An analysis coordinated by the National Reference Center for Listeria, Santé publique France and the French General Directorate for Food, in collaboration with Belgian, German and Dutch experts, has concluded that a listeriosis outbreak that occurred in Europe was linked with the consumption of vegan, plant-based cheeses. It found that the proliferation rate of Listeria monocytogenes is actually higher in vegan milk than in raw animal milk.
Between April and December 2022 in France, four pregnant women and one immunocompromised individual were infected with Listeria monocytogenes bacteria, which cause listeriosis, a severe foodborne infection. A Europe-wide alert led to the identification of three additional cases of listeriosis, in Belgium (a three-year old child), Germany (a pregnant woman) and the Netherlands (a newborn baby born to an infected mother). The infections were all caused by the consumption of contaminated plant-based cheeses.
It was epidemiologically proven that the infected individuals had been exposed to these products, leading to product recalls and an urgent call from the French national public health authority to inform consumers, especially pregnant women, of the risk of listeriosis linked to the consumption of vegan cheese products.
What is vegan or plant-based cheese?
Vegan cheese is made from almond, cashew or coconut milk. These plant-based substitutes imitate dairy cheeses and are thought to be exempt from pathogens of animal origin such as Listeria monocytogenes.
Plant-based cheese alternatives are therefore marketed as safe options for those wishing to avoid raw milk cheese.
- Raw milk cheese contaminated with Listeria monocytogenes places consumers at high risk of listeriosis and so is not recommended for pregnant women and people with weakened immune systems.
- Since vegan cheeses do not generally undergo pasteurization – a food safety process that extends shelf life by destroying microorganisms –, they can be contaminated by a poorly managed production environment.
Vegan cheese contaminated by Listeria monocytogenes bacteria
A study was conducted by Munster Technological University in Ireland to compare the proliferation of these bacteria in plant-based milk and bovine milk. The scientists demonstrated that Listeria monocytogenes proliferated at higher rates in plant-based milks. Physicochemical properties such as pH are thought to be behind the growth of Listeria monocytogenes bacteria in these types of milk.
This outbreak detected in Europe, together with cases of contamination with Salmonella in vegan cheese in the United States, highlight the lack of data on vegan products contaminated with foodborne pathogens.
The study also points to a need for vegan cheese producers to take these risks into account during the production process.
This study is part of the priority scientific area Antimicrobial Resistance of the Institut Pasteur's strategic plan for 2019-2023.
Source
Outbreak of Listeriosis Associated with Consumption of Vegan Cheese, New England Journal of Medicine, 17 avril 2024
- Alexandre Leclercq, M.Sc., Institut Pasteur, Paris, France
- Mathieu Tourdjman, M.D., Santé Publique France, Saint-Maurice, France
- Wesley Mattheus, Ph.D., Sciensano, Brussels, Belgium
- Ingrid Friesema, M.D., Rijksinstituut voor Volksgezondheid en Milieu Utrecht, the Netherlands
- Nina M. van Sorge, Ph.D., Amsterdam UMC, Amsterdam, the Netherlands
- Sven Halbedel, Ph.D. & Hendrik Wilking, D.V.M., Ph.D., Robert Koch Institute, Berlin, Germany
- Marc Lecuit, M.D., Ph.D., Institut Pasteur, Paris, France