Listeria monocytogenes in food as public safety risk European Symposium on Food Safety 21-23 May 2012 Listeria monocytogenes in food as public safety risk Grzegorz Madajczak, Ph.D. DVM gmadajczak@pzh.gov.pl

The goal of this presentation: Present, that Listeria monocytogenes it is not only the food quality / safety criterion, but first of all public health risk.

Listeria monocytogenes Gram(+) bacteria. Regular, short rods with rounded ends. Facultative anaerobes. Can grow at refrigeration temeratures to significant numbers (in sufficient time). Resistant for low pH. The image source: http://www.sciencephoto.com/

Listeria monocytogenes The primary reservoir for L. monocytogenes is soil, water and forage, mud, and silage. Additional reservoir is alimentary tract of domestic and wild animals. Source of bacteria are infected animals. Consumption of contaminated food is main route of infection for human. Infectious dose was determined as 107 CFU. Other papers suggest even 100 CFU. The image source: http://emedicine.medscape.com/article/965841-overview

Listeriosis Infectious disease, caused by Listeria monocytogens. Especially danger for some groups of people (high risk groups): Neonates, Pregnant women, Immunocompromised people, Elderly (60.2 % of cases in 2010 occurring in individuals over the age of 65).

Age and gender distribution of listeriosis High number of pregnancy associated cases Data Source: ECDC TESSY

Transmission of L. monocytogenes Reservoir Source Vehicle Transplacentar infections

L. monocytogenes in food procesing and retail L. monocytogenes is frequently present in raw foods of both plant and animal origin. Can be endemic in food processing environment. Present in food retail environment and houshold. “From farm to fork”

Invasive listeriosis Notificable disease. Varied clinical forms are described: Sepsis, CNS infections, Endocarditis, Localised infections, Pregnancy associated infections

Gastrointestinal listeriosis Usually self-limiting febrile gastrointestinal disease presenting with unspecific symptoms like: Nausea, Vomiting, Diarrhea. Observed as sporadic cases and food-poisoning outbreaks.

Sporadic Listeria Gastroenteritis ? Study conducted by Walter F. Schlech III in 2002 in Canada. Material: stool spec. from 7775 diarrhea cases. Only 18 cases were caused by L. monocytogenes. L. monocytogenes could cause the sporadic gastroeteritis, but it is not importanant pathogen in such cases. Schlech et al., CID 41 (2005), 778-784

Outbreaks of listeriosis Food-borne outbreak: „an incidence, observed under given circumstances, of two or more human cases of the same disease and/or infection, or a situation in which the observed number of human cases exceeds the expected number and where the cases are linked, or are probably linked, to the same food source”. (Directive 2003/99/EC) Food vehicle: food (or foodstuff) that is contaminated by a causative agent. (EFSA, Manual for reporting of food-borne outbreaks […])

Outbreaks of listeriosis Listeria monocytogenes is absolute foodborne pathogen, caused both: gastrointestinal and invasive listeriosis. All listeriosis outbreaks should be classified as foodborne or at least waterborne.

Outbreaks of listeriosis Country Year Food vehicle Affected France 1999-2000 Pork tongue in jelly 26 cases USA (multistate) 2008-2009 Mexican-style cheese made from pasteurized milk 8 pregnant women Czech Rep. 2006 Local cheese 75 cases Canada, Quebec 2008 Pasteurized milk cheese 14 pregnant women, 2 babies born to asymptomatic carriers Austria, Germany, Czech Rep. 2009 Acid curd cheese “Quargel” 14 cases, 4 deaths USA, Louisiana 2010 Hog head cheese 14 cases of invasive listeriosis 2011 Cantaloupe (Rockmelon) 84 people, 15 deads In 2012 year 37 alerts were notified in RASFF In 2011 year 106 alerts were notified in RASFF

Pregnancy associated listeriosis Case classification: illness occurred in a pregnant woman or an infant aged <28 days. Woman has unspecific flu-like symptoms. CNS infection are very rare in pregnant women. Outcome depends on stage of pregnancy. I trimester II trimester III trimester Congenital listeriossis Preterm birth Stillbirth Miscarriage

Congentital listeriosis Depending on time of clinical symptoms manifestation, two types of infection are recognized Early-onset Late-onset Associated with prematurity and acquired throw utero. Caused by bacteria acquired from vaginal tract of asymptomatic mothers Clinical symptoms occurs just after birth (mean-time is 1.5 day) Occurs about 2 weeks post partum. Sepsis Meningitis

Severity of listeriosis Characterization of listeriosis severity depends on category of disease (invasive / non-invasive). Low occurrence contrasts with high case-fatality rate (ranging 20-30%). Up to 11% of neonates and 30% survivor of CNS infections suffer residual symptoms. Psychiatric squeals have been also reported. Also psychological aspects Losing pregnancy Neonatal deaths

