Salmonellosis is the 2nd most common cause of human bacterial food poisoning and can be acquired from meat or eggs, either via direct consumption or cross-contamination in the kitchen. The European Commission has set the criteria to control Salmonella infections within the poultry sector and it is proposed that the swine sector should follow. Pork is considered, after eggs, the major source of infection in humans in the EU, with Salmonella typhimurium, including monophasic strains, being frequently implicated. Good control measures at the farm level are likely to correspond with lower prevalence of Salmonella infection and, subsequently, a reduction of cross-contamination of carcasses processed at the slaughterhouse and a reduction in human salmonellosis. This review focuses on biosecurity measures in pig farms that can help to control important pig diseases at the same time as reducing the within-herd prevalence of Salmonella. This information is likely to provide an economic incentive for farmers to apply improved general standards of farm biosecurity and hygiene management that would have a positive impact in food safety.

Aims: The control of Salmonella in pig production is necessary for public and animal health, and vaccination was evaluated as a strategy to decrease pig prevalence.

Anecdotal evidence has suggested that outdoor-kept pigs show an improvement to health and productivity after being moved to a new site. This study explores whether Salmonella occurrence reduced and was sustained after moving to a new site. Nine farms were followed for a year in which four sampling visits were completed. The highest detection of Salmonella was from pooled faecal dropping from pigs, run-off/ pooled water, rodents and wild birds. Descriptive summaries showed that the prevalence of both all Salmonella and serovars of public health importance were lower at all visits after the move. Some variability was shown in results from individual farms, but a year after the move, six farms still maintained a lower prevalence. A risk factor model showed that the prevalence at visits 2 and 3 after the move was significantly lower than baseline, after accounting for a number of significant factors that were included in the model. These were sample type and seasonality (included as a priori), presence of coughing in the sampled group and Glasser's disease on the farm, and the use of tent or kennel accommodation. This finding provides important evidence that more frequent site moves may help reduce Salmonella prevalence in outdoor herds.

Salmonella prevalence in UK pigs is amongst the highest in Europe, highlighting the need to investigate pig farms which have managed to maintain a low Salmonella seroprevalence. A total of 19 pig farms that had a consistently low (<10%) seroprevalence over 4 years (named Platinum farms) were compared against 38 randomly selected Control farms, chosen to match the same distribution of production types and geographical distribution of the Platinum farms. Each farm was visited and floor faeces and environmental samples were collected. It was shown that Control farms had a significantly higher median percentage of pooled faecal samples positive for Salmonella compared with the Platinum farms (12.1% and 0.4% for pooled faecal samples, respectively) and were more likely to have serovars of public health importance detected (S. Typhimurium/ monophasic variants or S. Enteritidis). Considering the comprehensive on-farm sampling, the identification of farms negative for Salmonella, along with the identification of those that had maintained low prevalence over a long period is important. The risk factor analyses identified pelleted feed, feed deliveries crossing farm perimeter and regular antibiotic use as associated with being a Control farm. Performance data indicated that Platinum farms were performing better for slaughter live weight than Controls. Limited assessments of available pig movement records suggested that the source of pigs was not key to Platinum status, but further study would be needed to confirm this finding. These results emphasise that maintaining very low prevalence on UK farms is achievable.

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