Researchers have expanded knowledge of the UK’s involvement in a multi-country Listeria outbreak. Twelve patients were detected in the UK between 2015 and 2018; contaminated sweetcorn was recovered from the freezer of another person subject in 2019.
Overall, the outbreak included 54 cases of listeriosis in Australia, Finland, Sweden, Denmark, Austria, and the UK with 10 deaths. It was traced to a frozen vegetable factory in Hungary that in 2018 was owned by Greenyard.
In the UK, the outbreak strain was detected in a chicken and sweet corn sandwich filling from a manufacturer in June 2018. The producer added frozen sweet corn directly to fillings without additional cooking or blanching. Sampling was done during routine testing and was not part of the outbreak investigation. The company has now put in place additional controls, which include a heating step for frozen sweet corn before adding it to the sandwich filling.
The sweet corn was supplied by Greenyard Frozen UK, a distributor in England, that got frozen products from Greenyard in Hungary. The study, published in the International Journal of Food Microbiology, showed that sweet corn was more frequently contaminated than other frozen vegetables collected at Greenyard Frozen UK.
A total of 208 food and environmental samples were taken at the distributor’s two sites. Listeria monocytogenes was detected in 31 of 70 samples of frozen sweet corn and 5 percent of 79 other foods.
