Risk Assessment and Nutrition, The National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark.
Risk Assessment and Nutrition, The National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark; Data Analysis and Statistics, DTU Compute, Technical University of Denmark, Building 324, DK-2800 Kgs. Lyngby, Denmark.
Prev Vet Med. 2016 Aug 1;130:137-45. doi: 10.1016/j.prevetmed.2016.04.002. Epub 2016 Apr 5.
Campylobacteriosis has become the leading bacterial zoonosis in humans in the European Union and other developed countries. There are many sources of human Campylobacter infections, but broilers and broiler meat have been shown to be the most important. In order to implement effective interventions that reduce the probability of Campylobacter colonisation of broiler flocks, it is essential to fully understand the risk factors involved. We present a bi-national risk factor survey comprising Campylobacter data from more than 5200 Danish and Norwegian indoor, conventional broiler flocks and the responses to a standardised questionnaire, with more than 40 explanatory variables from 277 Danish and Norwegian farms. We explored several models by using different combinations of the Danish and Norwegian data, including models with single-country datasets. All models were analysed using a generalized linear model using backwards elimination and forward selection. The results show that Norwegian broiler flocks had a lower risk of being colonised than Danish flocks. Farm specific variables that increased the risk of flocks becoming colonised with Campylobacter in both countries were: broiler houses older than five years; longer downtime (no. of days between flocks), probably a consequence of longer downtimes being associated with less focus on maintaining a high biosecurity level; broiler houses without a separate ante-room or barrier; and the use of the drinker nipples with cups or bells compared with nipples without cups. Additional country specific risk factors were also identified. For Norway, the risk of colonisation increased with increasing numbers of houses on a farm and when the water used for the broilers originated from surface water or bore holes instead of mains. For Denmark, having boot dips or low stocking density increased the risk of a flock becoming Campylobacter positive. The different model approaches allowed us to explore the effect of having a large number of data available to identify the significant variables. To a large extent, the country specific models identified risk factors that were also found in the bi-national model. However, the bi-national model identified more risk factors than the country specific models. This indicated that combining the data sets from the two countries did not disrupt the results but was beneficial due to the greater strength achieved in the statistical analyses and the possibility of examining interactions terms with the variable Country.
空肠弯曲菌病已成为欧盟和其他发达国家人类中主要的细菌性人畜共患病。人类空肠弯曲菌感染有许多来源，但肉鸡和肉鸡肉已被证明是最重要的来源。为了实施有效的干预措施，降低肉鸡群中弯曲杆菌定植的概率，充分了解相关的风险因素至关重要。我们提出了一项跨国风险因素调查，该调查包括来自丹麦和挪威 5200 多个室内常规肉鸡群的空肠弯曲菌数据以及对标准化问卷的回答，问卷中包含来自 277 个丹麦和挪威农场的 40 多个解释变量。我们使用不同的丹麦和挪威数据组合探索了几种模型，包括使用单一国家数据集的模型。所有模型均使用向后消除和向前选择的广义线性模型进行分析。结果表明，挪威肉鸡群的定植风险低于丹麦肉鸡群。在两国中，增加肉鸡群定植空肠弯曲菌风险的农场特定变量为：肉鸡舍使用年限超过 5 年；停机时间（两批鸡之间的天数）较长，可能是由于停机时间较长导致对维持高水平生物安全的关注度降低；肉鸡舍没有单独的前厅或隔离区；以及使用带杯或铃铛的饮水器乳头，而不是不带杯的饮水器乳头。还确定了其他特定于国家的风险因素。对于挪威，随着农场鸡舍数量的增加，以及用于肉鸡的水来自地表水或钻孔而不是主水管，定植风险增加。对于丹麦，靴式浸渍或低饲养密度增加了鸡群呈空肠弯曲菌阳性的风险。不同的模型方法使我们能够探索利用大量数据来识别重要变量的效果。在很大程度上，国家特定模型确定的风险因素也存在于跨国模型中。然而，跨国模型比国家特定模型确定了更多的风险因素。这表明，合并来自两个国家的数据集并没有破坏结果，反而由于统计分析中获得的更大强度以及检查具有变量国家的交互项的可能性而受益。
