New insight into social relationships in dairy cows and how time of birth, parity, and relatedness affect spatial interactions later in life.

Social interactions between cows play a fundamental role in the daily activities of dairy cattle. Real-time location systems provide on a continuous and automated basis information about the position of individual cows inside barns, offering a valuable opportunity to monitor dyadic social contacts. Understanding dyadic social interactions could be applied to enhance the stability of the social structure promoting animal welfare and to model disease transmission in dairy cattle. This study aimed to identify the effect of different cow characteristics on the likelihood of the formation and persistence of social contacts in dairy cattle. The individual position of the lactating cows was automatically collected once per second for 2 wk, using an ultra-wideband system on a Swedish commercial farm consisting of almost 200 dairy cows inside a freestall barn. Social networks were constructed using the position data of 149 cows with available information on all characteristics during the study period. Social contacts were considered as a binary variable indicating whether a cow pair was within 2.5 m of each other for at least 10 min per day. The role of cow characteristics in social networks was studied by applying separable temporal exponential random graph models. Our results revealed that cows of the same parity interacted more consistently, as well as those born within 7 d of each other or closely related by pedigree. The repeatability of the topological parameters indicated a consistent short-term stability of the individual animal roles within the social network structure. Additional research is required to elucidate the underlying mechanisms governing the long-term evolution of social contacts among dairy cattle and to investigate the relationship between these networks and the transmission of diseases in the dairy cattle population.

Cow characteristics associated with the variation in number of contacts between dairy cows.

In modern freestall barns where large groups of cows are housed together, the behavior displayed by herd mates can influence the welfare and production of other individuals. Therefore, understanding social interactions in groups of dairy cows is important to enhance herd management and optimize the outcomes of both animal health and welfare in the future. Many factors can affect the number of social contacts in a group. This study aimed to identify which characteristics of a cow are associated with the number of contacts it has with other group members in 2 different functional areas (feeding and resting area) to increase our understanding of the social behavior of dairy cows. Inside 2 herds housed in freestall barns with around 200 lactating cows each, cow positions were recorded with an ultra-wideband real-time location system collecting all cows' positions every second over 2 wk. Using the positioning data of the cows, we quantified the number of contacts between them, assuming that cows spending time in proximity to one another (within a distance of 2.5 m for at least 10 min per day) were interacting socially. We documented in which barn areas these interactions occurred and used linear mixed models to investigate if lactation stage, parity, breed, pregnancy status, estrus, udder health, and claw health affect the number of contacts. We found variation in the number of contacts a cow had between individuals in both functional areas. Cows in later lactation had more contacts in the feeding area than cows in early lactation. Furthermore, in one herd, higher parity cows had fewer contacts in the feeding area than first parity cows, and in the other herd, cows in third parity or higher had more contacts in the resting area. This study indicates that cow characteristics such as parity and days in milk are associated with the number of contacts a cow has daily to its herd mates and provides useful information for further research on social interactions of dairy cows.

Cleaning and disinfection of transport crates for poultry - comparison of four treatments at slaughter plant.

Transport crates for poultry can contribute to the spread of pathogens, with those of public health interest, for example, Campylobacter, being of particular importance. A strict cleaning procedure and use of an effective disinfection method for transport equipment are thus important to avoid introduction of Campylobacter to chicken and poultry farms, particularly during flock thinning. This study evaluated the efficacy of the disinfection procedure currently in use at one of the largest slaughter plants in Sweden and compared the effects with those of other disinfection methods. The evaluation was based on treatment ability to reduce the presence and amount of indicator bacteria belonging to the family Enterobacteriaceae and total aerobic bacteria. In 4 trials, sodium hypochlorite, peracetic acid, and drying with hot air, with or without sodium hypochlorite for final disinfection, were compared. The analysis was based on 40 cotton swab samples taken in each treatment, 20 after the soaking stage and 20 after the final disinfection step. The results showed that use of a chemical disinfectant in combination with drying with hot air (dehumidifier) was the most effective treatment, with an average reduction of 3.4 log for total aerobic bacteria and 3.8 log for Enterobacteriaceae. Since all crates treated with hot air were dry, transport conditions for the birds also improved, particularly in cold weather. A disadvantage is that this treatment is energy-consuming and would require substantial technical changes to the current cleaning process, increasing operating costs at the slaughter plant. However, considering the contribution of improved crate cleaning to overall hygiene control within the poultry supply chain and the beneficial effect on animal welfare, the costs may be justified.

