USDA finding Salmonella less often in meat

Amy L. Becker

Aug 10, 2004 (CIDRAP News) – The general trend for Salmonella in meat and poultry samples tested by the US Department of Agriculture (USDA) continues to head downward, the USDA's Food Safety and Inspection Service (FSIS) announced on Aug 5.

FSIS collects and analyzes Salmonella samples at slaughter and grinding plants to verify compliance with the Hazard Analysis and Critical Control Point (HACCP) rule, which set performance standards for seven categories of meat and poultry products. Those products are broilers, market hogs, cows and bulls, steers and heifers, ground beef, ground chicken, and ground turkey.

Despite variations in individual categories, Salmonella frequencies in all classes of products have dropped to levels well below the estimated baseline prevalence before the HACCP system was launched in the late 1990s, according to the FSIS. However, the testing program was designed to track establishment performance and may not reflect the true nationwide occurrence of Salmonella in these products, the agency cautioned.

Of 49,868 random regulatory samples collected in 2003, 3.8% overall tested positive for Salmonella, down from 4.29% in 2002. That drop continues a longer-term trend: 5.03% in 2001, 5.31% in 2000, 7.26% in 1999, and 10.65% in 1998.

The results for each product are further divided into categories based on the size of the establishment. In individual categories (all sizes of plants), the prevalence dropped from 2002 for market hogs, cows and bulls, and ground beef, but there was a 0.1% increase for steers and heifers.

Despite the overall downward trend, FSIS officials voiced concern about increases in positive Salmonella tests in all three poultry categories. The Salmonella prevalence in broilers from all sizes of businesses increased from 11.5% in 2002 to 12.8% in 2003, though it remained below the baseline prevalence of 20%. Large ground-turkey and small ground-chicken establishments also saw increases.

The FSIS said it would examine data from 1998 to the present to identify plants with "negative performance trends." Investigators then will conduct in-depth HACCP and sanitation verification reviews at those sites "to help ensure this one-year increase does not continue," the agency's news release said.

In citing the limitations of the data, the FSIS said different establishments may be sampled from year to year, preventing rigorous trend analyses. While the pre-HACCP baseline estimates of Salmonella prevalence were nationally representative because they were weighted on the basis of the production volume of the sampled plants, the HACCP figures represent unweighted test results.

The downward trend in Salmonella in tested meat seems to parallel a trend in salmonellosis cases reported by the Centers for Disease Control and Prevention (CDC). The CDC estimated in April that the incidence of salmonellosis declined 17% from 1996 to 2003.

The CDC's Foodborne Diseases Active Surveillance Network, or FoodNet, which covers about 14% of the US population, reported 6,017 laboratory-confirmed salmonellosis cases in 2003, or 14.5 cases per 100,000 people. Those cases come from all or parts of the nine states that make up FoodNet's surveillance area. While FoodNet's numbers are the most detailed data available, the CDC noted that they may not accurately represent nationwide illness patterns. In addition, many foodborne illnesses are not lab-diagnosed.

Full FSIS report
http://www.fsis.usda.gov/PDF/Salmonella_Progress_Report_1998-2003.pdf

CDC report on incidence of common foodborne illnesses in 2003
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5316a2.htm