Health officials are racing to trace supplies of a spice product suspected of poisoning a dozen diners at a Toronto-area restaurant amid concerns it could be on shelves elsewhere in Canada.
At least 12 people fell seriously ill, with four requiring treatment in intensive care, after eating at Delight Restaurant & BBQ in Markham, Ont., on the weekend. Five remained in hospital on Tuesday, and York Region Public Health said they were all expected to fully recover.
Officials believe all 12 consumed the toxin of an aconitum plant, which is popular in traditional Chinese medicine, in a chicken dish at the restaurant.
Aconite toxin affects nerves that control muscles in the body, leading to numbness in the face and extremities, severe gastrointestinal distress and, in some cases, an irregular heartbeat. Ingested in large enough quantities, aconite can induce fatal arrhythmia of the heart.
Dr. Barry Pakes, York Region's medical officer of health, on Tuesday told CBC News that officials believed the restaurant had used an "accidentally contaminated" spice product, and provincial and federal agencies were trying to trace whether it had been distributed elsewhere in Canada.
"It seems like this is a fairly small batch kind of situation, or a distributor or a product that is fairly niche," he said.
"The main focus of our work is to figure out where it might have gone, and to make sure that we get all of that product off the shelf."
Pakes said York Region Public Health was awaiting test results from a federal lab to confirm the cause of the poisoning. The Canadian Food Inspection Agency said only that it was "providing support as the source is being investigated."
"If an affected food product is identified, the CFIA will work with industry to recall the product as soon as possible," the agency said in a statement.
Delight Restaurant & BBQ was closed on Monday and Tuesday, and did not respond to requests for comment.
The restaurant was cleared to re-open on Wednesday, said Pakes.
"We don't see there as being any safety risk at that restaurant. We've gone back and re-inspected it, and they'll be opening," he said. "In the case of a small business like this, there's no reason to keep them closed. We're very confident of what the offending item actually was."
'The queen of poisons'
There are about 240 species of aconitum, also known as monkshood and wolfsbane, across Asia, North America and Europe. Though popular with gardeners because of their bright flowers, which are usually purple or blue, most of the species are extremely poisonous and must be handled with care.
"There's monkshood that are in gardens all over the world because they're beautiful plants. They're late-blooming. Bumblebees love them," said Roger Gettig, director of horticulture at the Toronto Botanical Garden.
He recommended wearing rubber or leather gloves while handling the plant to avoid coming into contact with the toxin.
The plant's poison has been used for centuries in hunting and battle, applied to arrows and spears used to kill animals and enemies, as well as being name-checked in pop culture — from John Keats' poem Ode to Melancholy to Harry Potter's wolfsbane potion.
It's not only fictional killers who are drawn to the poisonous plant: in 2010, a British woman was convicted of killing her former lover by putting aconite in his leftover curry.
"The lethal dose in humans can be as little as two milligrams, which is very small amounts — kind of the size of a sesame seed," said Dr. Prateek Lala, assistant professor and associate director of applied clinical pharmacology at the University of Toronto.
"The dose that each [Toronto] patient got must have been much, much lower than that if they're already on the path to recovery. And that's obviously a good thing."
Aconite poisonings 'unusual' in Canada
In 2004, 25-year-old actor Andre Noble died after apparently ingesting monkshood sap in his home province of Newfoundland.
And in early February of this year, two people in British Columbia needed hospital treatment after eating ginger powder that contained aconitum.
But such cases are rare, says Dr. Margaret Thompson, medical director of the Ontario Poison Centre. She estimated the centre logs one case every five years.
Past cases have involved people ingesting too high a concentration of a product intended for medicinal use, while others had mistaken the plant for another herb, such as parsley, she said.
"That actually happens when it's not flowering, because they [think] it is just a nice green plant. People would actually think, 'Oh, I can put some of this in a salad,'" Thompson said. "It's just an accidental misidentification."
There is no antidote for aconite poisoning, so treatment focuses on supportive care, including activated charcoal if the patient seeks treatment early enough, and anti-nausea medications and fluids if they are suffering vomiting or diarrhea. Patients may require a ventilator to help with breathing, or even defibrillation to restore a normal heartbeat, Thompson said.
Aconitum as a remedy, not a recipe
Aconitum roots are regularly used in Eastern herbal remedies, including in traditional Chinese medicine and Ayurvedic medicine for rheumatoid conditions or as a topical or internal anesthetic — but only after an intricate process to remove the plant's toxins.
Tim Sibbald, a teacher at the Ontario College of Traditional Chinese Medicine, says TCM protocol requires that aconitum roots be boiled for one to two hours to reduce their toxicity. A TCM practitioner will then take chopsticks, dip them into the concoction, then dot the liquid on their tongue to check the toxicity.
"If there is a sensation of numbness and tingling, then you have not yet gotten rid of the toxicity of that herb, and so it cannot yet be used," Sibbald said.
"The issue is less one of dosage, because with almost any dose, there is the potential for fatality," he said. "It is whether or not it has been processed properly."
WATCH | Health officials suspect aconite poisoning sickened restaurant patrons:
Both Sibbald and Chris Pickrell, a Toronto naturopath, herbalist and TCM practitioner, said it would be unusual for aconitum to be used in a Chinese food recipe.
"There are no traditional recipes I know of where that would show up … It has lots of great uses in Chinese medicine, but it's never used in cooking," Pickrell said.
While sliced aconitum root and dried ginger can look similar, their Chinese names are quite different, so it was unlikely their labels would be mistaken for each other, he said.
York Region Public Health said anyone who had weekend leftovers from the restaurant should throw them out. If anyone who ate from the restaurant had symptoms, they should seek medical attention.