The Correlation Between Pig Health and Human

NON-TECHNICAL SUMMARY: Currently there is intense debate over antibiotics in food animal production, arising from the possibility that antibiotic use at the herd or flock level, or at low doses for long periods of time, could produce resistant foodborne bacteria resulting in human health harm. These concerns have resulted in regulatory actions in the U.S. and other countries. Hurd et al just completed a study showing that fecal carcass contamination in the bung and pleural cavities with Campylobacter and Enterococcus spp. is correlated with pathology in the pleural cavity of slaughter pigs. To improve studies like this, many more data are needed, requiring reliable, repeatable and simple methods of assessing pig health during high speed slaughter. We propose development and refinement of a veterinary pathologist-verified organoleptic method for assessing pig health that can be routinely performed by plant personnel.<P>APPROACH: A large, integrated pork processing operation in the Midwest has granted us access to market pigs at slaughter for previous studies and for this study. Sampling A form of case-control study design will be used due to the expected low frequency of pathologies. Our previous study found only 186 peel-outs out of 2,625 (7%) pigs observed (2). Data will be collected in a high speed pork slaughtering facility during daily operations. For each replicate, sample collection will begin at the same time of day, preferably early in the morning to avoid secondary contamination of carcasses due to machinery. Data collectors will be located on-line at the point of viscera removal. When adhesions or other lesions are noted by plant personnel or by the USDA inspector, the viscera will be marked for lesion scoring (case). Once the viscera have been inspected by the USDA, it will be evaluated by a pathologist-trained data collector. A comparison animal (control) will be picked for the same evaluation 10 to 20 carcasses after the case. The extended length of time after case identification is to allow time for lesion scoring on the case as well as to prevent downstream carcass contamination that might have occurred due to impaired evisceration of the case carcass. The control carcass will be evaluated in the same manner as the case. Because the specific carcasses with visible pathology are being cultured for bacterial contamination, this study provides a far more accurate method to assess the level of correlation between carcass contamination and peel-outs than what was accomplished in our previous study. From the following two methods, (pathologists scoring and organoleptic measures) we can compare the sensitivity of the lay persons (plant personnel who routinely assess carcasses at slaughter for health measures such as peel-outs) and a trained veterinarian to the actual prevalence of animal disease. Our previous project showed statistically significant correlations between peel-outs and contamination of the pleural cavity just before final rinse. Final rinse is considered the last HACCP step in slaughter. This is a good point to measure the risk of the final slaughter product before the meat enters the human food supply. Therefore, we will focus our efforts on testing at this location. Correlation and logistic regression methods will be employed to test the relationship between variables. This analysis will demonstrate the strength of the relationship between animal health and human risk, and could provide significant insights as to the relation to on-farm animal health and the usefulness of antibiotics in producing a healthier animal and a potentially safer human food product.<P>
IMPACT: 2007/01 TO 2007/12<BR>
Antibiotic resistance derived from mass medication of food animals is thought to threaten public health and the use of human antibiotics. However, antibiotic use in food animals generally results in healthier animals which may be a public health benefit. In this study, subclinically ill pigs with lung peel-outs were thought to have a higher incidence of fecal contamination, which would directly relate to human health. 358 pigs were swabbed, photographed and cultured for fecal bacteria. Three veterinary pathologists viewed the photographs and scored the severity of lesions on carcass and heart. We found that Salmonella contamination of the carcass was more than two times as likely in pigs with evidence of lung adhesions. Multivariate analysis is being completed. Our data provides evidence that subclinically ill pigs with lung peel-outs are more likely to contaminated with Salmonella, and therefore, indicate an increased risk of foodborne illness in humans. Will provide data for critical risk assessments and public policy.