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Listeria, a dangerous pathogen out of control

Listeria monocytogenes it is a dangerous pathogenic bacterium, with high hospitalization and mortality rates, still underestimated. Or worse, out of control. In Italy – where Listeria is the cause of 12% of food safety alerts – but also in Europe, as shown by the RASFF reports and 'One Health'. A deepening.

1) Listeria, introduction

Pathogenic bacterium Gram-positive (such as Bacillus spp.., Clostridium botulinum C. perfringensEnterococcus, Mycobacterium bovis, Staphylococcus aureus, Streptococcus spp.), Listeria monocytogenes has exclusive alimentary transmission (WHO, 2015). Thirteen serotypes are known, three of which (1/2a, 1/2b, 4b) are associated with most foodborne infections.

'L. monocytogenes it is resistant. It tolerates salt and, unlike many other pathogens, can not only survive but also grow at temperatures below +1°C. It is thus also distinguished by its persistence in food production environments. The bacterium is ubiquitous in the environment and is found in moist environments, soil and decaying vegetation' (FDA, 2012). (1)

2) Listeriosis

The diffusion di Listeria is relatively low, compared to other bacteria (eg. Salmonella subsp.CampylobacterEscherichia coli spp.). Nonetheless, this bacterium is a major cause of premature mortality from foodborne illnesses. The infection from Listeria can cause two forms of disease:

- acute febrile gastroenteritis. It can manifest itself with various symptoms (nausea, vomiting, pain, fever, sometimes even diarrhea), from mild to intense. It usually resolves in young, healthy people. The same is not true for the vulnerable ones, which may incur the

– invasive or systemic listeriosis. The infection manifests itself with subtle symptoms (e.g. fever, diarrhoea) which are followed, even after a long incubation (up to 90 days), by septicemia or infections of the nervous system (meningitis) and various complications, even lethal.

2.1) Population groups at risk

Seniors – rapidly growing segment of the population in the Old Continent (1 out of 4 in Italy), and more – they are particularly vulnerable to Listeria monocytogenes. So the pregnant women, with a high risk of fetal and unborn child deaths, as well as i children in preschool age.

People with a weak immune system are more vulnerable – ie people with AIDS or other chronic diseases including diabetes, people taking immunosuppressive drugs (including chemotherapy and cortisone) following transplants, cancer, arthritis and other conditions – are also at risk of contracting systemic listeriosis (1,2,3).

3) Listeria monocytogenes and food safety. The situation in Italy

12% of recalls for food safety risks registered on the site websites of the Italian Ministry of Health, in the last twenty months, concerns contaminations by Listeria monocytogenes. The 63 alerts out of a total of 535, it should be noted, also affect industrial giants which thus demonstrate unacceptable lack of self-control, in spite of billionaire turnovers. Below is a review of the cases recorded between 1 January 2022 and 15 August 2023, broken down by food category. (4)

3.1) Meat, meat preparations and meat-based products

64% of alerts per Listeria examined in Italy (40 cases out of 63) concerned meat, meat preparations and meat-based products. At the top of the list is the AIA – Veronesi group (€ 6,5 billion euros in turnover, 8.500 employees), with 9 opaque recalls in Italy on sausage of chicken and turkey (5,6). The Veroni group also stands out (280 employees in Italy and 70 in the USA, where it is leader Italian in the cold cuts sector and was acquired in 2023 by SugarCreek Packing), with the mortadella super-giant in slices (7 calls). Listeria in the mortadella and in the pork bowl of Jomi SpA, as well as in baked ham high quality of Motta Srl.

Six alerts per Listeria they concerned i salamimainly from small and medium-sized enterprises. To the Felino DOP salami you add the Parma ham DOP, in a mixed appetizer of Brendolan Service Srl. Also contaminate the porchetta from Ariccia IGP (Prosciuttificio San Michele, Parmafood Group), the salty baconhorse rags del Veneto (also sold as 'good flavors of Tuscany'), beef and chicken (17 recalls in total). There bovine meat fresh has itself been subject to recalls for contamination from Listeria monocytogenesby Juvica Srl (scottona tartare) and Piatti Freschi Italia SpA (veal with tuna sauce).

