasteurized milk.

E. coli O157: H7 secretes a powerful toxin that can destroy red blood cells leading to severe illness, high blood pressure and kidney damage.

Those most at risk of developing serious complications include pregnant women, young children, seniors and people with a weakened immune system, such as those on chemotherapy.