Environmental contamination and detection of Salmonella enterica serovar enteritidis in laying flocks.

Faecal, dust and other environmental samples were collected from the floors, droppings belts, egg-collection systems and other areas of 14 cage-layer flocks, 10 barn egg production flocks and seven free-range flocks, and cultured for Salmonella species. The distribution of the organism varied with its prevalence and with the vaccination status of the birds. No one sample type was found to be suitable for identifying all contaminated houses. Salmonella was also frequently found on egg-packing equipment and in samples from rodents and wild birds.