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Twelve people were sick enough to visit local hospitals after eating the same chicken dish from a Markham, Ont., restaurant over the weekend. 

Dr. Barry Pakes, York Region's medical officer of health, says a spice contaminated with the plant-based toxin aconite is believed to be responsible for the illnesses. Here are five facts about it:

What is aconite?

Aconite is a highly toxic alkaloid substance derived from a particular genus of plants, Aconitum. It is sometimes called wolfsbane or monkshood and is found in herbs, roots or a flower.

Where is it found?

Aconite can be found across the Northern Hemisphere. It can also be found in some traditional Chinese medicines once processing methods have been used to eliminate the toxin.

What happens if it's consumed?

The toxin affects nerves that control muscles in the body and can lead to symptoms such as numbness in the face and extremities and severe gastrointestinal distress. It can disrupt the electrical network of cells and signals that control the heart, leading to an irregular or ineffective heartbeat, followed by blood loss to organs, including the brain.

If consumed in large enough quantities, aconite can cause fatal arrhythmia.

Nausea, vomiting, cramping and muscle weakness can also be symptoms of aconite poisoning.

Pates, York Region's top doctor, says the toxin acts quickly and can make those who ingest it ill enough to head to the hospital within an hour of consuming it.

Dr. David Juurlink, head of clinical pharmacology and toxicology at the University of Toronto, tweeted that effects occur quickly after consuming the toxin and are primarily neurological, cardiac or gastrointestinal.

What is the treatment?

Juurlink said there is no specific antidote for curing aconite poisoning, and that most treatments are supportive – meaning they focus on preventing, controlling or relieving complications and side effects.

How does aconite get mixed into food?

Pakes says aconite can occasionally be accidentally included in certain spices or herbal remedies.

Local public health officials are working with provincial and federal partners to determine whether the spice product believed to be at the centre of the Markham case was available in retailers other than the Markham-area one it's been located and removed from. But Pakes said, the risk was "very, very low" and the product is "very uncommonly used." 

In March, B.C.'s poison information centre and the Fraser Health Authority warned the public not to consume Wing Hing brand sand ginger powder after two people were hospitalized. They later recovered.

Pakes did not name the spice suspected in the Markham case, but confirmed it is not sand ginger powder.

This report by The Canadian Press was first published Aug. 30, 2022.

The Canadian Press