Ekelijn Thomas, Annemarie Bouma and Don Klinkenberg of Utrecht University in the Netherlands have compared transmission characteristics of Salmonella enterica serovar Enteritidis between pair-housed and group-housed laying hens in a paper published in the journal, Veterinary Research.

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), explain Thomas and colleagues. To reduce human exposure, in several countries worldwide surveillance programmes are implemented to detect colonised 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, say the researchers, was to compare results of transmission experiments between pairs and groups of laying hens.

Experimental groups of either two or 200 hens were housed at similar densities, and one or four hens were inoculated with Salmonella Enteritidis, respectively.

Excretion was monitored by regularly testing of faecal samples for the presence of Salmonella Enteritidis.

Using mathematical modelling, the group experiments were simulated with transmission parameter estimates from the pair-wise experiments.

Transmission of the bacteria did not differ significantly between pairs or groups. Thomas and co-authors, therefore, concluded that the transmission parameter estimates from small-scale experiments might be extrapolated to the field situation.

Reference

Thomas E., A. Bouma and D. Klinkenberg. 2011. A comparison of transmission characteristics of Salmonella enterica serovar Enteritidis between pair-housed and group-housed laying hens. Veterinary Research 2011, 42:40. doi:10.1186/1297-9716-42-40

Further Reading

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You can view the full report (as a provisional PDF) by clicking here.

March 2011