Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 7, 3584 CL Utrecht, The Netherlands.
Vet Res. 2011 Feb 23;42(1):40. doi: 10.1186/1297-9716-42-40.
Human cases of bacterial gastro-enteritis are often caused by the consumption of eggs contaminated with Salmonella species, mainly Salmonella enterica serovar Enteriditis (Salmonella Enteritidis). To reduce human exposure, in several countries worldwide surveillance programmes are implemented to detect colonized layer flocks. The sampling schemes are based on the within-flock prevalence, and, as this changes over time, knowledge of the within-flock dynamics of Salmonella Enteritidis is required. Transmission of Salmonella Enteritidis has been quantified in pairs of layers, but the question is whether the dynamics in pairs is comparable to transmission in large groups, which are more representative for commercial layer flocks. The aim of this study was to compare results of transmission experiments between pairs and groups of laying hens. Experimental groups of either 2 or 200 hens were housed at similar densities, and 1 or 4 hens were inoculated with Salmonella Enteritidis, respectively. Excretion was monitored by regularly testing of fecal samples for the presence of Salmonella Enteritidis. Using mathematical modeling, the group experiments were simulated with transmission parameter estimates from the pairwise experiments. Transmission of the bacteria did not differ significantly between pairs or groups. This finding suggests that the transmission parameter estimates from small-scale experiments might be extrapolated to the field situation.
人类细菌性肠胃炎病例通常是由于食用了受沙门氏菌属污染的鸡蛋引起的，主要是肠炎沙门氏菌血清型肠炎（肠炎沙门氏菌）。为了减少人类接触的风险，在世界范围内的几个国家实施了监测计划，以检测受沙门氏菌感染的产蛋鸡群。采样方案基于鸡群内的流行率，并且由于其随时间而变化，因此需要了解肠炎沙门氏菌的鸡群内动态。已经在成对的产蛋鸡中量化了肠炎沙门氏菌的传播，但问题是在成对鸡中的动态是否与在更具代表性的商业产蛋鸡群中的传播相似。本研究的目的是比较成对和产蛋鸡群之间的传播实验结果。将实验鸡群分为每组 2 只或 200 只，以相似的密度饲养，每组分别有 1 只或 4 只鸡感染肠炎沙门氏菌。通过定期检测粪便样本中是否存在肠炎沙门氏菌来监测排泄情况。使用数学模型，根据成对实验中的传播参数估计模拟了群组实验。细菌的传播在成对和群组之间没有显著差异。这一发现表明，从小规模实验中得出的传播参数估计值可以外推到现场情况。
