Overview and summary of the Food Safety and Inspection Service risk assessment for Salmonella enteritidis in shell eggs, October 2005.

In 1998, the United States Department of Agriculture's Food Safety and Inspection Service (FSIS) and the Food and Drug Administration completed a risk assessment that indicated multiple interventions along the farm-to-table chain were needed to reduce the risk of human illness from Salmonella Enteritidis in shell eggs. Based on newly available data and improved modeling techniques, FSIS completed an updated risk assessment to examine the effect of pasteurization and refrigeration on reducing human illnesses from S. Enteritidis in shell eggs. The risk assessment model was written in Visual Basic for Applications (Microsoft, Redmond, WA) and run using Monte Carlo methods. The model estimated that if all shell eggs produced in the United States were pasteurized for a 3-log10 reduction of S. Enteritidis, the annual number of illnesses from S. Enteritidis in eggs would decrease from approximately 130,000 to 40,000. Pasteurization for a 5-log10 reduction of S. Enteritidis was estimated to reduce the annual number of illnesses to 19,000. The model also estimated that if all eggs produced in the United States were stored and held at 7.2 degrees C within 12 hours of lay, the annual number of illnesses from S. Enteritidis in eggs would decrease from 130,000 to 28,000. As a result, rapid cooling and pasteurization of shell eggs were predicted to be highly effective mitigations for reducing illnesses from consumption of S. Enteritidis in shell eggs.

Estimate of illnesses from Salmonella enteritidis in eggs, United States, 2000.

Results from our model suggest that eating Salmonella enterica serovar Enteritidis-contaminated shell eggs caused 182,060 illnesses in the United States during 2000. Uncertainty about the estimate ranged from 81,535 (5th percentile) to 276,500 illnesses (95th percentile). Our model provides but 1 approach for estimating foodborne illness and quantifying estimate uncertainty.

Surveys of Salmonella enteritidis in Unpasteurized Liquid Egg and Spent Hens at Slaughter.

In a 1995 national survey of 937 unpasteurized liquid egg samples collected in breaker plants, 179 of 937 samples (19%) were Salmonella enterica serotype Enteritidis ( S. Enteritidis ) positive. The proportion of unpasteurized liquid egg samples positive for S. Enteritidis was highest in the Northern Region where 106 of 267 samples collected (40%) were S. Enteritidis -positive. These Northern Region results were over three times the S. Enteritidis prevalence detected from the other three regions, whose results ranged between 10% and 12% S. Enteritidis -positive samples. In a 1995 national survey of spent hens at slaughter, 136 of 305 flocks (45%) had at least one S. Enteritidis -positive pooled sample detected. Flock prevalence was highest in the Northern and Central Regions (64% and 40%, respectively); Southeastern and Western Regional flock prevalence levels were much lower (17% and 23%, respectively). A comparison of the 1991 and 1995 unpasteurized liquid egg and spent hen results suggest there has been no decline in S. Enteritidis occurrence in the commercial egg industry between 1991 and 1995. Salmonella Enteritidis phage type 4 was detected in the 1995 surveys of both spent hens and unpasteurized liquid egg but was not found in either survey in 1991. With the exception of one liquid egg sample from the Southeastern Region, S. Enteritidis phage type 4 was found only in the Western Region of the U.S. S. Enteritidis phage type 4 has emerged in the egg industry in the Western U.S. concurrently with an increase in the number of sporadic human phage type 4 isolates in California and Utah.

Bacteria on Beef Briskets and Ground Beef: Correlation with Slaughter Volume and Antemortem Condemnation.

Aerobic plate counts of 3,455 brisket and 1,370 ground beef samples were examined for association with slaughter volume in 547 U.S. beef slaughter establishments. In general, high-volume beef slaughter establishments control total aerobic bacteria counts on briskets and ground beef more effectively than small volume establishments. The lower Aerobic plate counts at high slaughter volumes may have resulted from uniformity of cattle slaughtered, specialization of labor, measures taken to prevent contamination, and effective decontamination of carcasses in high-volume slaughter establishments. In this study the prevalence of Salmonella contamination was found to be more closely associated with the health of animals brought to slaughter than with certain conditions in the slaughter establishments. The prevalence of contamination of brisket and ground beef samples with Salmonella was highest in calf slaughter establishments. Salmonella contamination on brisket samples increased as antemortem condemnation increased in establishments that slaughter calves. No association was found between Salmonella contamination and slaughter volume.