Listeriosis in Europe

Listeriosis in Europe The EU/EEA rate of confirmed human cases of Listeria infection has been relatively stable in the last four years. Listeriosis had the highest impact among the elderly (65+) with the highest confirmed case rates and high mortality. Data Source: ECDC TESSY

Listeriosis in Europe Listeriosis cases in 2010 by country Data Source: ECDC TESSY

Listeriosis in Poland Listeriosis cases Neonatal listeriosis Data Source: Infectious diseases and poisonings in Poland http://www.pzh.gov.pl/oldpage/epimeld

Listeria monocytogenes – food safety criterions EU Regulation No 2073/2005 lays down food safety criteria for L. monocytogenes in RTE foods: In RTE food for infants and special medical purposes L. monocytogenes must not be present in 25 g, L. monocytogenes must not be present in levels above 100 cfu/g during the shelf life of other RTE products.

Listeria monocytogenes – food safety criterions RTE foods that NOT SUPPORT the growth of the bacterium L. monocytogenes must not be present in levels above 100 cfu/g during the shelf life.

Listeria monocytogenes – food safety criterions RTE foods that SUPPORT the growth of the bacterium L. monocytogenes must not be present in 25 g at the time of leaving the production plant; however, if the producer can demonstrate, that the product will not exceed the limit of 100 cfu/g throughout shelf life this criterion does not apply.

USA FSIS L. monocytogenes “zero tolerance” politic in RTE Formed as result of increased number of listeriosis in 1980-90’s in USA after consumption of deli meats and other processed products. Zero tolerance - no detectable level of L. monocytogenes in RTE food products permitted. One of long-term initiatives was to conduct a risk assessment for L. monocytogenes together with FDA.

Risk assessment to public health from foodborne L. monocytogenes The goal was to predict the relative public health impact of foodborne Listeria monocytogenes from selected 23 food categories. RTE foods to asses were chosen, if had a history of either Listeria monocytogenes contamination or were implicated epidemiologically. This risk assessment have been used as base for FAO WHO reccomendations.

Risk assessment - results Decreased Risk per Annum Deli Meats Frankfurters (not reheated) No food categories Deli-type Salads Dry/Semi-dry Fermented Sausages Frankfurters (reheated) Fresh Soft Cheese Fruits Semi-soft Cheese Soft Ripened Cheese Vegetables Cooked RTE Crustaceans High Fat and Other Dairy Products Pasteurized Fluid Milk Soft Unripened Cheese Pâté and Meat Spreads Unpasteurized Fluid Milk Smoked Seafood Decreased Risk per Serving Preserved Fish Raw Seafood No food categories Cultured Milk Products Hard Cheese Ice Cream and Other Frozen Dairy Products Processed Cheese Very high risk High risk Moderate risk Low risk Very low risk

Foods of very high risk Includes two food categories: Deli Meats, Frankfurters, Not Reheated. They have high predicted relative risk rankings on both a per serving and per annum basis, because: Have relatively high rates of contamination. Support the relative rapid growth of Listeria monocytogenes under refrigerated storage. Are stored for extended periods. Are consumed extensively. These products have also been directly linked to outbreaks of listeriosis. This risk designation is one that is consistent with the need for immediate attention in relation to the national goal for reducing the incidence of foodborne listeriosis. Likely activities include the development of new control strategies and/or consumer education programs suitable for these products.

Very low risk food products Includes four food categories: Cultured Milk Products, Hard Cheese, Ice Cream and Other Frozen Dairy Products, Processed Cheese. These products all have in common the characteristics of being subjected to a bactericidal treatment, having very low contamination rates, and possessing an inherent characteristic that either inactivates Listeria monocytogenes (e.g., Cultured Milk Products, Hard Cheese) or prevents its growth (e.g., Ice Cream and Other Frozen Dairy Products, Processed Cheese). This results in a very low predicted per serving relative risks. The predicted per annum relative risks are also low despite the fact that these products are among the more commonly consumed RTE products considered by the risk assessment. The results of the risk assessment predict that unless there was a gross error in their manufacture, these products are highly unlikely to be a significant source of foodborne listeriosis.

EU initiative for L. monocytogenes reduction in RTE foods European Comission launched the survey on Listeria monocytogenes in selected categories of ready-to-eat food at retail in the EU. RTE food categories under investigation: Smoked and gravad fish, Soft and semi-soft cheeses, Heat-treated meat products. Analyses methods: L. monocytogenes detection and enumeration, pH and aw measurement,

Reduction of risk to public health from foodborne L. monocytogenes

Summary Listeriosis is serious infectious foodborne disease. Many factors affect on risk of listeriosis. Food producers have not influence on many of them. Initial quality of food - no Listeria at detectable level is the best method to increase the food safety.

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