Campylobacter contamination and the relative risk of illness from organic broiler meat in comparison with conventional broiler meat.

Danish organic broiler meat, represented by carcasses sampled at the end of processing after chilling, was more frequently contaminated with thermotolerant Campylobacter spp. than conventional broiler carcasses; the yearly mean prevalence being 54.2% (CI: 40.9-67.5) for organic and 19.7% (CI: 14.8-24.7) for conventional carcasses. Campylobacter jejuni was the most frequently isolated species. The difference in prevalence was obvious in all quarters of the year. Contamination of organic and conventional broiler carcasses was more likely to occur in the warmer summer months, in this case in the third quarter, as also documented for conventional broiler flocks. When contaminated, the mean concentration of Campylobacter on neck skin samples of organic and conventional carcasses was not significantly different (P=0.428); 2.0±0.65 log 10 cfu/g and 2.1±0.93 log 10 cfu/g, respectively. Assessing the relative risk of becoming ill following exposure to Campylobacter on conventional or organic broiler meat indicated that the risk per serving from organic carcasses was 1.7 times higher than that of conventional carcasses. The higher risk of illness from organic broiler carcasses compared with conventional broiler carcasses emphasizes the importance of implementing control measures in organic broiler production.

Human risk from thermotolerant Campylobacter on broiler meat in Denmark.

This paper describes a new approach by which changes over time in the relative risk of human campylobacteriosis from broiler meat are evaluated through quantitative microbiological risk assessment modelling. Danish surveillance data collected at retail from 2001 to 2010 on numbers of thermotolerant Campylobacter spp. on Danish produced and imported chilled and frozen broiler meat were the basis for the investigation. The aim was to explore if the risk from the different meat categories had changed over time as a consequence of implemented intervention strategies. The results showed a slight decrease from 2005 to 2008 in the human risk from Danish produced broiler meat, and a decrease from 2005 to 2010 in the risk from imported chilled meat. This risk reduction coincides with control measures implemented to reduce Campylobacter in Danish and imported chilled broiler meat. The human risk of campylobacteriosis from Danish frozen meat increased but remained lower compared to chilled meat. In total, the relative risk from broiler meat available for sale in Denmark increased from 2001 to 2005 after which the risk decreased to a level similar to the period 2001-2002. The use of QMRA in the evaluation of intervention strategies based on monitoring data provided an added value, compared to the traditional approach of only using changes in prevalence. The estimated human health risk is a function of prevalence and the distribution of concentrations, and therefore takes best usage of the available data, while providing the most relevant outcome for food safety risk managers.

Seasonal influence on the prevalence of thermotolerant Campylobacter in retail broiler meat in Denmark.

In Denmark, the incidence of human campylobacteriosis cases, as well as the Campylobacter prevalence in broiler flocks, is strongly influenced by season with a summer peak in July-August. Therefore, it was considered that the prevalence of Campylobacter in broiler meat sold at retail in Denmark might also be influenced by season. A retrospective survey analysis was performed on 2001-2007 national surveillance data of the prevalence of thermotolerant Campylobacter in all conventional broiler flocks at slaughter, and in randomly sampled broiler meat at retail. There was a significant effect of season on the occurrence of Campylobacter in meat at retail; the largest effect was found for domestic chilled meat. Thus, the Campylobacter prevalence in Danish broiler flocks, which fluctuated with season, was found to be a strong predictor for the occurrence of Campylobacter in fresh, chilled, Danish broiler meat. However, besides flock prevalence, there was also a direct effect of season on the occurrence of Campylobacter in Danish broiler meat at retail.

Effect of organic acids and marination ingredients on the survival of Campylobacter jejuni on meat.

The aim of this study was to determine whether marination of chicken meat in different food ingredients can be used to reduce populations of Campylobacter jejuni. C. jejuni strains were exposed to different organic acids (tartaric, acetic, lactic, malic, and citric acids) and food marinating ingredients at 4 degrees C in broth and on chicken meat. The organic acids (0.5%) reduced populations of C. jejuni in broth (chicken juice and brain heart infusion broth) by 4 to 6 log units (after 24 h); tartaric acid was the most efficient treatment. Large strain variation was observed among 14 C. jejuni isolates inoculated in brain heart infusion broth containing 0.3% tartaric acid. On chicken meat medallions, reductions of C. jejuni were 0.5 to 2 log units when tartaric acid solutions (2, 4, 6, and 10%) were spread onto the meat. Analysis of acidic food ingredient (e.g., vinegar, lemon juice, pomegranate syrup, and soya sauce) revealed that such ingredients reduced counts of C. jejuni by at least 0.8 log units on meat medallions. Three low pH marinades (pH < 3) based on pomegranate syrup, lemon juice, and white wine vinegar were prepared. When applied to whole filets, these marinades resulted in a reduction of approximately 1.2 log units after 3 days of storage. Taste evaluations of chicken meat that had been marinated and then fried were graded positively for flavor and texture. Thus, success was achieved in creating a marinade with an acceptable taste that reduced the counts of C. jejuni.