3.2) Cheeses

The cheeses are in second place for the number of recalls in Italy caused by Listeria in the period examined, with 11 alerts out of 63 (17% of the total). Stand out the leader Italian in the production of gorgonzola PDO, Igor Srl, with two recalls followed by a third from another small producer. Followed by Emilio Mauri SpA, with two references on Taleggio cheese also in the PDO version (where it is not specified the pathogen). Other cheeses recalled for contamination by Listeria I'm a 'cheese of the cheesemaker' a semi-cooked (or semi-raw) paste, mozzarella cheese Piacenza, 'drunk from Treviso', pecorino cheese aretino with truffle. Maybe even afirst sale' from (no longer) raw milk, with pathogen once again Undeclared.

3.3) Fish products

The smoked salmon – at the top of the international rankings of fish products contaminated by Listeria monocytogenes – was subject to only one recall in Italy, in the period examined, in relation to a product arriving from Scotland. Another recall involved a cod-based preparation from Denmark, and a third involved frozen tropical prawns from Vietnam. The opportunity is worth remembering how frozen products are not exempt from food safety risks due to contamination from Listeria. (7)

3.4) Other foods

Ready-To-Eat foods (RTE) they are foods typically at risk of contamination from Listeria monocytogenes. In the period examined, the Ministry of Health recorded only three recalls in Italy Sandwich, with salmon and mayonnaise and with horse tails.

It deserves attention about the umpteenth omission of citation of the pathogen, by the leader of the supply to HoReCa in the Triveneto area (Bertolini group Srl, part of CH&F Bertolini).

A sauce with tuna and radicchio with Listeria cost four recalls to the Venetian Cucina Nostrana Srl. Finally aRussian salad, which involved a micro-enterprise from Lazio, and a pancake chocolate made in France.

4) Listeria and food safety in Europe. Under-reporting

16% of notifications on pathogenic microorganisms in food and 17% of the outbreaks of infection reported to Rapid Alert System on Food and Feed (RASFF), in the year 2022, concern Listeria monocytogenes.(8) But the alerts recorded on the RASFF represent the tip of theiceberg, as has already been observed. (9) The 132 notifications of contamination and the 7 outbreaks of L. monocytogenes in fact, they do not include the majority of recalls registered at national level, in Italy and in the other 26 member countries.

Under-reporting. The incomplete scenario offered by the RASFF report did not allow EFSA and ECDC (European Center for Disease Prevention and Control) to fully evaluate the opportunity of a shared action on Listeria, a pathogen tragically more dangerous than Salmonella. Thus, in 2022, four Rapid Outbreak Assessment (ROA) and a Joint Notification Summary (JNS) have been dedicated to Salmonella spp.. but no one to Listeria monocytogenes.

4.1) EFSA - ECDC report on zoonoses

'EU One Health Zoonoses Summary Report' (EUOHZ), published by EFSA (European Food Safety Authority) and ECDC (European Center for Disease Control and Prevention), provides and interprets key statistics on monitoring and surveillance activities on zoonoses and zoonotic agents in humans, food, animals and feed. (10)

The latest report EUOHZ – presenting analyzes conducted in 2021 in 27 Member States plus the United Kingdom (Northern Ireland alone), the three EFTA participating States (European Free Trade Association. Iceland, Norway, Switzerland and Liechtenstein) and the four pre-accession countries (Albania, Bosnia-Herzegovina, Republic of North Macedonia, Montenegro and Serbia) – confirms the problem of under-reporting. (11)

4.2) Listeria in Europe. The numbers don't add up

24 Member States reported the results of the analyses Lysteria monocytogenes performed in 2021 on a total of 244.357 samples of different food categories Ready-To-Eat (RTE), picked up'from farm to fork":

– the highest values ​​(contaminations on 2-5% of the samples) were observed on fish and fishery products, beef and pork products, fruit and vegetables, sheep's milk cheeses. 2,3% the average rate of contamination on 40.710 samples of meat and meat-based products,

- at the level of retail, the highest contamination rates were observed in 'meat products, fermented sausages' (3,1%) and 'fish' (1,5%),

– at production, the highest contamination indices were observed on 'fishery products' (3,1%), 'products of meat origin other than fermented sausages' (2,5%) and fish (1,8 %),

– in primary agricultural production, the absence of minimum legal requirements for harmonized sampling and reporting made it impossible to collect sufficient data.

Contamination rates of the samples analyzed – to be considered together with the volumes of the categories of risky foods placed on the EU market – have an order of magnitude well higher than the numbers of notifications in the RASFF system, as we wanted to demonstrate.

