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Chickens frequently contaminated with Salmonella and Campylobacter

06/2010, 17.03.2010

EU study shows: Pathogens are carried over during slaughter from animals to carcasses

The results of a nationwide study coordinated by BfR show that Campylobacter and Salmonella can frequently be detected at the time of slaughter. The pathogens reach the slaughterhouse in intestinal contents or on the feathers of the animals and can then be carried over during slaughter to the carcasses. From there they reach the food chain and then consumers.  According to the report published today by BfR, Campylobacter were detected on 62 percent and Salmonella on 17.6 percent of the 432 carcasses examined in Germany. In 48.6 percent of the slaughter groups Campylobacter were detected in the intestinal contents of the animals. The study is part of an investigation which was conducted in 2008 in all Member States of the European Union (EU). The results of the EU study were published today by the European Food Safety Authority (EFSA). Campylobacter and Salmonella are the most frequent pathogens of bacterial gastrointestinal diseases in man. "Chicken is the main source of food-borne Campylobacter infections", says BfR President Professor Dr. Dr. Andreas Hensel, "and infections with Salmonella, too, can often be traced back to chicken". Hence, particular attention should be paid to kitchen hygiene when preparing chicken. Poultry meat should only be consumed once it has been heated thoroughly. This inactivates not only Campylobacter and Salmonella but also other potential pathogens. Furthermore, the meat should be stored and prepared separately from other foods to prevent the carry-over of pathogens to other foods.

The contamination of the carcasses with Campylobacter was far lower in the cold winter months than in the summer. Also the amount of Campylobacter on the contaminated carcasses varied considerably from only a few germs to more than 100,000 germs per gram chicken. If Campylobacter were detected in animals from one slaughter batch, then the probability that the carcasses in this batch were also contaminated was particularly high (93 percent positive findings). In the case of carcasses from the slaughter groups that tested negative for Campylobacter in the intestines, the detection rate was 33 percent. Around 80 percent of the Campylobacter detected were Campylobacter jejuni whereas Campylobacter coli accounted for approximately 20 percent. This corresponds to the distribution observed in human infections, too.

Besides Campylobacter, Salmonella were also frequently detected on the carcasses. In this context 14 different Salmonella serovars were detected. The three serovars Salmonella 4,12:d:-, Salmonella typhimurium and Salmonella paratyphi B (dT+) together accounted for more than half (55 percent) of the detections. Already in an earlier study on the incidence of Salmonella in broilers, the frequent detection of the serovars Salmonella 4,12:d:- and Salmonella paratyphi B (dT+) had been observed in this poultry species.

EU-wide 71.2 percent Campylobacter were detected in the intestines of the slaughter groups of broilers and 77 percent on the carcasses. The detection rates in the Member States were between 2 percent and 100 percent for detection in the intestines and between 4.9 percent and 100 percent for detection on the carcasses. The values obtained for Germany were, therefore, lower than the EU average.

EU-wide 15.7 percent of the carcasses were contaminated with Salmonella. The most frequent serovars were Salmonella infantis and Salmonella enteritidis; however the frequent detection of Salmonella infantis reflects the very high level of contamination of animals in one Member State.

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