Chemical decontamination of Campylobacter jejuni on chicken skin and meat.

This study evaluated the effectiveness of 11 chemical compounds to reduce Campylobacter jejuni on chicken skin and meat samples dipped in chemical solutions. Treatment of skin samples for 1 min using tartaric acid (2%) and caprylic acid sodium salt (5%) caused reductions of C. jejuni NCTC11168, which were not significantly different from the reduction obtained by sterile water (0.95 log). Statistically larger reductions (1.57 to 3.81 log) were caused by formic acid (2%), lactic acid (2.5%), trisodium phosphate (10%), capric acid sodium salt (5%), grapefruit seed extract (1.6%), and chlorhexidine diacetate salt hydrate (1%). The most effective compounds were cetylpyridinium chloride (0.5%) and benzalkonium chloride (1%) (>4.2 log). However, when these treated samples were stored for 24 h at 5 degrees C, cetylpyridinium chloride, benzalkonium chloride, and grapefruit seed extract were less effective, indicating that some cells may recover after a 1-min treatment with these chemicals. An increase in treatment time to 15 min resulted in higher effectiveness of trisodium phosphate and formic acid. Interestingly, when reduction of the C. jejuni population was compared on chicken skin and meat, sterile water and lactic acid caused considerably larger reductions on skin than on meat, whereas the opposite was seen for caprylic acid sodium salt. In conclusion, this study has identified chemicals with substantial reduction effects on C. jejuni. The analysis has further emphasized that treatment time and food matrix affect the outcome in an unpredictable manner and, therefore, detailed studies are needed to evaluate the reduction effectiveness of chemicals.

Reduction of thermotolerant Campylobacter species on broiler carcasses following physical decontamination at slaughter.

To reduce the incidences of human Campylobacter infections, a number of countries are investigating methods for reducing human exposure to Campylobacter from broiler meat. In addition to implementing biosecurity measures at the farm, Campylobacter may be controlled by reducing Campylobacter counts through physical decontamination of the meat. The current study was conducted to compare the Campylobacter-reducing ability of three physical decontamination techniques, forced air chilling, crust freezing, and steam-ultrasound, performed in the plant with naturally contaminated broiler chickens. The effects of all three techniques were evaluated and compared with the effect of freezing. Mean reductions obtained were 0.44 log CFU per carcass, 0.42 log CFU per sample, and > or = 2.51 log CFU per carcass, respectively. All techniques resulted in significant reductions of the Campylobacter concentration on the carcasses (P < 0.05). However, none of the techniques were as effective as freezing based on reductions in Campylobacter counts and on adverse effects. The increase in Campylobacter counts on carcasses following visceral rupture during the evisceration operation also was examined. Visceral rupture resulted in an increase of 0.9 log CFU per carcass, suggesting that Campylobacter counts also may be reduced by optimizing the hygienic design of equipment or by physical removal of fecal contamination.

A comparison of risk assessments on Campylobacter in broiler meat.

