An exploratory study about contamination of pens of finishing pigs by ubiquitous Salmonella
Salmonella is one of the most common food-borne pathogens transmitted to humans and human salmonellosis is primarily caused by contaminated food. Porcine products have been identified as important food vehicles in outbreaks of salmonellosis (I, 2, 3). In France, the majority of Salmonella infected pig herds are sub-clinically infected. S. Choleraesuis does not occur and only ubiquitous serotypes are isolated (4). Sub-clinically infection is characterized by intermittent shedding of small numbers of Salmonella. In these sub-clinically infected pig herds, an infectioncontamination-infection cycle is maintained with mainly an endemic "house flora" of Salmonella enterica (5). When contaminated batches from these farms are processed on the slaughter line, slaughtering practices contribute to Salmonella dissemination and carcass contamination. Within batches, there is a strong correlation between the proportion of animals with Salmonella spp. in their feces and the proportion of contaminated carcasses at the end of the line (6, 7). As a result of subclinical Salmonella infection in pig herds, Salmonella contamination of pork carcasses constitutes a threat to human health. The influence of a wide range of factors on subclinical Salmonella contamination of pig farms is not well known. A good understanding of risk factors for Salmonella contamination of pig herds is an essential stake in order to avoid Salmonella spread within herds and between herds and slaughterhouses. Thus, the aim of this study was to investigate potential risk factors for the presence of ubiquitous Salmonella in the finishing sheds of farrow-to-finish farms in France.