4.3) Listeriosis in Europe. The numbers don't add up

'In 2021, the greatest number of deaths were associated with listeriosis (N = 196; 13,7%), followed by salmonellosis (N = 71; 0,18%) and STEC infections (N = 18; 0,41%)' (EFSA-ECDC, EU One Health Zoonoses Summary Report 2021).

2.183 human cases of invasive or systemic listeriosis were ascertained in 2021, of which 1.482 in the European Union. In a context of under-reporting which is structural in at least half of the countries, as well as in the RASFF system:

– only 16 out of 35 states were able to provide clinical data on 956 of the aforementioned cases (43,8%), reporting a hospitalization rate of 96,5%. And only 14 countries have reported 196 deaths, out of 1.457 confirmed cases (65,4%. See notes 12,13),

– Vice versa, EFSA has become aware of 23 outbreaks of listeriosis (compared to 4 recorded in the RASFF report 2021), only 104 cases and 12 deaths. The numbers don't add up.

5) Provisional conclusions

A serious risk of food safety afflicts Europe and is still systematically underestimated by the institutions (European Commission and Member States), the national authorities responsible for official controls, operators in the industry sectors and retail. Until?

Dario Dongo


(1) Bad Bug Book. Handbook of Foodborne Pathogenic Microorganisms and Natural Toxins. 2nd edition (2012). FDA (Food and Drug Administration), USA. Pages 99-102

(2) Listeria. Maladie – Recommendations CNR Listériose. Institute Pasteur

(3) Silvia Bonardi, Dario Dongo. Listeria and listeriosis, an in-depth study. GIFT (Great Italian Food Trade).

(4) Ministry of Health of the Italian Republic. Food recalls by operators

(5) Dario Dongo. Listeria in AIA frankfurters, false accusations against Asiago cheese. GIFT (Great Italian Food Trade).

(6) The question remains how the Ministry of Health (DGISAN, Office 8) can publish product recalls with undeclared pathogens. Combination, by a giant like the Veronese group and various other industries

(7) Silvia Bonardi, Dario Dongo. Listeria and frozen vegetables, here's why. GIFT (Great Italian Food Trade).

(8) 2022 Annual Report – Alert and Cooperation Network. European Commission. doi:10.2875/941288. See paragraphs 3.1.3, 3.1.4

(9) Dario Dongo, Marta Singed. RASFF 2022, EU food safety report. GIFT (Great Italian Food Trade).

(10) Since 2020, the production of the EUOHZ annual report is supported by the ZOE Consortium (Zoonoses under a One health perspective in the EU) composed of the Istituto Superiore di Sanità (ISS. Rome, Italy), the Experimental Zooprophylactic Institute of the Venezie (Padua, Italy), the French Agency for food, environmental and occupational health and safety (Maisons- Alfort, France), the Experimental Zooprophylactic Institute of Abruzzo and Molise (Teramo, Italy) and the Experimental Zooprophylactic Institute of Lombardy and Emilia Romagna (Brescia, Italy), under the coordination of the Experimental Zooprophylactic Institute of the Abruzzo and Molise (Teramo, Italy)

(11) The European Union One Health 2021 Zoonoses Report. EFSA, ECDC. EFSAJournal / Volume 20, Issue 12 / e07666.

(12) In 2021, the highest notification rates were observed in Finland, Denmark, Sweden and Slovenia, with 1,3, 1,1, 1,0 and 0,9 cases per 100.000 population, respectively. The lowest notification rates were reported by Bulgaria, Croatia, Cyprus, Greece and Romania (≤0,20 per 100.000). Italy is still in the low area of ​​the ranking, with 0,41 cases per 100.000 inhabitants (241 cases in total), albeit an improvement compared to previous years (0,29 cases per 100.000 inhabitants, 178 in total, compared to 2018)

(13) France reported the highest number of deaths (75), followed by Spain (34), Poland (25) and Germany (20). Infections from Listeria monocytogenes were mostly reported in the age group over 64 years. At the European level, the percentage of listeriosis cases in this age group has increased steadily, from 56,1% in 2008 to 64,5% in 2019 and 72,5% in 2020

(14) Dario Dongo. USA and Canada, the biggest call of 2018 in silence. GIFT (Great Italian Food Trade).

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Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.

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