Avian influenza (AI) and Newcastle disease (ND) are poultry diseases of great concern to the poultry industry. The viruses that cause these diseases can be killed by heat. But the exact parameters for inactivating them by pasteurization had not been established—until now.
Agricultural Research Service (ARS) scientists have shown that the same industry-standard pasteurization temperatures and times established for Salmonella inactivation in egg products can also kill AI and ND viruses.
Pasteurization is a short-term, low-heat process used to kill bacteria in milk, egg products, and other food items without changing the cooking properties or flavor of the food.
David Swayne, laboratory director of the Southeast Poultry Research Laboratory in Athens, Georgia, found that AI and ND viruses could be destroyed by pasteurization. He determined that heat inactivation occurred from 55°C to 63°C. The time needed to inactivate the viruses depended on virus strain and egg product.
“While there are studies indicating that these viruses can be transmitted to birds by ingestion, there are no definitive results showing the same is true for humans. But inactivating the viruses in egg products will preclude possible transmission to humans.”
Swayne artificially infected four commercial egg products with two AI viruses (one with low pathogenicity and one with high pathogenicity) and three ND viruses (two with low virulence and one with high virulence). He then subjected the products to standard, recommended pasteurization temperatures and times and found them to be effective at killing the viruses.
“This study is important because we were able to determine inactivation curves for various temperatures and times for future reference,” says Swayne.
In 2002, more than $322 million of processed egg products were traded internationally. Exporting countries must provide assurances that their products are free from specific infectious agents that could severely affect poultry health.
Through this work, ARS has now shown that, with pasteurization, egg products potentially infected with AI and ND viruses can be safely exported and used for food consumption, thereby increasing international trade and improving food safety.