In recent years, several quantitative risk assessments for Campylobacter in broiler meat have been developed to support risk managers in controlling this pathogen. The models encompass some or all of the consecutive stages in the broiler meat production chain: primary production, industrial processing, consumer food preparation, and the dose-response relationship. The modelling approaches vary between the models, and this has supported the progress of risk assessment as a research discipline. The risk assessments are not only used to assess the human incidence of campylobacteriosis due to contaminated broiler meat, but more importantly for analyses of the effects of control measures at different stages in the broiler meat production chain. This review paper provides a comparative overview of models developed in the United Kingdom, Denmark, the Netherlands and Germany, and aims to identify differences and similarities of these existing models. Risk assessments developed for FAO/WHO and in New Zealand are also briefly discussed. Although the dynamics of the existing models may differ substantially, there are some similar conclusions shared between all models. The continuous introduction of Campylobacter in flocks implies that monitoring for Campylobacter at the farm up to one week before slaughter may result in flocks that are falsely tested negative: once Campylobacter is established at the farm, the within-flock prevalence increases dramatically within a week. Consequently, at the point of slaughter, the prevalence is most likely to be either very low (<5%) or very high (>95%). In evaluating control strategies, all models find a negligible effect of logistic slaughter, the separate processing of positive and negative flocks. Also, all risk assessments conclude that the most effective intervention measures aim at reducing the Campylobacter concentration, rather than reducing the prevalence. During the stage where the consumer handles the food, cross-contamination is generally considered to be more relevant than undercooking. An important finding, shared by all, is that the tails of the distributions describing the variability in Campylobacter concentrations between meat products and meals determine the risks, not the mean values of those distributions. Although a unified model for risk assessment of Campylobacter in the broiler meat production would be desirable in order to promote a European harmonized approach, it is neither feasible nor desirable to merge the different models into one generic risk assessment model. The purpose of such a generic model has yet to be defined at a European level and the large variety in practices between countries, especially related to consumer food preparation and consumption, complicates a unified approach.

Characterization of Campylobacter phages including analysis of host range by selected Campylobacter Penner serotypes.

BACKGROUND: The predominant food borne pathogen in the western world today is Campylobacter. Campylobacter specific bacteriophages (phages) have been proposed as an alternative agent for reducing the burden of Campylobacter in broilers. One concern in relation to phage biocontrol is the narrow host range often displayed by phages. To identify the potential of phages as a Campylobacter reducing agent we needed to determine their infectivity on a panel of isolates representing the Campylobacter strains found in broilers as well as humans. RESULTS: In this study, Campylobacter phages were isolated from the intestines of broilers and ducks and from abattoir sewage. Twelve phages were investigated to determine their ability to infect the Campylobacter Penner serotypes commonly present in Danish poultry and patients with campylobacteriosis. A total of 89% of the Campylobacter jejuni strains and 14% of the Campylobacter coli strains could be infected by at least one of the bacteriophages. The majority of the phages infected the most common serotypes in Danish broilers (O:1,44; O:2; O:4-complex), but showed limited ability to infect 21 of the less frequent Campylobacter serotypes. Pulse field gel electrophoresis (PFGE) and restriction endonuclease analysis (REA) were used to characterize the phage genomes. Three categories of bacteriophages were observed. I: a genome size of approximately 194 kb and refractory to digestion with HhaI; II: a genome size of approximately 140 kb and digestible by HhaI; and III: a genome size undeterminable in PFGE. The categorization of the phages correlated with the host range patterns displayed by the phages. Six phages were subjected to transmission electron microscopy (TEM). They all belonged to the family of Myoviridae. CONCLUSION: We have characterized and identified the host range of 12 Danish Campylobacter phages. Due to their ability to infect the majority of the common serotypes in Denmark we suggest the phages can become an effective agent in the effort to reduce the incidence of campylobacteriosis in Denmark. This study provides the basis for future experiments in Campylobacter phages and knowledge for the selection of Campylobacter phages for biocontrol in broilers.

A collaborative study on a Nordic standard protocol for detection and enumeration of thermotolerant Campylobacter in food (NMKL 119, 3. Ed., 2007).

