The Food Standards Agency (FSA) and Food Standards Scotland (FSS) have advised vulnerable consumers to thoroughly cook enoki mushrooms due to the risk of Listeria contamination.

Analysis of FSA and local authority sampling data has found the presence of Listeria monocytogenes in 13 of 40 samples of enoki mushrooms tested, sometimes at high levels. Contaminated mushrooms have been imported from China, South Korea, Thailand, and other Asian countries.

Enoki mushrooms, sometimes labeled as Enokitake, Golden Needle or Lily Mushrooms, are tall, white, thin-stemmed mushrooms, which are common across Asia. While they are usually cooked, they can occasionally be served raw in salads.

Labeling is not always in English or clear in telling consumers to cook the product before consumption and not to eat it raw.

Link to past outbreaks
There has not yet been any cases of listeriosis tied to Enoki mushrooms in the UK, but they have been linked to outbreaks and illnesses in the United States, Canada, and Australia.

The U.S. Centers for Disease Control and Prevention reported an outbreak that sickened five people in four states from October 2022 to February 2023. All patients required hospitalization.

A 2016 to 2020 outbreak affected 48 people, 36 in the U.S. and 12 in Canada with four deaths. Health officials in Australia investigated six listeriosis cases with clinical isolates related to the outbreak strain and illness onset dates between 2017 and 2020.

France had five related enoki mushroom isolates to the outbreak strain but didn’t record any patients, according to a study published in the Journal of Food Protection.

Earlier this year, a consultation was held in England, Wales, and Scotland that included adding enoki mushrooms from China and South Korea to a list of products to be controlled, at a frequency of 20 percent for Listeria. This recommendation has to be put to ministers to decide but legislation could come into force in 2024.

Public health advice
The risk of serious illness from listeriosis increases with age, while pregnant women and those with a weakened immune system are also more vulnerable.

Stuart McAdam, head of incidents at Food Standards Scotland, said the advice is that the mushrooms can be contaminated with Listeria, so should be stored in the fridge at 5 degrees C (41 degrees F) or below and handled carefully.

“You should properly clean any surfaces and utensils you’ve used to prepare them and wash hands. Those who are pregnant or have weakened immune systems should cook Enoki mushrooms thoroughly before eating them as this will destroy any Listeria monocytogenes present, which can cause serious illness in vulnerable consumers,” he said. 

FSS, FSA, local authorities and port health authorities have informed food businesses and importers of the risks associated with enoki mushrooms and reminded them of food safety and labeling requirements.

(To sign up for a free subscription to Food Safety News, click here.)