Six people in Australia are part of an international Listeria outbreak traced to imported mushrooms that has also killed four in the United States.

The Listeria monocytogenes patients in Australia have been identified by whole genome sequencing as being related to the U.S. outbreak strain. Their illnesses were reported between October 2017 and March this year.

Food Standards Australia New Zealand (FSANZ) said the investigation was ongoing but no deaths have been attributed to listeriosis amongst cases.

Of the six infections in Australia related to the U.S. outbreak strain, four are thought to have been exposed in the country. Of these, three are residents of Queensland, and one is from New South Wales. The other two are thought to have been exposed while travelling overseas. The median age of cases is 75 years old, four are female and two are males, and all of them had underlying health conditions.

Listeria monocytogenes was detected in enoki mushrooms imported from South Korea that were recalled in the country earlier this month.

Choi’s Mushrooms recalled Green Co. Enoki Mushrooms in 200-gram and 300-gram packages. The products were sold at Asian supermarkets and grocers in New South Wales, the Australian Capital Territory, Victoria, Queensland and South Australia. Both products have date markings: April 22, May 5, May 12, May 19 and May 26, 2020.

Enoki mushrooms are a long thin white mushroom, usually sold in clusters. They are popular in East Asian cuisine and also known as enokitake, golden needle, futu or lily mushrooms.

Korean authorities and enoki mushroom suppliers are trying to ensure sanitary controls are being met and cooking instructions are put on packaging. In Korea, enoki mushrooms are cooked and not eaten raw in salads.

American and Canadian recalls
In the U.S., three enoki mushrooms recalls have been issued. They are H&C Food Inc., Guan’s Mushroom Co. and Sun Hong Foods, Inc. A total of 36 people infected with the outbreak strain of Listeria monocytogenes have been reported from 17 states and 30 needed hospital treatment. Listeria has been identified in ill people from November 2016 to mid-December 2019.

The Food and Drug Administration (FDA) sampled enoki mushrooms at import from Green Co. of the Republic of Korea. Results showed two samples yielded the outbreak strain. Green Co. was placed on import alert and H&C Foods Inc. recalled enoki mushrooms supplied by the company. This move flags imported shipments from this firm for potential detention without physical examinations.

In Canada, another make of enoki mushrooms was recalled in late March. Goldenway International Trade Co. Ltd. recalled Golden Mushroom brand Enoki Mushroom because of possible Listeria monocytogenes contamination.

The action was triggered by Canadian Food Inspection Agency (CFIA) test results but no reported illnesses have been associated with the product.

about Listeria infections
Food contaminated with Listeria monocytogenes may not look or smell spoiled but can still cause serious and sometimes life-threatening infections. Anyone who has eaten any of the recalled products and developed symptoms of Listeria infection should seek medical treatment and tell their doctors about the possible Listeria exposure.

Also, anyone who has eaten any of the recalled product should monitor themselves for symptoms during the coming weeks because it can take up to 70 days after exposure to Listeria for symptoms of listeriosis to develop. 

Symptoms of Listeria infection can include vomiting, nausea, persistent fever, muscle aches, severe headache and neck stiffness. Specific laboratory tests are required to diagnose Listeria infections, which can mimic other illnesses. 

Pregnant women, the elderly, young children, and people such as cancer patients who have weakened immune systems are particularly at risk of serious illnesses, life-threatening infections and other complications. Although infected pregnant women may experience only mild, flu-like symptoms, their infections can lead to premature delivery, infection of the newborn or even stillbirth.