The presence of antibiotic-resistant Staphylococcus spp. and Escherichia coli in smallholder pig farms in Uganda.

BACKGROUND: The development of antimicrobial resistance is of global concern, and is commonly monitored by the analysis of certain bacteria. The aim of the present study was to study the antibiotic susceptibility in isolates of Staphylococcus spp. and Escherichia (E.) coli obtained from healthy pigs originating from nineteen herds enrolled in a study on herd health management in Lira district, northern Uganda. Skin and nasal swabs were analyzed for the presence of Staphylococcus spp., and selectively cultivated to investigate the presence of methicillin-resistant Staphylococcus (S.) aureus (MRSA), and rectal swabs were analyzed for the presence of E. coli. Antibiotic susceptibility was tested by broth micro-dilution. Information on the antibiotic usage and treatment regimens during the previous year was gathered using structured interviews and longitudinal data. RESULTS: In Staphylococcus spp., resistance to penicillin (10/19 isolates; 53%), fusidic acid (42%) and tetracycline (37%) were most commonly found. In E. coli, resistance to sulfamethoxazole (46/52 isolates; 88%), tetracycline (54%) and trimethoprim (17%) was most frequent. Methicillin-resistant S. aureus was found in one sample (1/50; 2%). Multi-drug resistant isolates of Staphylococcus spp. and E. coli were found in 54 and 47% of the herds, respectively. At the herd level, no associations could be made between antibiotic resistance and herd size or treatment regimens for either of the bacteria. CONCLUSION: In conclusion, resistance to important antibiotics frequently used in animals in Uganda was common, and the presence of MRSA was demonstrated, in Ugandan pig herds.

Occurrence of Campylobacter spp. in Swedish calves, common sequence types and antibiotic resistance patterns.

AIMS: Cattle are the second most important cause of human campylobacteriosis, after poultry, but there are knowledge gaps regarding Campylobacter in cattle. This study examined the occurrence of Campylobacter, the species present, sequence types and antibiotic resistance in Swedish cattle. METHODS AND RESULTS: Faeces samples collected from 154 calves on seven Swedish farms, and 69 follow-up samples from a second collection occasion, were analysed. Campylobacter were isolated from 77% of calves at the first sampling, with Campylobacter jejuni as the most frequently isolated species. Animals kept on deep straw bedding were less likely to be colonized with Campylobacter. Whole-genome sequencing of 90 C. jejuni samples resulted in 11 sequence types, among which ST-19 and ST-21 were most frequent. Antimicrobial resistance analyses showed that 46% of 142 isolates analysed were resistant to quinolones, while all isolates belonging to ST-19, ST-22 and ST-441 were resistant to ciprofloxacin and nalidixic acid. CONCLUSIONS: Campylobacter jejuni was the species most frequently isolated in calves and a strong association was found between sequence type and antimicrobial resistance pattern. SIGNIFICANCE AND IMPACT OF THE STUDY: The high proportion of calves with quinolone-resistant Campylobacter jejuni should be considered in a One Health perspective.

Detection of Campylobacter spp. in water by dead-end ultrafiltration and application at farm level.

