INTERVENTION STRATEGIES FOR SALMONELLA-ENTERITIDIS IN POULTRY FLOCKS - A BASIC APPROACH

Poultry laying flocks can become infected with Salmonella enteritidis by several routes. In this study a model is presented of the cumulativ e infection curve of S. enteritidis in laying flocks. Based on this mo del and practical results the contribution of different routes to the infection can be estimated providing a basis for an effective interven tion strategy. For illustration, the cumulative infection curve of S. enteritidis in Dutch laying flocks is analysed. This curve shows a low level of infection at the start of the laying period which indicates that the contribution of the vertical infection route (from infected b reeding flocks to progeny) is small. The course of the infection curve indicates that there is a high probability of infection in the first part of the laying period. The result suggests that the laying flocks become infected mainly from the farm environment including not properl y cleaned and disinfected poultry houses and infected vermin present o n the farm. As a consequence, intervention in The Netherlands should b e directed to trace S. enteritidis-contaminated laying farms and eradi cate the contamination.