EFSA News Item, 14 June 2006
The EFSA Journal (2006) 81, 1-71, “ Preliminary Report on the Analysis of the Baseline Study on the Prevalence of Salmonella in Laying Hen Flocks of Gallus gallus”
NOTE: The following note was published by the EFSA:
This is a preliminary report on the analysis of the Community-wide baseline study to estimate the prevalence of Salmonella in laying hen flocks. It is being published pending the full analysis of the entire dataset from the baseline study. The report contains the elements necessary for the establishment of the Community target for reduction of Salmonella in laying hens in accordance with Article 4 of Regulation No 2160/2003 of the European Parliament and of the Council on the control of salmonella and other specified food-borne zoonotic agents. Although the final report will not be published until October 2006, key data such as the prevalence levels of salmonella in laying hens is not foreseen to change significantly with the publication of the final report which will contain the full analyses and results from the study. As the European Commission intends to set targets prior to publication of the final report, EFSA is publishing the preliminary analysis in keeping with its policy of openness and transparency.
Summary of the Preliminary Report
An EU-wide Salmonella baseline study was conducted on commercial large-scale laying hen holdings with at least 1,000 laying hens in the flock. The study was carried out in all the Member States, and the sampling of the holdings took place during the period of 1 October 2004 to 30 September 2005 . Norway participated in the study on a voluntary basis.
The aim of the study was to estimate the Salmonella holding observed prevalence at the global EU-level as well as for each Member State specifically. In total, 5,317 laying hen holdings in the EU were included in this study. But a clean dataset comprising 4,797 holdings was mainly used to analyse the results. Samples were taken from flocks of laying hens during the last nine weeks of their production. One flock per each holding was sampled by taking five faeces samples and two dust samples.
The results show that at the global EU-level 20.3% of the large-scale laying hen holdings are bacteriologically positive for Salmonella Enteritidis and/or Salmonella Typhimurium. The Member States' -specific Salmonella Enteritidis – Salmonella Typhimurium holding observed prevalence estimates varied largely, from a minimum of 0% to a maximum of 62.5%.
The holding observed prevalence for any Salmonella subspecies was, in general, higher. At the global EU-level the presence of any Salmonella spp. was detected in 30.7% of the large-scale laying hen holdings. The range of the Member States' - specific Salmonella spp. holding observed prevalence was also wide, from a minimum of 0% to a maximum of 79.5%.
The number of positive samples in a holding varied between 1 and 7, and an important proportion of the holdings was found positive on the basis of only one or two positive samples.
Based on preliminary univariate analysis, holdings having Salmonella Enteritidis vaccinated flocks were less likely to be positive for Salmonella Enteritidis, in eight countries where both flocks vaccinated and unvaccinated against Salmonella Enteritidis were sampled. But with the subgroup of Salmonella Enteritidis positive holdings in these countries, there was no difference in the proportion Salmonella Enteritidis positive samples between vaccinated and unvaccinated flocks. Covered by the clean dataset, dust samples were found more positive for Salmonella Enteritidis and/or Salmonella Typhimurium than faeces samples. Medication with antibiotics within two weeks prior the sampling did not seem to have an impact on the results for Salmonella Enteritidis and/or Salmonella Typhimurium.
The full Preliminary Report is available on the EFSA web site at:
http://www.efsa.eu.int/science/monitoring_zoonoses/reports/1541/zdc_salmonella_report_ej81_layinghens_en1.pdf