AIMS: The purposes were to evaluate the detection of low levels of Campylobacter in water by dead-end ultrafiltration (DEUF) to determine the sensitivity and suitability for use under field condition. METHODS AND RESULTS: The DEUF technique followed by detection according to ISO 10272 was tested on artificially and naturally contaminated water. Campylobacter were detected in all samples spiked with more than 10 CFU 60 l-1 and in four of nine samples with a concentration below 10 CFU 60 l-1 water. Naturally contaminated water from five different broiler producers was analysed. Campylobacter were detected in four of 12 samples from ponds near the houses and in three of 24 samples from water pipes inside the broiler houses, but not in tap water sampled at the entrance of the broiler houses. CONCLUSIONS: The results indicate that DEUF is useful for detection of low numbers of Campylobacter in large volumes of water. SIGNIFICANCE AND IMPACT OF THE STUDY: Contaminated water is an important source for transmission of Campylobacter to broilers and humans. The concentration of Campylobacter is usually low with a high level of background microbiota. This study shows the advantages of DEUF both in the laboratory and under field conditions.

Knowledge gaps in control of Campylobacter for prevention of campylobacteriosis.

Campylobacteriosis is an important, worldwide public health problem with numerous socio-economic impacts. Since 2015, approximately 230,000 cases have been reported annually in Europe. In the United States, Australia and New Zealand, campylobacteriosis is the most commonly reported disease. Poultry and poultry products are considered important sources of human infections. Poultry meat can become contaminated with Campylobacter during slaughter if live chickens are intestinal carriers. Campylobacter spp. can be transferred from animals to humans through consumption and handling of contaminated food products, with fresh chicken meat being the most commonly implicated food type. Regarding food-borne disease, the most important Campylobacter species are Campylobacter jejuni and Campylobacter coli. In humans, clinical signs of campylobacteriosis include diarrhoea, abdominal pain, fever, headache, nausea and vomiting. Most cases of campylobacteriosis are sporadic and self-limiting, but there are post-infection complications, for example, Guillain-Barrés syndrome. This review summarizes an analysis undertaken by the DISCONTOOLS group of experts on campylobacteriosis. Gaps were identified in: (i) knowledge of true number of infected humans; (ii) mechanisms of pathogenicity to induce infection in humans; (iii) training to prevent transfer of Campylobacter from raw to ready-to-eat food; (iv) development of effective vaccines; (v) understanding transmission routes to broiler flocks; (vi) knowledge of bacteriocins, bacteriophages and antimicrobial peptides as preventive therapies; (vii) ration formulation as an effective preventive measure at a farm level; (viii) development of kits for rapid detection and quantification of Campylobacter in animals and food products; and (ix) development of more effective antimicrobials for treatment of humans infected with Campylobacter. Some of these gaps are relevant worldwide, whereas others are more related to problems encountered with Campylobacter in industrialized countries.

Confirmation of a Campylobacteriosis Outbreak Associated with Chicken Liver Pâté Using PFGE and WGS.

In May 2012, an outbreak of campylobacteriosis occurred in southern Sweden at a wedding reception affecting 44 persons. A total of 17 cases were notified (13 were culture positive for Campylobacter spp.). Epidemiological investigation suspected chicken liver pâté as the source of infection. The liver pâté had been deliberately undercooked, lightly fried to keep the right texture and mixed with spices. Campylobacter isolates from six cases as well as three Campylobacter isolates from chicken flocks previously raised by the producer delivering the liver were subtyped using pulsed-field gel electrophoresis and whole-genome sequencing. Indistinguishable PFGE profiles were identified among five human and one chicken C. jejuni isolates as well among the two C. coli isolates, one from a human case and one from a chicken. WGS supported the PFGE findings; the six C. jejuni isolates belonged to one cluster. All these six isolates were of MLST type ST 50 (ST-CC 21). This study highlights the importance of a combination of strict biosecurity at the flock-level as well as adequate cooking of chicken liver to prevent transmission of Campylobacter to humans.

Associations between Campylobacter levels on chicken skin, underlying muscle, caecum and packaged fillets.

