A study of the dynamics of Salmonella infection in turkey breeding, rearing and finishing houses with special reference to elimination, persistence and introduction of Salmonella.
Mueller-Doblies D., Carrique-Mas JJ., Davies RH.
In this descriptive study, the dynamics of Salmonella infection of turkey flocks were investigated by repeated sampling of houses where Salmonella had been identified. The aim of the study was to identify the most common scenarios involved in elimination, persistence and introduction of Salmonella in the different branches of the turkey industry. Sixty-two houses on 34 turkey farms (comprising breeding, rearing and finishing farms) were sampled longitudinally, starting with the identification of a positive flock. A total of 117 follow-on flocks were tested and cleaning and disinfection (C&D) was assessed during 66 post-C&D visits. A total of 155 incidents (clearance, persistence or introduction of Salmonella) were recorded. Persistence was seen in 35.5% of incidents and was seen more frequently in breeding and rearing houses compared with finishing houses. Most persistence incidents were the result of insufficient C&D. Clearance was seen in 40% of incidents and was more often observed in finishing houses than in breeding or rearing houses. Introduction was seen in 24.5% of incidents and was more common in breeding and finishing flocks than in rearing flocks. Contamination of a house with Salmonella Typhimurium was more likely to be cleared compared with other serovars. The total number of positive samples found at a post-C&D visit was correlated with the probability of carry-over of infection, whereas the location of the positive samples seemed to be less important. Our highly sensitive post-C&D sampling method allowed us to predict a negative follow-on flock in most cases.