FAO and WHO experts are to look again at Listeria monocytogenes in ready-to-eat (RTE) foods.

The move by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) is due to developments in diagnostics and changes in the epidemiology of listeriosis outbreaks.

The Joint FAO/WHO Expert Meetings on Microbiological Risk Assessment (JEMRA) is planned for Oct. 20 to Nov. 6.

Update knowledge
A 2004 FAO and WHO risk assessment on Listeria monocytogenes provided scientific insight into the risk characterization of Listeria contamination in food and the seriousness of listeriosis for susceptible populations.

The technical report was limited to certain RTE foods including pasteurized milk, ice cream, cold-smoked fish and fermented meats, and the likelihood of these products as vehicles for foodborne listeriosis.

Since then, outbreaks continue to occur across the globe, associated with known and many previously unreported food vehicles, including fresh and minimally processed fruits and vegetables, sprouts, RTE meat products, and frozen dairy products.

New tools are now available to characterize isolates of Listeria monocytogenes. New research and data representing the different food commodities and geographical regions will provide opportunities to validate the current risk assessment models for Listeria monocytogenes, assess their application to other foods, and develop management approaches to control this pathogen.

Outbreak examples
The largest and deadliest outbreak of listeriosis to date was recorded in 2017 and 2018 in South Africa. It was linked to RTE meat products and caused more than 1,050 illnesses and at least 218 deaths.

It was traced in March 2018 to a RTE processed meat product called polony made at a factory in Polokwane run by Enterprise Foods, then-owned by Tiger Brands. In August this year, Tiger Brands agreed to sell its processed meats division, which includes Enterprise Foods.

Spain recorded its largest listeriosis outbreak in 2019. It was linked to “La Mecha” brand chilled roasted pork produced by Magrudis. More than 200 people were affected including three deaths in elderly people and six pregnant women lost their babies. The listeriosis alert started in mid-August and ended by mid-October 2019.

An international outbreak from 2015 to 2018 was traced to frozen sweetcorn and vegetables produced by Greenyard in Hungary. It included 54 cases in Australia, Finland, Sweden, Denmark, Austria, and the UK with 10 deaths. The implicated frozen products were distributed to 116 countries.

The 2018 zoonoses report by the European Food Safety Authority (EFSA) and European Centre for Disease Prevention and Control (ECDC) found there has been a statistically significant increasing trend of confirmed listeriosis cases in Europe from 2009 to 2018. Around 2,550 infections were recorded in 2018.

A list of experts proposed for the JEMRA meeting includes Jeff Farber, full professor in the Department of Food Science at the University of Guelph; Catherine W. Donnelly, professor of Nutrition and Food Science at the University of Vermont and Elliot Ryser, professor in the Department of Food Science and Human Nutrition at Michigan State University.

Other specialists are Deon Mahoney, formerly of WHO, FAO and Food Standards Australia New Zealand; Alexandre Leclercq, deputy director of the French Reference Centre and WHO Collaborating Centre Listeria at Institut Pasteur in Paris and Qingli Dong, professor and doctoral supervisor of the University of Shanghai for Science and Technology.

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