A study was performed with the aim to investigate associations between Campylobacter in chicken caecum, carcass skin, underlying breast muscle and packaged breast fillets. Samples were taken from 285 chickens from 57 flocks and analysed according to ISO 10272. Campylobacter spp. were isolated from caecal samples from 41 flocks. From birds of the same 41 flocks Campylobacter could be detected and quantified in 194 (68%) skin samples. Moreover, Campylobacter spp. were enumerated in 13 (5%) underlying muscle samples originating from 9 of the 41 flocks. The mean number of Campylobacter spp. in the 194 skin samples which could be counted was 2.3 log cfu/g and for the 13 underlying muscle samples 1.3 log cfu/g. Campylobacter could only be quantified in those breast muscle samples with a finding in corresponding skin sample. Five packaged chicken fillets were taken from each 25 of the 57 flocks and analysed both quantitatively and qualitatively. In qualitative analysis Campylobacter was detected in 79 (63%) fillets from 16 flocks and quantified in 24 (19%) samples from 11 flocks. The results showed a significant association (P < 0.05) between findings of Campylobacter on carcass skin (log cfu/g) and the proportion of Campylobacter positive breast muscle samples.

The clinical significance of Nicoletella semolina in horses with respiratory disorders and a screening of the bacterial flora in the airways of horses.

Nicoletella semolina, a member of the family Pasteurellaceae, can be isolated from the airways of horses with respiratory disorders. However, its role as a potential or opportunistic pathogen is not clear nor is its presence as part of the normal flora. We therefore investigated the presence and bacterial load of N. semolina in healthy and diseased horses. Samples from a healthy control group were compared with samples from the routine analysis of horses with a clinical history of respiratory disorders. A total of 1770 nose swabs and 1132 tracheal aspirate samples were analysed and subjected to conventional bacteriological examination. N. semolina was isolated from 12 (6%) of 207 nose samples from the healthy control group and from 42 (3%) of 1563 samples from horses with respiratory disorders. In tracheal aspirate, N. semolina was isolated from 7 (3%) of 211 samples from the control group and 49 (5%) of 921 samples from horses with respiratory disorders. Other bacteria were also isolated in laboratory analyses, the most commonly isolated bacterium in both the control group and the respiratory disorders group being Streptococcus equi subsp. zooepidemicus. It was isolated in 21% of tracheal aspirate from the control group and 33% of those from horses with respiratory disorders. In conclusion, N. semolina is not a primary pathogenic bacterium, as it was isolated at similar frequencies in horses with respiratory disorders and those in the healthy control group.

Occurrence of pathogens in wild rodents caught on Swedish pig and chicken farms.

A total of 207 wild rodents were caught on nine pig farms, five chicken farms and five non-farm locations in Sweden and surveyed for a selection of bacteria, parasites and viruses. Lawsonia intracellularia and pathogenic Yersinia enterocolitica were only detected in rodents on pig farms (9% and 8% prevalence, respectively) which indicate that these agents are more likely to be transmitted to rodents from pigs or the environment on infected farms. Brachyspira hyodysenteriae (1%), Brachyspira intermedia (2%), Campylobacter jejuni (4%), Campylobacter upsaliensis (2%), leptospires (7%) and encephalomyocarditis virus (9%) were also detected from rodents not in contact with farm animals. Giardia and Cryptosporidium spp. were common, although no zoonotic types were verified, and Salmonella enterica was isolated from 1/11 mice on one farm but not detected by PCR from any of the rodents. Trichinella spp. and Toxoplasma gondii were not detected.

Biosecurity-based interventions and strategies to reduce Campylobacter spp. on poultry farms.

