A Dutch study from the Institute for Risk Assessment Sciences, Faculty of Veterinary Medicine, Utrecht University, analysed transmission pathways of Salmonella through the pork slaughter line.

The research team of J.H. Smid, A.H.A.M. van Hoek, H.J.M. Aarts, A.H. Havelaar, L. Heres, R. de Jonge and A. Pielaat proposed a model to link Salmonella serovars to contamination sources.

The study, Quantifying the sources of Salmonella on dressed carcases of pigs based on serovar distribution, published in Meat Science, showed that house flora was an important source of Salmonella for contaminated carcasses and the relevance of different Salmonella sources varied within and between days.

Salmonella serotyping data, qualitatively described by van Hoek et al. (2012), were used to quantify potential sources of Salmonella in a Dutch pig slaughterhouse.

Statistical tests to compare per-day Salmonella prevalence and serotyping data from multiple points in the chain were used to find transmission pathways.

A statistical model based on serotyping data was developed to attribute Salmonella on dressed carcasses to the most likely source.

Approximately two-third of dressed carcasses carrying Salmonella on the medial surface had been contaminated by house flora.

For carcasses carrying Salmonella on the distal surface, transient Salmonella from incoming pigs was a more important source.

The relevance of the different sources of Salmonella varied within and between sampling days.

Results were compared to those of another modelling approach, in which Salmonella concentration data from the same samples were used (Smid et al., 2012). They mostly agreed.

The study found that the approach chosen by an individual slaughterhouse depends on the data that are collected.

August 2014