A Nordic standard protocol for detection and enumeration of thermotolerant Campylobacter in food has been elaborated (NMKL 119, 3. Ed., 2007). Performance and precision characteristics of this protocol were evaluated in a collaborative study with participation of 14 laboratories from seven European countries. The laboratories performed qualitative, semi-quantitative and quantitative analyses on samples of chicken meat, cut lettuce, and milk artificially inoculated with different concentrations including blank duplicates of one strain of Campylobacter coli (SLV-271) and one strain of Campylobacter jejuni (SLV-542). Expected concentrations (95% C.I.) (cfu g(-1) or ml(-1)) of both strains in matrices were 0.6-1.4 and 23-60 for qualitative detection, and 0.6-1.4; 23-60; and 420-1200 for semi-quantitative detection. For quantitative determination, the expected concentrations of C. jejuni/C. coli were 420-1200/580-1100; 2100-6000/6300-11,000; and 4100-11,000/53,000-97,000 cfu g(-1) or ml(-1). The qualitative and semi-quantitative techniques resulted in comparable detection. The overall specificity and sensitivity of the detection techniques was 98.6% (95% C.I.: 95.1-99.8%) and 82.8% (C.I.: 78.4-86.6%), respectively. The sensitivity was not influenced by food matrix (P=0.359), but was significantly lower for C. coli compared to C. jejuni (P=0.007) and for concentrations below 1.4 cfu g(-1) (P<0.001). The detection techniques were therefore only considered satisfactory for detection of Campylobacter concentrations above approximately 25 cfu g(-1) for all matrices tested, which was supported by calculation of values for accordance, concordance, and concordance odds ratio. No statistical difference was found between enumerations obtained by the semi-quantitative and quantitative techniques for comparable concentrations of Campylobacter (420-1200 cfu g(-1) or cfu ml(-1)) (P=0.104). Both techniques underestimated concentrations of thermotolerant Campylobacter in milk. The semi-quantitative technique estimated low inoculation levels of Campylobacter more correctly than the high inoculation levels. Counts obtained on the two selective plating media, Abeyta-Hunt-Bark agar added to it 0.1% triphenyl tetrazolium chloride and modified charcoal cephoperazone desoxycholate agar were not significantly different (P=0.143). Expressed as an absolute difference between log(10)-transformed results, the overall values for repeatability (r) and reproducibility (R) were r=log(10) 0.43 and R=log(10) 1.99, respectively. By omitting results from laboratories with high level of variability in results, R was reduced to log(10) 1.88. We suggest that the poor detection of low numbers, the underestimation in milk samples, and the large variation between laboratories can be explained by the general difficulties in handling Campylobacter. In conclusion, NMKL 119, 3. Ed., 2007, is regarded as an acceptable protocol for detection of thermotolerant Campylobacter at concentrations above 25 cfu g(-1) and also for enumeration of thermotolerant Campylobacter in chicken meat.

Survival of Campylobacter jejuni in different gas mixtures.

Campylobacter jejuni in fresh chilled chicken meat is known to be a major risk factor for human gastrointestinal disease. In the present study, the survival under chilled conditions of different C. jejuni strains exposed to different gas mixtures usually used for gas packaging of food was examined. Bolton broth and fresh, skinless chicken fillets were inoculated with six and four strains, respectively, and exposed to the gas mixtures 70/30% O(2)/CO(2), 70/30% N(2)/CO(2), and 100% N(2) (the latter only investigated in broth) at refrigeration temperature (4-5 degrees C). In broth culture, the strains survived significantly longer when exposed to 100% N(2) and 70/30% N(2)/CO(2) than in the oxygen-containing gas mixture, 70/30% O(2)/CO(2) (P<0.0001). For the two anaerobic gas mixtures, the reductions only reached 0.3-0.8 log(10) CFU mL(-1) within the same period. In the presence of oxygen, the numbers of C. jejuni were reduced by a minimum of 4.6 log(10) CFU mL(-1) over 21 days. When inoculated onto chicken fillets, the C. jejuni strains also died significantly faster in the oxygen-containing gas mixture, 70/30% O(2)/CO(2) (P<0.0001), reaching reductions of 2.0-2.6 log(10) CFU g(-1) after 8 days. In the gas mixture without oxygen (70/30% N(2)/CO(2)), no reductions were observed.

A comparative study of two food model systems to test the survival of Campylobacter jejuni at -18 degrees C.

The survival of Campylobacter jejuni NCTC 11168 was tested at freezing conditions (-18 degrees C) over a period of 32 days in two food models that simulated either (i) the chicken skin surface (skin model) or (ii) the chicken juice in and around a broiler carcass (liquid model). In the skin model, cells were suspended in chicken juice or brain heart infusion broth (BHIB) and added to 4-cm2 skin pieces, which were subsequently stored at -18 degrees C. In the liquid model, cells were suspended in chicken juice or BHIB and stored at -18 degrees C. The decrease in the number of viable C. jejuni NCTC 11168 cells was slower when suspended in chicken juice than in BHIB. After freezing for 32 days, the reductions in the cell counts were 1.5 log CFU/ml in chicken juice and 3.5 log CFU/ml in BHIB. After the same time of freezing but when inoculated onto chicken skin, C. jejuni NCTC 11168 was reduced by 2.2 log units when inoculated in chicken juice and 3.2 log units when inoculated into BHIB. For both models, the major decrease occurred within the first 24 h of freezing. The results obtained in the liquid model with chicken juice were comparable to the reductions of Campylobacter observed for commercially processed chickens. The survival at -18 degrees C in the liquid model was also tested for three poultry isolates and three human clinical isolates of the serotypes 1.44, 2, and 4 complex. As observed for C. jejuni NCTC 11168, all the strains survived significantly better in chicken juice than in BHIB and were not notably influenced by serotype or origin. The findings indicate that the composition of the medium around the bacteria, rather than the chicken skin surface, is the major determining factor for the survival of C. jejuni at freezing conditions. The liquid model with chicken juice was therefore the best model system to study the freezing tolerance in Campylobacter strains.

