How health officials solved a deadly year-long listeria outbreak | The Big Story

Summary

The podcast episode explores an unusual listeria outbreak in Canada linked to plant-based milk brands like Great Value and Silk. Spanning nearly a year and affecting multiple provinces, the outbreak resulted in 20 cases and three deaths. The investigation faced challenges due to the long incubation period and delayed symptom onset. Epidemiologists traced the source back to a single production facility, leading to a product recall. The episode highlights the complexities of tracking foodborne illnesses and the vulnerabilities of certain populations to severe cases of listeria.

Takeaways

• 🔍 The outbreak of listeriosis in Canada spanned nearly a year and was linked to plant-based milks from multiple brands.
• 🚨 Three deaths have been reported in connection to this outbreak, which was traced back to products from Great Value and Silk.
• 🦠 Listeria is an environmental bacteria often found on food, especially protein-based products like deli meats and unpasteurized cheeses.
• 🤒 The symptoms of listeria can mimic a stomach bug, including fever, nausea, vomiting, and muscle aches.
• 🧪 The outbreak was difficult to track due to the 70-day incubation period of listeria, making it hard for people to recall what they ate.
• 🇨🇦 The outbreak affected 20 people across four provinces: Ontario, Alberta, Quebec, and Nova Scotia. Most of the severe cases occurred in Ontario.
• 🧬 The discovery of the outbreak was aided by genome sequencing of bacteria found in patients, revealing a common source.
• 🍶 Investigators traced the outbreak back to a specific third-party facility producing plant-based milk for the Silk and Great Value brands.
• 📅 Despite a recall in June, public health officials will not declare the outbreak over until early October due to the long incubation period.
• 👶 Vulnerable populations, such as people over 50, pregnant individuals, and young children, are at a higher risk of severe illness from listeria.

Q & A

What is the main focus of the podcast episode?

The podcast episode focuses on an unusual listeria outbreak in Canada, linked to plant-based milk products from the brands Great Value and Silk, and how epidemiologists traced its source.

What is listeria, and what are its symptoms?

Listeria is a type of bacteria that can grow on food, especially protein-based products. Symptoms include fever, nausea, vomiting, muscle aches, and, in severe cases, hospitalization or death. Many people may mistake it for a mild stomach bug.

How did the listeria outbreak in Canada spread, and how long did it last?

The outbreak spanned nearly a year across four provinces (Ontario, Quebec, Alberta, and Nova Scotia), with 20 reported cases. It was spread through plant-based milk products from different brands, but all traced back to a single production facility.

Why was it difficult to detect and track the outbreak initially?

The outbreak was difficult to detect due to the long incubation period of listeria (up to 70 days), making it hard for infected individuals to remember what they ate. Additionally, cases were spread out over months and across different provinces, delaying the connection between them.

What role did luck play in identifying the source of the outbreak?

Investigators got lucky when several infected individuals still had the contaminated plant-based milk in their fridges. This allowed them to check product codes, trace them back to the same production line, and confirm the source of the outbreak.

How severe was the listeria outbreak in terms of its impact?

Of the 20 reported cases, 15 people were hospitalized, and 3 people died, all in Ontario. The proportion of deaths relative to the number of infections was considered high.

Why were only certain individuals severely affected by the outbreak?

People most at risk were those over 50, pregnant women, young children, and others with weakened immune systems. Healthy individuals may have only experienced mild symptoms, similar to a stomach bug.

What measures were taken to control the outbreak?

Health officials issued a national recall of the affected products, and the Canadian Food Inspection Agency instructed companies to throw out plant-based milk with specific product codes. However, they remain cautious, as products with long expiry dates may still be in people's homes.

What can people do if they consumed plant-based milk during the outbreak?

If someone consumed the affected products but has not experienced severe symptoms, there is no need for panic or medical testing. Only those with serious symptoms or in vulnerable populations need to seek medical attention.

Is there a reason to be concerned about plant-based milk in general?

No, this was an isolated incident tied to a specific production line. There is no reason to believe that plant-based milk as a whole is unsafe. Consumers can continue using plant-based milk, just as they continued eating deli meats after the Maple Leaf Foods listeria outbreak.