The highly pathogenic avian influenza (HPAI) outbreaks on U.S. egg farms were the primary topic of discussion at the United Egg Producers Committee Briefings and Board Meeting at the Westin Hotel in Atlanta on January 23, 2023. The North American outbreak which started in early 2022 is still ongoing and has now claimed over 70 million head of commercial poultry in the U.S., Canada and Mexico, combined. Europe also suffered its highest number of birds lost due to HPAI in 2022 and recently outbreaks have occurred in commercial poultry flocks in South America.

With HPAI being found in North America in a wide variety of wild bird species in numbers greater than during the 2014-2015 outbreak, which was by far and away the worst outbreak on the continent up until that time, it is expected that the HPAI challenge will continue through the spring of 2023.

What have we learned?

David Suarez, DVM, acting laboratory director, Southeast Poultry Research Laboratory, USDA ARS, said at the Animal Health and Biosecurity Committee Briefing, that in general it takes less of the current North American H5N1 virus strain to cause an infection in chickens and turkeys than was required of the 2014-15 strain before it passed through domestic poultry. Suarez said “Most of the HPAI outbreaks were the result of farm-to-farm spread in 2014-15.” The virus in the 2014-15 epidemic became more contagious after it passed through domesticated poultry. During the current outbreak, only 15% of the outbreaks are believed to be the result of farm-to-farm spread.

At the present time, the H5N1 virus is much more widespread in wild birds and in a wider variety of wild birds than it ever was during the 2014-15 epidemic. The virus appears to be endemic in some resident wild bird species.

Oscar Garrison, senior vice president of food safety, UEP, said that UEP has requested permission for environmental swabs to be rapidly taken on non-negative layer and pullet farms to try and isolate the virus outside the house, in vents, fans and sidewalks. These swabs could help identify how the HPAI got into the house. Swabs done quickly, before the virus has time to spread throughout the house, may help identify the point of entry. Some in the layer industry suspect the virus is being introduced into the house in an aerosol form.

Some farms have popped positive twice in this outbreak. This is where they would do the audits. A couple of these farms were told that the producer should fix something and they didn’t before getting birds and had another positive.

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Fidelis Hegngi, DVM, senior staff veterinarian, Poultry Health Strategy and Policy, USDA APHIS, provided an overview of biosecurity and epidemiological risk factors in the current U.S. HPAI epidemic. Hegngi said, “People are the No. 1 vector for disease.” He explained that inanimate objects like equipment aren’t really disease vectors since people are responsible for bringing them on the farm and sometime bringing them in the poultry house.

Besides people, Hegngi said that common risk factors identified include:

  • Manure trucks on premises, 1 week prior to infection
  • Cleaning exhaust fans, in ways that allow sparrows in the poultry house
  • Proximity to ponds, lagoons, lakes and streams
  • Commingling of staff from different facilities, shared labor and contract crews (vaccination, catch crews, etc.)
  • Wild birds roosting near air intake
  • Co-location of main office, feed mill, egg trucks
  • Discrepancies in what is in the biosecurity plan versus what is actually being practiced

Hegngi said several U.S. egg producers invested in adding shower facilities on their farms in response to the 2014-15 HPAI epidemic. He said egg producers need to employ a person to take care of the shower facility. “Do not build a shower facility if it is not going to be used properly,” he said. “You need soap and hot water, if it isn’t clean and functioning people won’t use it.”

Finally, Hegngi stressed that egg producers need to be vigilant and everyone working at or visiting the facility should follow the farm’s biosecurity procedures. He suggested that egg producers develop incentives for workers who exhibit good biosecurity practices and habits. “Biosecurity is an investment not an expense,” he said.

Tracking where waterfowl roost

Maurice Pitesky, DVM, associate specialist in cooperative extension, school of veterinary medicine, University of California, Davis, explained how the Waterfowl Alert Network has been created to show where waterfowl roost in the U.S. Radar and satellite data are used to identify where waterfowl roost, which Pitesky said occupies the birds for around 14 hours each day. He said the system can be used to show which poultry farms are within 4 kilometers of where large groups of waterfowl roost. He explained that waterfowl will travel up to 4 kilometers from their roosting site to forage for food.

Pitesky said the plan is to develop the Waterfowl Alert Network into a national system for daily predictions of the locations of waterfowl in large numbers to protect the U.S. broiler, turkey and layer industries. Poultry producers can sign up for the service for a monthly fee and it tracks waterfowl from November through May each year.