Norwegian surveillance finds low levels of Salmonella
Norwegian cattle, swine and poultry are only rarely infected with Salmonella, according to the results of surveillance programs in 2020.
Occurrence of Salmonella in Norwegian production animals and animal products is very low compared to most other countries. Salmonellosis has increased in recent decades but the majority of infections are acquired abroad.
Surveillance covers live animals such as pigs, poultry and cattle, eggs and fresh meat from pigs and cattle. Any Salmonella isolated in the programs is notifiable to the Norwegian Food Safety Authority (Mattilsynet). The Norwegian Veterinary Institute coordinates the surveillance programs, examines fecal samples and reports the results. Private laboratories analyze samples collected at slaughterhouses and cutting plants.
Programs are approved by the EU Commission which allows Norway to require additional guarantees on Salmonella when importing live animals and food products of animal origin from the European Union.
The aims of the work include ensuring that Norwegian food-producing animals and products of animal origin are virtually free from Salmonella and to prevent a rise of Salmonella infections in the country.
For poultry, 8,882 fecal samples including boot swabs from 1,342 different holdings were examined. One broiler flock was positive for Salmonella typhimurium.
A total of 1,496 fecal samples from 78 swine breeding herds were examined and Salmonella was not detected. In total, 3,245 lymph node samples from pigs were analyzed. One from slaughter pigs was positive for Salmonella typhimurium.
Almost 3,000 lymph node samples from cattle were examined and three were positive for Salmonella typhimurium, Salmonella Hessarek and Salmonella diarizonae 61:k:1,5,(7). All the herds were followed up by testing feces from different animal species, feed and the environment, and samples were negative.
A total of 5,905 swab samples from cattle and swine carcasses were examined and one was positive for Salmonella diarizonae 61:k:1,5,(7). In total, 2,785 samples of crushed meat from cutting plants were examined and two were positive for Salmonella diarizonae 61:k:1,5,(7) and one for monophasic Salmonella typhimurium.
The number of swab and lymph node samples examined from swine and cattle should be at least 3,000 per year. This target was not reached for all types in 2020 because of the COVID-19 pandemic, but the program still showed a very low Salmonella prevalence, according to the report.
Yersinia in pork findings
Meanwhile, the Norwegian Veterinary Institute has also analyzed pork products for Yersinia enterocolitica.
More than 150 samples of minced, or ground, pork was collected from supermarkets in 2019 and analyzed in 2019 and 2020 after a request from Mattilsynet. Pathogenic Yersinia enterocolitica was isolated from nine samples.
In 2020, there were 82 Yersinia enterocolitica infections reported. There have been between 50 and 100 cases a year since 2010, except for in 2014 when there was an outbreak with 133 cases. Pigs are thought to be the main reservoir for Yersinia enterocolitica, and pork is considered to be a major source of infection.
A total of 26 samples were positive for the ail gene with pathogenic Yersinia enterocolitica in nine of these. Eight out of nine samples were serotype O:3.
Results show there is a low incidence of pathogenic Yersinia enterocolitica in Norwegian pork products. Experts cautioned about the low number of samples analyzed but said findings could help industry and authorities with an overview of the situation and to monitor trends as it provides updated data from the last study in 1997 and 1998.
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