Authorities in Sweden are investigating an increase in Campylobacter infections linked to fresh chicken.

The number of domestic cases of Campylobacter infection was higher in November than expected for the season. This increase coincides with reports of an unusually high incidence of Campylobacter in chicken flocks and cases linked to working with chickens. Folkhälsomyndigheten (Public Health Agency of Sweden) officials said it is not yet known if there is a link between these different events.

The news comes just more than one year after an outbreak was declared over with an estimated 5,000 more Campylobacter cases reported in the country between August 2016 and May 2017 than normal levels.

A spokeswoman for the agency told Food Safety News that Campylobacter in Sweden follows a seasonal variation with the highest number of cases during the summer months and a drop when fall comes.

“In November there was a deviation in that trend and the number of cases started to increase again. During the first three weeks in November last year we had an average of domestic cases, including cases with unknown country of infection, just below 70 cases per week. During the same period this year the average number of cases is over 90,” she said.

“It was also brought to our attention that the number of positive broiler flocks had increased. This data is collected within the Campylobacter surveillance program for chicken. In addition, a cluster of six cases was also reported to us from a regional county medical office in the southern part of the country. The cases were all workers employed at a chicken slaughterhouse.”

The suspicion that fresh chicken is causing the increase in human cases is based on the coinciding problems in chicken production.

“It has come to Folkhälsomyndigheten’s attention that there have been problems with sick birds at the breeders, which leads to more personnel having to go in and out of the chicken houses, attending to sick/dead birds, i.e. biosafety barriers can then more easily be broken which in turn could put the chickens at a higher risk of being infected by Campylobacter,” said the spokeswoman.

Livsmedelsverket (National Food Agency) officials said no sampling of fresh chickens to help find the source is planned and investigations on causes of the Campylobacter increase in chicken flocks are ongoing.

The advice from the agencies for consumers is to ensure optimum kitchen hygiene when handling raw chicken meat and to cook the meat thoroughly.

Officials from both agencies said there was no link to the previous outbreak in 2016 and 2017 linked to chilled chicken produced by Kronfågel. This was initially explained by warmer weather than usual. However, in January 2017 a fault was found as part of the installation of an area to wash the boxes that transport chickens from farms to the slaughterhouse and it was corrected.

Kronfågel is one of the largest companies in the poultry indus­try in Sweden with a market leading position.

The outbreak was subject to an external investigation to help draw conclusions and take measures to reduce the risk of future similar events. This was done by the National Institute for Health and Welfare (THL) in Finland and the Finnish Food Safety Authority (Evira).

The Folkhälsomyndigheten spokeswoman said it has informed the public of the problem at a much early phase this time and has initiated start-up of the zoonotic crises management team to get all the agencies coordinated.

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