Monitoring Ready-to-Eat Foods Contamination by Listeria monocytogenes in France

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1 Monitoring Ready-to-Eat Foods Contamination by Listeria monocytogenes in France M. SANAA, G. ZANELLA O. CERF

2 Objectives Quantify the levels of Lm in certain foods in order to estimate consumer exposure to the Listeria monocytogenes Conduct an assessment of the relative risk of listeriosis associated with various types of RTE foods

3 DATA Continuing Survey of Food Intakes by Individuals (AFSSA/CRÉDOC/DGAL, INCA survey Monitoring LM contamination of ready-to-eat foods (DGCCRF )

4 Samples from 1993 to 2001

5 Prevalence of Lm Foods from Caterer Seafood Blood pudding, small chitterling sausage Delicatessen (tongue, head) Rillettes Smoked fish Ripened soft cheese Ripened soft cheese, washed rind Germinated seeds 14% 12% 10% 8% Year N Obs Percent % 4% 2% 0%

6 Prevalence of LM by food categories 1993 to % 50% 40% 30% 20% 10% 0% Delicatessen (tongue, head) Hot dog, Merguez, Chipolatas Lardons Freezed minced meat Minced meat Smoked fish Ripened soft cheese Ham Boiled ham Baked meat Rillettes Freezed fish Blood pudding, small chitterling sausage Ripened soft cheese, washed rind Fish Freezed vegetables Hamburger Pate Seafood Germinated seeds Fresh cream, milk Pastries Foods from Caterer Sausage semi-hard cheese Pasteurised Ripened soft cheese, washed rind Pasteurised Ripened soft cheese Hard, gratting cheese Pasteurised goat or ewe cheese Goat or Ewe cheese Blue-veined cheese Cottage cheese, Ice cream Salad Fruit juce

7 Prevalence of LM by food categories 1997 to % 14% 12% 10% 8% 6% 4% 2% 0% Smoked fish Delicatessen (tongue, head) Germinated seeds Blood pudding, small chitterling sausage Foods from Caterer Seafood Rillettes Ripened soft cheese, washed rind Ripened soft cheese

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10 Foods from Caterer Seafood Blood pudding, small chitterling sausage Delicatessen (tongue, head) Rillettes Smoked fish Ripened soft cheese Ripened soft cheese, washed rind Germinated seeds

11 Food consumption (INCA) Women years old Foods Mean (g) STD Minimum Maximum Ripened Soft cheese (n=477) Ripened soft cheese, washed rind (n=477) Delicatessen (tongue, head) (n=3)* Blood pudding, small chitterling sausage (n=27) Rillettes (n=9)* Smoked fish (n=477) Seafood (n=477) Foods from Catere (salads) (n=477)

12 Prevalence pi ~ Beta Mean of log 10 concentration mi ~ Normal STD of log 10 concentration stdi ~ χ 2 Ri (discrete distribution) Assessment of relative risks Individual intakes One serving qj ~ Distribution Dosej = Distr. concentration x qj Risk per serving : Risquej = [(1- (1- Ri) Dosej ]*pi i iterations Relation dose-response (pregnant women) Distribution of risk per serving Mean of risks per iteration (Rm) Descending Rank of foods per iteration Foods ranking Using mean of ranks

13 Monte Carlo Ranking Ripened soft cheese Delicatessen (tongue, head) Seafood Foods from Caterer (Salads)

14 Ranking ( ) Rank Food categories Ripened Soft cheese Pasteurized Ripened Soft cheese, washed rind Ripened Soft cheese, washed rind Pasteurized Ripened Soft cheese Blood pudding, small chitterling sausage Hard cheese Germinated seeds Smoked fish Rillettes Cooked vegetables Delicatessen (tongue, head) Seafood Foods from Caterer (Salads)

15 Ranking ( ) Rank Food categories Ripened Soft cheese Rillettes Ripened Soft cheese, washed rind Blood pudding, small chitterling sausage Delicatessen (tongue, head) Smoked fish Germinated seeds Foods from Caterer (Cooked) Seafood Foods from Caterer (uncooked)

16 Discussion Are samples representative? Sampling frame (Not random) Bias: over estimation of number of LM? Analysis by food categories Small Sample Size regarding to the prevalence of food contaminated with > 100 CFU/g Intake surveys (quantity, frequency, seasonality) Next step: take into account consumption frequency and redo Relative ranking and bayesian appoach.

17 Acknowledgements Providing Data DGCCRF, Olivier Pierre AFSSA, INCA