Occurrence of natural Bacillus thuringiensis contaminants and residues of Bacillus thuringiensis-based insecticides on fresh fruits and vegetables.

A total of 128 Bacillus cereus-like strains isolated from fresh fruits and vegetables for sale in retail shops in Denmark were characterized. Of these strains, 39% (50/128) were classified as Bacillus thuringiensis on the basis of their content of cry genes determined by PCR or crystal proteins visualized by microscopy. Random amplified polymorphic DNA analysis and plasmid profiling indicated that 23 of the 50 B. thuringiensis strains were of the same subtype as B. thuringiensis strains used as commercial bioinsecticides. Fourteen isolates were indistinguishable from B. thuringiensis subsp. kurstaki HD1 present in the products Dipel, Biobit, and Foray, and nine isolates grouped with B. thuringiensis subsp. aizawai present in Turex. The commercial strains were primarily isolated from samples of tomatoes, cucumbers, and peppers. A multiplex PCR method was developed to simultaneously detect all three genes in the enterotoxin hemolysin BL (HBL) and the nonhemolytic enterotoxin (NHE), respectively. This revealed that the frequency of these enterotoxin genes was higher among the strains indistinguishable from the commercial strains than among the other B. thuringiensis and B. cereus-like strains isolated from fruits and vegetables. The same was seen for a third enterotoxin, CytK. In conclusion, the present study strongly indicates that residues of B. thuringiensis-based insecticides can be found on fresh fruits and vegetables and that these are potentially enterotoxigenic.

The effect of slaughter operations on the contamination of chicken carcasses with thermotolerant Campylobacter.

To evaluate the effect of specific slaughter operations on the contamination of broiler carcasses with naturally occurring thermotolerant Campylobacter, experiments were carried out in two Danish commercial slaughter plants (Plant I and Plant II). Six broiler flocks determined Campylobacter positive prior to slaughter were investigated at four sampling locations within each slaughter plant. Quantification of thermotolerant Campylobacter in 30 neck skin samples per flock per sampling location showed that the evisceration operation in Plant I led to a significant increase in the Campylobacter concentration of 0.5 log(10) cfu/g in average, whereas no significant changes were observed during this operation in Plant II. Air chilling (Plant I) and water chilling (Plant II), both including a carcass wash prior to the chilling operation, caused similar, but significant reductions of 0.83 and 0.97 log(10) cfu/g, respectively. In packed frozen chickens (Plant II) an additional reduction of 1.38 log(10) cfu/g in average was obtained due to the freezing operation. In packed chilled chickens (Plant I), however, the number of thermotolerant Campylobacter per gram remained at the same level as after air chilling. Enumeration of thermotolerant Campylobacter in 30 intestinal samples per flock showed that in two of the six flocks examined the within flock colonization was very low (<3% and 27% positive samples). The remaining four flocks were colonized at percentages of 100 (three flocks) and 97 (one flock) and had intestinal mean counts ranging from 6.65 to 8.20 log(10) cfu/g. A correlation between Campylobacter concentrations in intestinal content and on chicken carcasses after the defeathering operation was documented. This finding indicates that a reduction in the Campylobacter concentration on chicken carcasses may also be obtained by interventions aimed at reducing the concentration of Campylobacter in the intestines of the living birds.

Antimicrobial resistance among Campylobacter jejuni isolated from raw poultry meat at retail level in Denmark.

Campylobacter jejuni isolated from raw poultry meat collected at retail shops in Denmark in the period 1996-2003 were tested for susceptibility to seven antimicrobial agents. The food samples consisted of raw chicken meat and other raw poultry meat of domestic or imported origin. The highest levels of resistance among C. jejuni were observed for tetracycline, nalidixic acid and ciprofloxacin, whereas macrolide resistance was rarely detected. C. jejuni originating from other poultry meat (mainly duck and turkey meat) exhibited the highest occurrences of antimicrobial resistance monitored; approximately one third of the isolates were tetracycline resistant (N=100). Among chicken meat isolates, the occurrence of tetracycline resistance was significantly higher (P<0.005) in C. jejuni isolated from imported chicken meat (N=88) than in C. jejuni from Danish chicken meat (N=367). The same tendency was observed for chloramphenicol, nalidixic acid and ciprofloxacin (P<0.05). The trends in resistance in the period 1996-2003 among C. jejuni isolates from chicken meat indicate a decrease in the occurrence of resistance towards fluoroquinolones. This may be due to reduced application of fluoroquinolones for food animals. Monitoring of the occurrence of antimicrobial resistance in C. jejuni isolated from raw uncooked poultry has been performed on a yearly basis since 1996, thus providing useful insight into consumer exposure to antimicrobial-resistant C. jejuni.

