A review of current knowledge on Salmonella control on-farm and within the processing plant, February 2011

Literature review

This literature review has highlighted that there are several factors associated with Salmonella presence on-farm and that there is an urgent need to identify the point of infection on Northern Ireland farms to enable known effective control measures to be implemented. It has also shown that the serological ELISA test is useful in providing information of Salmonella presence on-farm but that it is of limited use in identifying high-risk pigs at slaughter.

A recommendation of this literature review is to identify a list of factors associated with Salmonella prevalence on-farm in order of priority – this will be completed through a comprehensive producer questionnaire. It is also planned to identify the point of infection on Northern Ireland farms through the completion of a longitudinal study. Once these tasks have been conducted, intervention control measures will be assessed.

Within the processing plant the Salmonella carriage at time of slaughter will be quantified to define the prevalence in Northern Ireland herds and also indicate if some pigs present a significantly higher risk than others. The Slaughterhouse Hygiene Tool will be used and correlated with actual microbial contamination. This exercise will provide information on where to target intervention control measures and will ultimately reduce the risk of Salmonella contamination within pork products.

Recommendations for on-farm research

• To identify the point of infection on NI farms through scientific longitudinal studies on representative farms. This will be achieved through the use of ELISA testing of blood samples from sows and pigs from weaning to slaughter and through bacteriological testing of faecal samples.
• To identify factors which contribute to Salmonella prevalence on-farm. The literature indicates that these factors can be identified through the use of a comprehensive producer questionnaire and listed in order of priority through the development of a statistical model.
• To develop and validate targeted on-farm control strategies to reduce Salmonella prevalence. The strategies will be focussed on the point of infection identified from the longitudinal studies and on modifying management practices which influence Salmonella infection identified through the questionnaire.

Recommendations for processing plant research

• To establish the bacterial status of herds entering the processing plants by direct faecal sampling of gut contents on the processing line and to compare with the results of the longitudinal farm studies to further define the apparent point of infection.
• To investigate the level of carcass contamination within the two main processing plants in Northern Ireland and to assess the hygiene throughout the processing line.
• To correlate carcass contamination and processing line hygiene with the level of risk modelled by the Hygiene Tool.
• To introduce effective control measures and interventions at high risk points throughout the line. Ultimately the actual focus areas will be identified by the investigation to determine the level of carcass contamination and hygiene status throughout the line.