The prevention and control of Campylobacter colonization of poultry flocks are important public health strategies for the control of human campylobacteriosis. A critical review of the literature on interventions to control Campylobacter in poultry on farms was undertaken using a systematic approach. Although the focus of the review was on aspects appropriate to the United Kingdom poultry industry, the research reviewed was gathered from worldwide literature. Multiple electronic databases were employed to search the literature, in any language, from 1980 to September 2008. A primary set of 4,316 references was identified and scanned, using specific agreed-upon criteria, to select relevant references related to biosecurity-based interventions. The final library comprised 173 references. Identification of the sources of Campylobacter in poultry flocks was required to inform the development of targeted interventions to disrupt transmission routes. The approach used generally involved risk factor-based surveys related to culture-positive or -negative flocks, usually combined with a structured questionnaire. In addition, some studies, either in combination or independently, undertook intervention trials. Many of these studies were compromised by poor design, sampling, and statistical analysis. The evidence for each potential source and route of transmission on the poultry farm was reviewed critically, and the options for intervention were considered. The review concluded that, in most instances, biosecurity on conventional broiler farms can be enhanced and this should contribute to the reduction of flock colonization. However, complementary, non-biosecurity-based approaches will also be required in the future to maximize the reduction of Campylobacter-positive flocks at the farm level.

Risk factors associated with the presence of Campylobacter-positive broiler flocks in Sweden.

Approximately 40% of Swedish broiler producers deliver Campylobacter-negative broilers in 90-100% of their flocks, showing that it is possible to produce Campylobacter-free broilers in Sweden. This study investigated risk factors associated with the presence of Campylobacter-positive flocks at Swedish broiler producers. A total of 37 producers, with 90 broiler houses including 144 compartments, participated in the study. An on-farm interview was performed to collect information on potential risk factors for Campylobacter infection in broilers, with questions about farmcharacteristics such as the environment around the farm and broiler houses, design of the broiler houses and on-farm management practices. Negative binomial regression models were used to assess the statistical significance of risk factors associated with the within-farm number of Campylobacter-positive flocks (the outcome). Campylobacter is transmitted in broiler flocks due to multiple factors and several potential sources, illustrating the complexity of Campylobacter epidemiology in broilers. Factors significantly associated with increased proportion of Campylobacter-positive flocks were the presence of other livestock on the farm, or the presence of cattle, swine, poultry or fur animals within 1km of the farm. Poor or average general tidiness were associated with increased proportion of Campylobacter-positive flocks, but decreased if split slaughter was seldom or never applied or if farm workers changed footwear twice or three times instead of once before entering the broiler house.

Trends in Campylobacter incidence in broilers and humans in six European countries, 1997-2007.

The objective of this study was to examine incidences of Campylobacter in broilers and humans, and to describe seasonal variation and long-term trends by comparing longitudinal surveillance data in six Northern European countries (Denmark, Finland, Iceland, Norway, Sweden and the Netherlands). Due to high degree of seasonality and autocorrelation, seasonally adjusted (de-seasonalized) and trend adjusted data (de-trended) were used for comparing incidences within and between the six countries. De-seasonalized time series were obtained by fitting the incidence time series to mean monthly temperature and then removing this effect from the data. Long-term trends were fitted to the de-seasonalized time series. The incidence of Campylobacter colonization in broiler flocks and incidence of campylobacteriosis in humans showed a concordant seasonality for all the countries. There was a strong association between the incidence in both broilers and humans in a given month and the mean temperature of the northern hemisphere in the same month, as well as the preceding month, as shown by the cross-correlations and the chosen Generalized Additive Model. Denmark and Sweden showed a steadily decreasing trend for Campylobacter in broilers and human campylobacteriosis in the period 2001-2007. In Iceland, there was a decreasing trend for campylobacteriosis in humans from 1999 to 2007, whilst the broiler trend for Campylobacter was stable from 2001 to 2004, then falling thereafter. In Norway, the human campylobacteriosis trend showed a steady increase throughout the period. On the other hand, the Norwegian broiler trend for Campylobacter showed a decrease from 2001 until 2004, but was thereafter stable. There was no significant decrease or increase in incidence for human campylobacteriosis in the Netherlands, and the trend for Campylobacter in broilers was close to stable. The seasonality seen in broiler and human closely follows the temperature, and was probably caused, at least partly, by temperature related factors.

