#07-079

Complete

Date Full Report Received

06/30/2008

Date Abstract Report Received

06/30/2008

Investigation

Institution:
Primary Investigator:

We developed a farm-to-illness risk assessment to investigate the risk of human salmonellosis from the consumption of fresh pork. The risk assessment explores major issues in both pre-harvest and post-harvest pork safety including on-farm transmission of Salmonella, the effect of various slaughter processes on both the prevalence and the level of the pathogen, and the persistence of contamination through distribution, storage, and preparation. The model is a probabilistic simulation capturing the real-world variation that is inherent in pork production systems. The risk assessment tracks the prevalence and level of salmonella contamination on carcasses through grow-out, multiple stages of slaughter, retail and consumer storage and consumer cooking in the home environment. The result is a prediction of the level of salmonella ingested by an individual from the consumption of a serving of pork. The probability that this will result in salmonellosis is finally estimated. Model results estimate that the risk of salmonellosis from the consumption of fresh pork meat products prepared in the home is 8×10-7 (mean estimate), which translates to 0.8 illnesses per million servings. Based upon available consumption data, we estimate this would result in 8,120 cases of salmonellosis per year in the US. (Note that the scope of the work included only fresh pork meat products, and does not include RTE or mixed meat products, or those prepared outside the home).
Since the specific values of the inputs on which the model is based (for example prevalence of Salmonella in weaners), can be varied to explore the effect of different control measures, scenario analysis permits a comparison of these approaches in terms of their ultimate impact on the risk of illness. Model analyses indicate that key parameters in the pork production chain that have a strong influence upon the risk of illness are:
• the between herd and within herd prevalence at slaughter,
• the change in prevalence that occurs during lairage,
• the amount of gut contents added to a carcass during evisceration if rupture of the viscera occurs.
Of less importance in controlling the risk of illness are:
• The cross contamination that occurs during scald
• Probability of external contamination on pigs at slaughter that are not infected with salmonella.
This project is of interest to stakeholders at all stages of the pork production chain.