Health officials in Alberta are investigating an uptick in cyclosporiasis, a parasitic illness that can cause severe diarrhea and is responsible for a large outbreak in the United States.
But the province said no connection has been made between the Alberta illnesses and the American outbreak, which has led to thousands of confirmed and suspected cases.
According to the health officials, six people have developed symptoms and tested positive since the beginning of May.
There have been no hospitalizations and no deaths.
Five became ill within the symptom-onset window reported by the U.S. Centers for Disease Control and Prevention (May 1 to July 9), according to the province. The sixth was confirmed July 15.
“Four of the five cases were associated with recent travel to Mexico, while none involved travel to the United States,” wrote Jaye Lang, the press secretary for Primary and Preventative Health Services Minister Justin Wright, in an email.
Health officials are looking into travel histories, food exposures and other potential links to outbreaks.
“While Alberta cases are being assessed against the cyclospora outbreak under investigation in the United States, no connections have been identified to date, and investigators have not identified a common food source or food establishment associated with the Alberta cases,” Lang said.
Dr. Lynora Saxinger, an infectious diseases specialist at the University of Alberta, isn’t surprised Alberta is seeing more cases, pointing to a recent surge in Quebec.
“There was actually a bigger spike of cases in Quebec and it was mostly people with travel-histories … mostly to Mexico,” Saxinger said.
Health officials in Quebec have said none of its cases appear to be linked to the U.S. outbreaks.
“They’ve had kind of a crazy weather year [in Mexico] with a lot of storms … that kind of circumstance can let essentially human sanitation get washed into agricultural water, which is where we think this is coming from,” Saxinger said.
“So, this could be part of a large-scale, increased number of cases in a lot of places.”
Cyclosporiasis symptoms include watery diarrhea, stomach cramps and mild fever.
“Sometimes people get quite debilitated with it, you know, and it can take a long time to get better — sometimes weeks to months,” Saxinger said, adding it can be treated with antibiotics.
Those at highest risk are the very young, the very old and those with compromised immune systems, she said.
Imported produce
Previous outbreaks in Canada have been traced back to imported produce. Investigators in the U.S. are eyeing lettuce or salad greens as the possible culprit there.
Cyclosporiasis does appear in Alberta from time to time.
The latest provincial disease surveillance report shows total case counts ranged from zero to 11 cases a year between 2020 and 2024.
Michael Gänzle, Canada Research Chair in food microbiology and probiotics at the University of Alberta, said outbreaks can occur when produce is brought in from countries with lower wastewater treatment standards.
The parasite can end up on fruits and vegetables when water, contaminated with human waste, is used for irrigation.
Leafy greens, raspberries, and herbs such as cilantro are often involved in outbreaks, according to Gänzle.
And it can be difficult to protect against cyclospora.
“Washing … doesn’t safely remove the parasite. It can reduce the count but it really doesn’t eliminate the risk,” he said.
“It appears to adhere quite strongly to the plant surface. And that means a little bit of gentle rubbing is not going to do the job.”
Being selective about the produce that you consume is the best protection against foodborne organisms like cyclospora, according to Gänzle.
“If you buy plants and eat them raw you have to trust your supplier,” he said.
Cooking produce can kill the parasite, according to Gänzle.
And he suggested buying locally-grown produce could help reduce the risk of contamination because water sanitation levels are high in Canada.
Meanwhile, the Public Health Agency of Canada said it is not currently investigating any cyclospora outbreaks in Canada.
If an outbreak is identified, provinces are expected to report to the federal agency and it will investigate when an outbreak spans more than one province or territory.
For its part, the Canadian Food Inspection Agency (CFIA) said it conducts year-round surveillance and testing for cyclospora.
And it has not identified cases of the parasite related to the U.S. outbreak.
“Canada is one of the few countries in the world that routinely tests fresh produce for cyclospora,” an agency spokesperson wrote in an email.
“Routine testing focuses on imported fresh produce that has historically been associated with cyclospora contamination, including raspberries, blackberries, whole and cut leafy vegetables (such as lettuce and salad mixes), and fresh leafy herbs, including cilantro and basil.”
The CFIA said no additional testing measures are being introduced in response to the U.S. outbreak.