Expression of X-chromosome linked inhibitor of apoptosis protein in mature Purkinje cells and in retinal bipolar cells in transgenic mice induces neurodegeneration.

Transgenic mice with overexpression of the caspase-inhibitor, X-chromosome-linked inhibitor of apoptosis protein (XIAP) in Purkinje cell (PC) and in retinal bipolar cells (RBCs) were produced to study the regulation of cell death. Unexpectedly, an increased neurodegeneration was observed in the PCs in these L7-XIAP mice after the third postnatal week with the mice exhibiting severe ataxia. The loss of PCs was independent of Bax as shown by crossing the L7-XIAP mice with Bax gene-deleted mice. Electron microscopy revealed intact organelles in PCs but with the stacking of ER cisterns indicative of cell stress. Immunostaining for cell death proteins showed an increased phosphorylation of c-Jun in the PCs, suggesting an involvement in cell degeneration. Apart from PCs, the number of RBCs was decreased in adult retina in line with the expression pattern for the L7 promoter. The data show that overexpression of the anti-apoptotic protein XIAP in vulnerable neurons leads to enhanced cell death. The mechanisms underlying this neurodegeneration can be related to the effects of XIAP on cell stress and altered cell signaling.

Summary of the Swedish Campylobacter program in broilers, 2001 through 2005.

A Campylobacter monitoring program in broiler chickens was carried out in Sweden from 2001 through 2005. The objective was to reduce the occurrence of Campylobacter in the food chain through preventive measures, starting with primary production. The program involved collecting samples from all broiler flocks at slaughter and occasional additional times. The annual incidence of Campylobacter-positive slaughter batches progressively decreased from 20% in 2002 to 13% in 2005. Most of the positive batches had a high within-flock prevalence of Campylobacter. However, about 18% of the positive batches had a low-within-flock prevalence; Campylobacter spp. were isolated from at most 50% of the cloacal samples. The incidence of batches contaminated at slaughter ranged between 6 and 9% during the study period. During all 5 years, a seasonal peak of incidence was observed in the summertime. In an additional study, quantitative analyses were performed on neck skin samples and carcass rinse samples. Those results were compared with the positive and negative findings of the cloacal, cecum, and neck skin samples at slaughter. When Campylobacter was found in the cecum, there was a higher level of Campylobacter in the quantitative analyses. Those batches where Campylobacter already had been found on the farm had a higher concentration of Campylobacter than those batches in which Campylobacter was found only at slaughter. During the study period, about one-third of producers seldom delivered Campylobacter-positive batches (< 10% positive batches per year). Thus, it is possible to produce Campylobacter-free broilers in Sweden.

Correlations between Campylobacter spp. prevalence in the environment and broiler flocks.

AIMS: To investigate (i) possible correlations between the presence of Campylobacter spp. in the surroundings of broiler farms and their incidence in flocks, and (ii) possible associations between weather conditions and the occurrence of Campylobacter spp. METHODS AND RESULTS: Farms were selected according to previous results from the Swedish Campylobacter programme. Samples were collected in and around broiler houses during the rearing period from 131 flocks on 31 farms, including sock samples from the ground outside, from the floor in the broiler houses and anterooms, and samples from insects, water, feed and ventilation shafts. CONCLUSIONS: As expected, there was a difference in Campylobacter isolation rates for different categories of farms regarding samples taken in the houses. However, there were no differences regarding the presence of Campylobacter spp. in the environment between producers that often deliver Campylobacter-positive slaughter batches and those that rarely deliver positive batches. Campylobacter spp. were more frequently found in the surroundings on rainy days when compared with sunny days. SIGNIFICANCE AND IMPACT OF THE STUDY: Physical barriers between outside and inside the houses appeared to be important for preventing Campylobacter spp. in the environment to be transferred into the broiler houses.

