A new study investigating a multistate outbreak of multidrug-resistant Salmonella infections linked to pig ear pet treats highlights the interconnectedness of human health and pet ownership, emphasizing the need for stringent surveillance of pet food products.

The study was funded by the Food and Drug Administration’s Animal Feed Regulatory Program Standards and the FDA’s Veterinary Laboratory Investigation and Response Network (Vet-LIRN).

From June 2015 to Sept. 2019, 154 human cases of Salmonella infection were reported across 34 states. The investigation identified seven Salmonella serotypes genetically related to samples from pig ear pet treats. Whole genome sequencing (WGS) of isolates was used to predict antimicrobial resistance. Notably, 107 of 122 patients interviewed reported dog contact, and 65 of 97 reported contact with pig ear pet treats. Salmonella was isolated from 137 pig ear treats, including imports from Argentina, Brazil, and Colombia, and from four dogs. WGS predicted that 77 percent of human isolates and 43 percent of pig ear treat isolates were resistant to three or more antimicrobial classes.

Investigation findings

The study, published in the journal Lancet Public Health, examines the first documented multistate outbreak in the U.S. linked to pig ear pet treats. The outbreak investigation involved multiple agencies, including the CDC, FDA, and state health departments, tracing the sources of contaminated pig ear treats and evaluating their antimicrobial resistance profiles.

Pig ear treats and dogs were tested for Salmonella by state officials and the FDA. Products were traced back to their countries of origin when possible. Contaminated pig ear treats were found to be imported by three pet treat companies from South America, resulting in nationwide recalls by six suppliers.

Impact and public health implications

The outbreak involved 154 human cases, with 107 patients reporting dog contact. The investigation revealed that both direct contact with pig ear treats and zoonotic transmission from dogs contributed to the spread of Salmonella. The study highlights the risk posed by contaminated pet treats and the potential for such products to transmit antimicrobial-resistant bacteria to humans.

Regulatory and preventive measures

Pet treats like pig ears are regulated by the FDA under the Federal Food, Drug, and Cosmetic Act, which requires all animal foods to be safe, produced under sanitary conditions, and free of harmful substances. However, the investigation found that pre- and post-processing pathogen reduction efforts were insufficient in this case.

The study also noted that pig ear treats labeled as irradiated were still found to be contaminated with Salmonella. Irradiation is a method used to reduce pathogen burden without heating the product. The effectiveness of irradiation on pet treats derived from dried animal byproducts, like pig ear treats, has not been well studied.

Recommendations

The investigation emphasizes the need for intensified surveillance of internationally traded pet food products for foodborne pathogens. It also calls for international producers to bolster strategies that reduce product contamination. Pet owners should be made aware of the disease risks associated with pig ear pet treats and take appropriate precautions, such as handwashing after handling pet foods or treats.

The outbreak illustrates the widespread risk to pets and pet owners from contaminated pig ear treats. The study identified multiple Salmonella serotypes and antimicrobial resistance profiles, underscoring the need for coordinated mitigation efforts across state and federal agencies.

This outbreak of multidrug-resistant Salmonella linked to pig ear pet treats highlights the interconnectedness of human and animal health. It underscores the need for stringent surveillance and regulation of pet food products to prevent future outbreaks. Consumers should be aware of the potential health risks and take measures to protect themselves and their pets.

More information about this study and its findings can be found here.

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