A study on Campylobacter in Norwegian broiler flocks older than 50 days at slaughter has indicated age and outdoor access are important risk factors.

The research work in 2018 shows that 43.3 percent of flocks tested positive for Campylobacter jejuni when sampled at slaughter. Broilers more than 50 days of age at slaughter were last included in a surveillance program in 2006.

Campylobacter jejuni was the only species detected. Birds from a slaughterhouse with the oldest flocks had the highest prevalence of Campylobacter at 87.5 percent, or 21 of 24 flocks positive. They also had outdoor access.

Those from a slaughterhouse with the youngest flocks did not have outdoor access and had the lowest prevalence at 22.2 percent, or four of 18 flocks positive for Campylobacter.

Norway’s action plan
Campylobacteriosis is the most common bacterial infectious disease in Norway. In almost half of cases, infection is acquired in the country. Consumption of poultry meat bought raw is a significant risk factor, together with drinking un-disinfected water, eating at barbecues, occupational exposure to animals, and eating undercooked pork.

An action plan on Campylobacter spp. in Norwegian broilers slaughtered up to 50 days of age started in spring 2001. It includes pre-slaughter surveillance of the flocks and freezing or heat-treating of carcasses/meat from flocks positive for Campylobacter.

The plan does not include surveillance of broilers older than 50 days of age at slaughter. These older broilers cover different farming systems from conventional indoor-raised to organic farming. Some systems are free-range, other flocks are more or less sheltered from the outdoor environment.

Broiler flocks more than 50 days old at the time of slaughter were sampled by the Norwegian Food Safety Authority (Mattilsynet) at three slaughterhouses in the southern and eastern part of the country from May to October last year.

This helps assess if meat products from broiler flocks not included in the surveillance programme are a food safety risk to consumers.

Age and outdoor access
A total of 104 flocks were sampled, estimated to be 50 percent of the flocks older than 50 days of age slaughtered in Norway in the sampling period, and 45 were positive for Campylobacter jejuni.

Monthly distribution of positive flocks did not show the same distribution as for flocks in the action plan. Prevalence of Campylobacter spp. in broilers slaughtered up to 50 days of age in the action plan has shown a peak in July and August while the study had high levels in July, August, September and October.

Age of the sampled flocks ranged between 52 and 92 days at slaughter. Campylobacter results related to age indicated older chickens had the highest prevalence with only 14 percent positive at 52 to 58 days at slaughter compared to 75 percent when flocks were older than 69 days.

The first slaughterhouse had the highest incidence of Campylobacter positive flocks. These flocks were the oldest and all had reported outdoor access. Flocks from the third slaughterhouse had the lowest mean age, and none of them had outdoor access. The second slaughterhouse had a mixture of flocks with and without outdoor access.

Prevalence in the study was higher than that among flocks in the action plan which was 6.3 percent in the same period. However, this finding was not unexpected as the study looked at older broilers and several flocks with outdoor access which are known risk factors.

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