Transfer and survival of Campylobacter in the consumer phase Bjarke Christensen, Helle Sommer, Niels Nielsen, Hanne Rosenquist and Birgit Nørrung. Danish Veterinary and Food Administration Division of Microbiological Safety

Objectives Performing a quantitative risk assessment provides: an overview of the spread of Campylobacter from ‘slaughterhouse to consumer’ an overview of the data availability, data gaps etc. An idea about the relative importance of different steps at the production, retail and consumer level on the risk of getting ill after consumption of a chicken serving Mitigation strategies (relative risk estimates) An estimate Provide guidelines to set up risk management options

Consider the following strategies: - Reduce flock prevalence - Reduce numbers on chicken carcasses - Improve kitchen hygiene - Young adults are at higher risk - Logistic slaughter problably not important. Outcome of the Danish risk asssessment - Reduce numbers on chicken carcasses

Raw chickenMeal Numbers: Freguencies: Hygiene Consumer Size of meal Meals ingested Microorganism Individuals Transfer/survival Preparation and consumption of meals

Ready-to-eat food (salad, bread etc.) Raw chicken Heat treatment- Hands Cutting board, Utensils etc. Transfer and survival in the kitchen environment Exposure Storage

Fraction transferred (k) Numbers transferred depends on mechanical parameters: e.g. liquids excreted size of contact areas. May vary significantly from one handling event to the next. For some processes the distribution may be broad and for others relatively narrow. Frequency (f) Depends on status of individuals Hygiene habits Frequency of preparing a meal

f 1 ·k 1 f 2 ·k 2 · f x ·k x · f n-1 ·k n-1 f n ·k n Dose in meal Numbers on chicken Preparation processes

Hygiene Bad Not washing cutting board f ncb ·k ncb Better Washing cutting board, but using same cutting board f cb ·k cb Less frequent, but high transfer rate More frequent, but low transfer rate Log10 fraction transferred k ncb Log10 fraction transferred k cb

f 1 ·k 1 f 2 ·k 2 · f x ·k x · f n-1 ·k n-1 f n ·k n Dose in meal Numbers on chicken Preparation processes F·K

Reduce number of Campylobacters on chicken carcasses

Effect of reducing Campylobacter load on raw chicken products Campylobacter load on raw chicken (Log10 cfu/chicken) Relative change in positive meals Number of Campylobacters per meal (log10 cfu) K transfer Log10 fraction transferred Change on chickens (Log10 cfu/chicken)

Effect of reducing Campylobacter load on raw chicken products Log10 fraction transferred Change on chickens (Log10 cfu/chicken) Log10 fraction transferred Change on chickens (Log10 cfu/chicken)

Changing accetable minimum load in a meal Change on chickens (Log10 cfu/chicken) Log10 fraction transferred Change on chickens (Log10 cfu/chicken)Log10 fraction transferred

Guidelines to risk managers: Reduction strategies can be very efficient But: The effect will be less efficient in cases with extremely bad kitchen hygiene (High transfer rate) Significant effect for good, but not perfect hygiene (Medium transfer rate) Less efficient for highly susceptible people

Conclusions Combine reduction strategy with education Data gap: Preparation habits related to incidence. Quantitative measures on raw products not enough True estimates not considered Major disadvantage: Do not produce safe meals in a controlable manner

Mean: –4.08 Mean: –5.00 K transfer Resulting K transfer

Prevalence of positive meals Log10 fraction transferred k high  f low k low  f high

Quantitative transfer DATA Chen et al. (2001) Zhao et al. (1998)

Preparation hygiene in private kitchens (Yang et al. 1998)

Consumption patterns Use of diatary surveys Food preferences Size of meals Where is the food ingested –Restaurants –At home Who prepare the food Sub populations –Age –Gender –Ethnic –Education

Link between consumer and person preparing the food in private homes Preparation (preparer) Consumer Kitchen hygiene Who prepare the food Chicken meals ingested Meals ingested at home ? Household types Depends on Number, Age and gender of adults in household

DATA (I) The consumer Frequency of ingesting chicken meals Frequency of ingesting meals at home Household/family relationships –Who prepare the food –Who prepare for who Family/household types Family size

DATA (II) Danish Dietary Survey (Andersen et el. 1996) National demographic data (Statistics Denmark)

Results Frequency of ingesting chicken meals at home where the cutting board has not been washed

Pointer der skal frem: Hovedformål er at give guidelines til risk managers Estimater er ikke vigtige Det samlede antal sygdomstilfælde er kendt/fixeret. D.v.s. hvis f høj så er k lav og omvendt F høj k lav  mindre effekt ved at reducere antal på carcass F lav k høj  stor effekt ved at reducere antal på carcass