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Reducing salmonella risk from contaminated produce studied at Wilfrid Laurier

Laurier part of larger project involving several universities, by Carmen Ponciano, July 27, 2017 

Wilfrid Laurier University in Waterloo, Ont. is looking into ways of controlling the presence of the food-poisoning bacteria salmonella on fresh produce as part of a larger project that involves several universities in North America, called Salmonella Syst-OMIC.

Salmonella is usually associated with under-cooked or uncooked chicken, but people can also get sick from fruits and vegetables that have been contaminated with the bacteria.

Overall, the project looks to improve methods of testing and controlling salmonella in produce, and develop tools for public health departments to determine the source of salmonella bacteria early on when an outbreak happens so that food is removed from grocery stores before someone buys it.

Laurier's role in the project focuses on trying to understand salmonella and all 2,500 variations of the bacterium, while researching its ability to produce.

"It can persist on the surface of the vegetables, [but] whether it's thriving and growing, that's one of the things that we are trying to understand," Joel Weadge, a professor in the faculty of biology at Wilfrid Laurier, told CBC's The Morning Edition host, Craig Norris.

Using this information, they want to be able to knock down common strains of salmonella by combining viruses that are not dangerous to humans, and create a spray. 

Trendy increase 
Salmonella comes in contact with produce from manure spread on fields.

Each year, about 88,000 people in Canada get sick from salmonella poisoning and researchers with Salmonella Syst-OMIC announced produce has recently emerged as a source of the bacteria.

Weadge said an increase in reported cases may be attributed to the healthy trend of eating fresh produce, like salads, and the short time it takes for produce to get to people's kitchen from the time it's harvested.

"People are trying to eat healthy and want to eat things that are more fresh," he said. "If you cook your vegetables there is not much of an issue but with this health trend [of eating fresh and raw produce], it introduced this organism into our lives."

He said researchers have seen outbreaks in sprouts and melons, but are seeing an increase of salmonella outbreaks from leafy greens like lettuce and even tomatoes.

He advises there is no obvious way to know if produce is contaminated with salmonella. The best way to protect yourself is by washing your produce and cooking your vegetables.

Effects in food industry
Salmonella doesn't just make people sick. Its effects can also be felt in the food industry due to the cost of food recalls and potential damage to the supplier's brand.

Weadge said the current policy states a single failed salmonella test can close a facility and prompt a recall. But he believes this zero tolerance approach needs revision because some salmonella are more pathogenic than others.

"There are over 2,500 different types of salmonella, some are very dangerous and some are rather benign," he said.

He adds that if they are able to determine how pathogenic certain salmonella are through the Salmonella Syst-OMIC project, officials wouldn't have to throw away produce that is not as dangerous to humans and focus recall efforts on the ones that are more severe and may lead to outbreaks.