An Overview of Listeriosis Outbreak Investigations in the United States Linked to Imported Enoki Mushrooms and Associated Regulatory Activities, Research, and Food Safety Knowledge Gaps

Abstract

Foods implicated in listeriosis outbreaks continue to change over time. Historically, listeriosis outbreaks have been primarily linked to consumption of deli meat and dairy products. More recently, they have been linked to vegetable row crops, fruits, and other produce, including imported specialty mushrooms. Specialty mushrooms, including enoki mushrooms, are popular in Japanese, Chinese, and Korean cuisines, and are commonly used in soups, stir-fries, hotpots, and salads. These mushrooms are imported into the U.S. from a variety of East Asian countries and Canada. Recently, food safety authorities around the world have linked listeriosis outbreaks to contaminated enoki mushrooms, leading to a series of highly impactful recalls. This review examines outbreaks and recalls associated with enoki mushrooms, related risks and food safety concerns, ongoing research, regulatory activities focused on this commodity, consumer preparation and handling practices, and prevention strategies. The exchange of epidemiologic and traceback evidence, genomic data, and international data sharing helped investigators find the source of multiple listeriosis outbreaks linked to enoki mushrooms. Since enoki mushrooms were first linked to listeriosis illnesses in 2020, state, federal, and international partners developed a strategy for outbreak prevention, including enhanced surveillance and an improved investigational approach for this commodity.

Keywords: Listeria monocytogenes; enoki mushrooms; outbreaks.