An outbreak of extensively drug-resistant salmonella has been linked to raw pet food and contact with cattle, according to the Public Health Agency of Canada (PHAC).
In a Nov. 11 public health notice, the agency said 40 cases have been confirmed in six provinces, including 21 cases in Quebec, 14 in Ontario, two in Nova Scotia, and one each in Manitoba, New Brunswick and Prince Edward Island. Thirteen people have been hospitalized.
“Many of the individuals who became sick are children five years of age or younger,” the notice said. “The Salmonella strain associated with this outbreak investigation is extensively drug-resistant, which means it’s resistant to all commonly recommended antibiotics.”
Although cases date from July 2020 to September 2023, the outbreak is considered ongoing as illnesses continue to be reported. While there have been no human deaths, some infected dogs and cattle have died. Children under five represent 43 per cent of all cases.
“Some of the individuals who became sick reported exposure to raw pet food, or to dogs fed raw pet food, before their illnesses occurred,” the public health notice explained. “Contact with cattle, particularly calves, has also been identified as a likely source for some of the illnesses reported in the outbreak.”
A common pet food supplier has not been identified in the ongoing investigation, which is being conducted by the Public Health Agency of Canada along with provincial public health departments, the Canadian Food Inspection Agency and Health Canada. Other sources of infection could still be uncovered.
“Probably, it’s being spread to people through contact with the contaminated products… so people handling raw pet food that’s contaminated unbeknownst to them, and then contaminating themselves or people around them with the product,” McMaster University biochemistry and biomedical sciences professor Brian Coombes told CTV News Channel. “It could be spread from person to person as well. So, if someone has contaminated themselves inadvertently, they can (spread) germs to other people in the same household.”
In humans, symptoms of salmonella infection typically start six to 72 hours after exposure and can include four to seven days of fever, vomiting, diarrhea and abdominal cramps. Infected people and animals can continue to spread salmonella for weeks after symptoms disappear through individual contact and contaminated surfaces.
While most people recover fully without treatment, salmonella infection can lead to severe illness and hospitalization, particularly among older adults, young children, pregnant people and those with weakened immune systems.
“Of course drug resistance is the big problem, and for especially children under five who become critically sick and need to be hospitalized,” Coombes said. “Unfortunately there would be very few pills on the shelf that could be used to try and treat someone who’s critically ill. They would probably be in hospital on supportive therapy, so IV fluids probably, and hoping that our body’s natural immune defences, like our innate immune system, can do its job effectively to try and help those patients eradicate the infection.”
Due to the risk of bacteria like salmonella and E.coli, PHAC does not recommend feeding your pets raw food, especially in households with young children and the immune-compromised. Animals can pass on harmful bacteria like salmonella through their feces even if they appear healthy.
Those who decide to use raw pet food are encouraged to wash their hands thoroughly after preparing food and handling their pets. Raw pet food should be stored and prepared away from human food and kept in a sealed container if refrigeration or freezing is necessary. Dedicated containers and utensils should also be used and sanitized along with affected surfaces.
PHAC says dogs that eat raw pet food shouldn’t be allowed to lick people’s faces, mouths or wounds. Hands should also be washed thoroughly when touching cattle or visiting a farm or petting zoo.
Jennifer Ronholm, an associate professor of animal science, food science and agricultural chemistry at McGill University, says extensively drug-resistant salmonella was first detected in Canada in cattle in 2019.
“In terms of antibiotic-resistance in salmonella, it’s unfortunately getting more common every year,” Ronholm told CTV News. “In 2010, about 10 per cent of the salmonella we were seeing in Canada was multi-drug resistant, and by 2019 we’re seeing over 60 per cent being multi-drug resistant.”
Ronholm believes the outbreak is likely affecting many more animals than health officials currently know about.
“This is a little bit rare that something goes on this long, but it’s not unheard of,” Ronholm explained. “What it indicates is we haven’t found the source yet, so you probably have a source at a processing facility, or a source at a distributor, or a source on a farm somewhere where people are sourcing their ingredients that has an ongoing outbreak but doesn’t know it yet. So until we can find the exact source of the contamination, there’s not much we can do about it.”
#Outbreak of #Salmonella linked to exposure to raw pet food or to cattle. Sanitize areas that come into contact with raw pet food. Wash your hands after handling raw pet food, interacting with cattle or raw-fed dogs. Learn more : https://t.co/7lkX4ddaQb pic.twitter.com/Acj3hzrNr2
— Health Canada and PHAC (@GovCanHealth) November 13, 2023