Observations related to the Salmonella EU layer baseline survey in the United Kingdom: follow-up of positive flocks and sensitivity issues
CARRIQUE-MAS JJ., BRESLIN M., SNOW L., ARNOLD ME., WALES A., McLAREN I., DAVIES RH.
<jats:title>SUMMARY</jats:title><jats:p>A follow-on study was carried out on 23 holdings identified as <jats:italic>Salmonella</jats:italic> positive in the 2004/2005 European Union (EU) baseline survey of <jats:italic>Salmonella</jats:italic> in laying hens. Eleven of 13 cage and 4/7 floor houses remained positive for <jats:italic>Salmonella</jats:italic> when the new flock was tested, and from 10/13 cage and 3/7 floor houses a <jats:italic>Salmonella</jats:italic> of the same serovar/phage type as found in the EU survey was isolated. There was a high correlation between the level of contamination in the houses at the time of the EU survey and in the follow-on flock. On seven occasions the house identified as positive in the EU survey was sampled after cleaning and disinfection but before a new flock was placed, and in all of them <jats:italic>Salmonella</jats:italic> could be isolated from the houses. The observed number of infected houses in infected holdings suggests that the holding-level prevalence in the United Kingdom would be about 21% higher than the results obtained in the EU survey.</jats:p>