USDA Research Documents Absence of Trichinella Infection in Commercial Pigs

Contact: Autumn Canaday
Email: Autumn Canaday

WASHINGTON, Aug. 2, 2024 – The U.S. Department of Agriculture today announced that Agricultural Research Service (ARS) scientists have documented the absence of infection by Trichinella, a parasite that once posed a major food safety risk in the commercial pork supply. ARS and the Animal and Plant Health Inspection Service (APHIS) conducted a national survey by sampling 3.2 million pigs raised under the U.S. Pork Quality Assurance Plus (PQA+) program and found zero animals infected with Trichinella. These results are consistent with international food safety guidelines for Trichinella to be considered a negligible risk for public health.

The United States does not perform post-slaughter testing for Trichinella in the pork supply. While modern production systems followed by U.S pork producers effectively minimize risk of exposure to this parasite, absence of Trichinella infection has never been verified through national testing. ARS researchers pursued this study to ascertain whether the PQA+ program eliminates the risk of Trichinella exposure in commercial pork, thereby addressing the demands of the U.S. export market.

The U.S. Pork Quality Assurance Plus (PQA+) program is an education and certification program designed by the U.S. pork industry to help pig farmers and their employees continually improve production practices. The program addresses food safety, animal well-being, environmental stewardship, worker safety, and public health. Many of the provisions for mitigating risk of Trichinella exposure are based on research conducted by ARS scientists. PQA+ includes five best management practices for prevention of exposure to Trichinella:

• Following proper feed biosecurity protocols.
• Preventing exposure to rodents, wildlife, and birds.
• Refraining from feeding raw food waste of animal origin to swine.
• Promptly removing and properly disposing of swine carcasses.
• Documenting animal arrivals and departures from PQA+ production sites.

In the ARS study, a total of 3,208,643 animals across twelve processing locations were tested over a period of 54 months. Parasites were not detected in any of the diagnostic samples, providing a 95% confidence in a Trichinella prevalence of less than 1 in 1,000,000 pigs. The occurrence of Trichinella in pork once posed a major food safety risk in many countries, justifying decades of effort expended on controlling this parasite. The data obtained from testing support the conclusion that pork from pigs managed under the PQA+ program do not pose a public health risk.

“The surveillance data support the assertion that the U.S. PQA+ program effectively mitigates risk for Trichinella infection in pigs,” said Dr. Benjamin Rosenthal, Research Leader of the ARS Animal Parasitic Disease Laboratory. “It is equally important to note that the data could be useful for future food safety decisions, including hazard analysis decisions.”

PQA+ guidelines and implementation details follow those for controlled management described by the World Organization for Animal Health and guidelines of the International Commission on Trichinellosis. Eleven U.S. pork processing companies, including 30 locations in 12 states, participated in the survey. There are currently more than 63,000 U.S. pork producers certified under PQA+.

This research, which is highlighted in this month’s issue of Food and Waterborne Parasitology, was supported by funding from the Animal and Plant Health Inspection Service, Agricultural Research Service, and the U.S. National Pork Producers Council.

The Agricultural Research Service is the U.S. Department of Agriculture's chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in U.S. agricultural research results in $20 of economic impact.