After the “incredible scope” of the worst bird flu epidemic ever to hit the nation earlier this year, the USDA’s plan for reducing the risk of an outbreak this fall includes swift culling of infected flocks with a bird-flu vaccine available “as a possible adjunct to, and not a replacement for, a future eradication effort.” The usual response to discovery of highly pathogenic avian influenza is to quarantine the affected farm and its surroundings and kill the infected flock to prevent spread of the virus.
“We are prepared to depopulate all affected flocks within 24 hours of preliminary diagnosis,” said the USDA in its preparedness plan. That would be a speedier response than the epidemic during the first half of the year. Destruction of flocks within 24 hours is considered optimal in halting the virus.
If need be, the department said it would approve “the use of ventilation shut-down for depopulation” when the standard methods of euthanizing fowl by carbon dioxide gas or covering them with foam are too slow. “While not a preferred method, it could save the lives of thousands of birds by reducing the risk of disease spread.”
A ventilation shutdown means turning off ventilation fans and closing airways into a poultry barn so birds die of heat stress. A USDA official told Reuters that birds would die within 30 to 40 minutes; the Humane Society of the United States criticized a ventilation shutdown as a “miserable and protracted means of euthanasia” that “essentially bakes the birds to death.”
“We intend to use AI [avian influenza] vaccines as a possible adjunct to, and not a replacement for, a future eradication effort,” said the USDA. “The strategy for vaccination would be a suppressive emergency approach, where commercial poultry in a defined geographic area with rapidly spreading disease would be vaccinated.” Several factors would be weighed before the vaccine is used, including whether other efforts to control the disease were working, the sector of the industry that was affected, and the likely impact on domestic and international supplies and trade.
U.S. trading partners are likely to ban imports of U.S. poultry and products if a vaccine is used while they assess the medication’s effectiveness. Billions of dollars in sales would be jeopardized.
Wild waterfowl are blamed for spreading the disease last winter and spring. Nearly 49 million birds, mostly turkeys and egg-laying hens, were lost during the first half of the year. U.S. egg prices are at record highs in grocery stores as a result of the epidemic.
In a statement, the USDA said it was confident that its surveillance programs for illness in wild birds and commercial flocks – which it called “the strongest in the world” – “will enable us to detect the disease early,” and that its work with states and the poultry industry to prepare for a potential outbreak “will help quickly contain the disease.”
More stringent biosecurity procedures are fundamental, says the USDA plan, because of evidence of farm-to-farm spread of bird flu by humans as well as birds. “All likely sources of virus introduction should be mitigated and producers should work to minimize the risk of spread between poultry operations and between individual houses on the same operation.”
The USDA anticipates it will collect and test more than 40,000 samples from wild birds for the bird flu virus during the year ending next June 30. It also boosted its capacity for handling samples from poultry operations.