29.07.2013

Campylobacteriosis remains the most common cause of bacterial foodborne gastrointestinal illness in Denmark and broilers have been identified as the primary source, though other sources also exist. Therefore, reducing the occurrence of Campylobacter in the broiler production is considered important for reducing the number of human cases. Risk factor studies have been carried out to identify the factors that significantly affect the risk of broilers becoming colonised with Campylobacter.
From 1999 to 2011, the Danish broiler industry has undergone some important changes. During this time, the number of broiler farms has decreased. Furthermore, in 2003 a strategy against Campylobacter was adopted, following which the Campylobacter flock prevalence in broiler flocks decreased. In 2008 an action plan was introduced, and testing of all flocks became mandatory from 2010 (Order no 1462 of 16/12/2009). A key element of this plan was to develop and implement a quality assurance programme for broiler farmers, in order to increase the focus on biosecurity measures on broiler farms. Biosecurity measures include having anterooms divided in separate zones and/or hygiene barriers at the house entrance; changing clothes and footwear and washing hands before entering the broiler house; using clean drinking water; rodent control and having vegetation free zones around the house. Today, conventional broiler farms that produce broilers for the two main broiler companies in Denmark (98% of the Danish broiler production) comply with a quality scheme laid down by the broiler companies. Studies found that the age of the broiler house as a significant risk factor. Thus, flocks raised in older houses were more often found to be colonised with Campylobacter.

This may be explained by the fact that it is more difficult to implement and uphold modern biosecurity standards in older houses.
A number of factors related to the biosecurity on the farms were found to be significantly associated with occurrence of Campylobacter:
- insufficient rodent control
- a high number of chimneys on the houses and
- improper storage of whole wheat used as feed (i.e. not stored in a silo)
- lack of a separate anteroom,
- presence of boot dips
- the length of downtime between flocks (the number of days from a house is emptied until it is restocked) and
- type of drinkers used (nipples with or without cups or bells). It was interesting that boot dips were associated with a higher Campylobacter prevalence. A long downtime was found to be associated with a higher prevalence of Campylobacter among the broiler flocks. 

It was also found that decreasing density of birds and number of houses on the farm to be a risk factor.
Age at slaughter was also found to be associated with a higher risk, and may simply reflect that the longer the broilers live, the more likely they are to be exposed to
Campylobacter from the environment.