Occurrence and significance of Bacillus cereus and Bacillus thuringiensis in ready-to-eat food.

Among 48,901 samples of ready-to-eat food products at the Danish retail market, 0.5% had counts of Bacillus cereus-like bacteria above 10(4) cfu g(-1). The high counts were most frequently found in starchy, cooked products, but also in fresh cucumbers and tomatoes. Forty randomly selected strains had at least one gene or component involved in human diarrhoeal disease, while emetic toxin was related to only one B. cereus strain. A new observation was that 31 out of the 40 randomly selected B. cereus-like strains could be classified as Bacillus thuringiensis due to crystal production and/or content of cry genes. Thus, a large proportion of the B. cereus-like organisms present in food may belong to B. thuringiensis.

A model of hygiene practices and consumption patterns in the consumer phase.

A mathematical model is presented, which addresses individual hygiene practices during food preparation and consumption patterns in private homes. Further, the model links food preparers and consumers based on their relationship to household types. For different age and gender groups, the model estimates (i) the probability of ingesting a meal where precautions have not been taken to avoid the transfer of microorganisms from raw food to final meal (a risk meal), exemplified by the event that the cutting board was not washed during food preparation, and (ii) the probability of ingesting a risk meal in a private home, where chicken was the prepared food item (a chicken risk meal). Chicken was included in the model, as chickens are believed to be the major source of human exposure to the foodborne pathogen Campylobacter. Monte Carlo simulations showed that the probability of ingesting a risk meal was highest for young males (aged 18-29 years) and lowest for the elderly above 60 years of age. Children aged 0-4 years had a higher probability of ingesting a risk meal than children aged 5-17 years. This difference between age and gender groups was ascribed to the variations in the hygiene levels of food preparers. By including the probability of ingesting a chicken meal at home, simulations revealed that all age groups, except the group above 60 years of age, had approximately the same probability of ingesting a chicken risk meal, the probability of females being slightly higher than that of males. The simulated results show that the probability of ingesting a chicken risk meal at home does not only depend on the hygiene practices of the persons preparing the food, but also on the consumption patterns of consumers, and the relationship between people preparing and ingesting food. This finding supports the need of including information on consumer behavior and preparation hygiene in the consumer phase of exposure assessments.

Quantitative risk assessment of human campylobacteriosis associated with thermophilic Campylobacter species in chickens.

A quantitative risk assessment comprising the elements hazard identification, hazard characterization, exposure assessment, and risk characterization has been prepared to assess the effect of different mitigation strategies on the number of human cases in Denmark associated with thermophilic Campylobacter spp. in chickens. To estimate the human exposure to Campylobacter from a chicken meal and the number of human cases associated with this exposure, a mathematical risk model was developed. The model details the spread and transfer of Campylobacter in chickens from slaughter to consumption and the relationship between ingested dose and the probability of developing campylobacteriosis. Human exposure was estimated in two successive mathematical modules. Module 1 addresses changes in prevalence and numbers of Campylobacter on chicken carcasses throughout the processing steps of a slaughterhouse. Module 2 covers the transfer of Campylobacter during food handling in private kitchens. The age and sex of consumers were included in this module to introduce variable hygiene levels during food preparation and variable sizes and compositions of meals. Finally, the outcome of the exposure assessment modules was integrated with a Beta-Poisson dose-response model to provide a risk estimate. Simulations designed to predict the effect of different mitigation strategies showed that the incidence of campylobacteriosis associated with consumption of chicken meals could be reduced 30 times by introducing a 2 log reduction of the number of Campylobacter on the chicken carcasses. To obtain a similar reduction of the incidence, the flock prevalence should be reduced approximately 30 times or the kitchen hygiene improved approximately 30 times. Cross-contamination from positive to negative flocks during slaughter had almost no effect on the human Campylobacter incidence, which indicates that implementation of logistic slaughter will only have a minor influence on the risk. Finally, the simulations showed that people in the age of 18-29 years had the highest risk of developing campylobacteriosis.