A longitudinal study of environmental salmonellaudcontamination in caged and free-range layer flocks

摘要

The environmental contamination by salmonella was examined over a 12-month period in 74udcommercial layer flocks from eight farms in the UK, which previously had been identified asudbeing contaminated with salmonella. Samples of faeces, dust, litter, egg belt spillage andudwildlife vectors were taken, plus swabs of cages, feeders, drinkers, floors, egg belts and boots.udSome sampling was performed in each month of the year. Numerous serovars were detectedudbut Salmonella Enteritidis was the only persistent serotype found among single-age flocks.udThere was a significant correlation between qualitative environmental samples and semiquantitativeudfaeces samples. The level of environmental contamination increased significantlyudover time. There were significant temperature and seasonal effects upon contamination.udWildlife vectors proved to be sensitive samples for the detection of salmonella. The efficacyudof cleaning and disinfection upon residual salmonella contamination, and upon subsequentudflock contamination, was highly variable between and within premises.udThe variability between detected prevalences over time and between flocks indicates audneed for regular, sensitive monitoring of flocks for salmonella to permit targeting of controludmeasures aimed at eliminating contamination of the layer environment by salmonella. Thereudis substantial scope for improvement of cleaning and disinfection procedures.