Postchill campylobacter prevalence on broiler carcasses in relation to slaughter group colonization level and chilling system.

Data from an ongoing national surveillance program of Campylobacter prevalence in broiler slaughter groups were related to results from a 1-year baseline study of broiler carcasses postchill. The goals were to establish the relation between Campylobacter prevalence in slaughter groups and on carcasses and to determine the effect of various chilling systems on Campylobacter prevalence. Pooled cloacal and neck skin samples from the surveillance program were analyzed after enrichment. Carcass rinse samples from the baseline study were analyzed after enrichment and by direct plating. Data from both studies were available for 614 carcasses. Direct-plating analyses indicated that the percentages of carcasses positive for Campylobacter jejuni and other Campylobacter spp. in slaughter groups with negative cloacal samples were 2 and 10%, respectively, whereas enrichment analyses indicated prevalences of 2% in both cases. Campylobacter prevalence in slaughter groups with a high degree of intestinal colonization (more than half of the pooled cloacal samples positive) was significantly higher than in slaughter groups with a low degree of colonization (76 to 85% and 30 to 50%, respectively, depending on Campylobacter spp. and analytical method). The prevalence of Campylobacter-positive carcasses postchill was at the same level as the prevalence of carcasses that originated from slaughter groups with positive neck skin samples at four of the six slaughterhouses. Only at one slaughterhouse, with an air-chilling system, was the postchill prevalence (13%) lower than that expected from slaughter group data (23%). The postchill prevalence (43%) was higher than that expected from slaughter group data (33%) at one slaughterhouse with immersion chilling.

The estimated accuracy of the EU reference dissection method for pig carcass classification.

This experiment was designed to describe the accuracy of the EU-reference dissection method, and to describe the types of factors influencing the accuracy and assess their size. The experiment was conducted in four different European countries at two abattoirs within each country. A total of 128 carcasses was selected according to carcass weight, fat class and sex, and 8 butchers from different countries dissected the carcasses. Due to the experimental design of the experiment a variation in pig type was found between countries. The accuracy was expressed by the repeatability and reproducibility standard deviation, which were found to be 0.87 and 1.10, respectively, and by the reliability, found to be 0.87. This indicates a high accuracy, although a significant effect was found on the estimation of lean meat percentage (LMP) of butcher, and also that jointing of the carcass was of overall importance to the accuracy of the EU-reference dissection method.

Transmission of Campylobacter spp. to chickens during transport to slaughter.

AIMS: To determine the prevalence of Campylobacter-contaminated transport crates and to determine whether contaminated crates represent a risk for contamination of chickens during transport to slaughter. METHODS AND RESULTS: Samples were collected from cleaned transport crates before they were dispatched to the farms. Chicken groups were sampled within 24 h before transport to slaughter and at the slaughterhouse. Campylobacter spp. were isolated from 69 of 122 (57%) sampled batches of transport crates. Twenty-six slaughter groups, negative at farm level, were transported in batches of crates from which Campylobacter spp. had been isolated. In 11 (42%) of these 26 slaughter groups, Campylobacter spp. were found in samples taken at slaughter. The corresponding figure for at-farm-negative slaughter groups transported in negative crates was four (15%) testing positive at slaughterhouse of 27 slaughter groups [relative risk (RR) = 2.9, 95% CI 1.1-7.3]. In four of 11 slaughter groups, genetic subtyping by pulsed-field gel electrophoresis was able to support the hypothesis of contamination from crates to chickens during transport to slaughter. CONCLUSIONS: Despite washing and disinfection, crates were frequently contaminated with Campylobacter and it could have contaminated chickens during transport to slaughter. SIGNIFICANCE AND IMPACT OF THE STUDY: Campylobacter-positive crates are a risk factor for chickens testing campylobacter-positive at slaughter.