Keeping flocks safe from avian influenza

CHAMPAIGN, Ill. — Over 35 million birds, mostly egglayers, have been lost in the United States by highly pathogenic avian influenza since Jan. 1.

Since 2022, HPAI has affected over 166 million birds including 127 million egglayers. That’s an average loss of 42.3 million eggs per year, or about 11% of the five-year average annual layer inventory of 383 million hens since the outbreak began, according to the U.S. Department of Agriculture.

Challenges and solutions to reduce the spread of HPAI were outlined by Mark Ernst, Illinois Department of Agriculture state veterinarian, in a University of Illinois farmdoc webinar March 5.

Challenges

“Some of the challenges to prevention that we need to deal with include wildlife, the environment, fomite transfer and flock additions,” Ernst said.

Waterfowl is a major concern as a number of waterfowl species can serve as unaffected carriers.

“The control of migration of waterfowl is obviously an impossibility. We need to remember that migration occurs twice a year and at each end of that migration waterfowl from all of the flyways commingle, and that enables the virus to spread,” Ernst continued.

“Mortality in wild waterfowl is variable. Many species of ducks and geese can harbor the virus in a carrier state and these carrier birds can then pass the virus through their droppings and other secretions, thus contaminating the surfaces and making them ideal for further spread of the virus.”

The environment provides another challenge as the virus can survive different substrates for variable lengths of time.

“Much of this is dependent on temperature, pH and humidity. The point is that even though a surface may look clean, unless it’s been disinfected, it should be considered potentially contaminated,” Ernst said.

The virus can survive eight weeks at 39 degrees in wet or dry droppings, 30 days in feathers, one to 14 days in the soil, 26 hours on plastic, four and a half hours on skin, 24 to 48 hours on metal, and two weeks on wood.

Fomites are any inanimate objects that, when contaminated with or exposed to an infectious disease, can transfer the virus to a new host.

“Clothing and equipment that’s used for tasks other than specifically for the poultry operation are often sources for fomite transfer of the virus into the flock,” Ernst said.

“If you’ve got dirty boots, dirty coveralls, dirty equipment or equipment that’s been used other than with the flock, we run the risk of contamination and infection of the flock going forward.”

Adding birds to the flock also opens up a risk of infection.

“A lot of flocks aren’t managed as closed flocks, and that’s a risk for additional exposure. Adding new birds to an existing flock can be risky for a number of diseases, not just HPAI, and it’s especially true if the health status of the source flock is unknown,” Ernst noted.

Solutions

A solution to address the spread of HPAI from wildlife begins with sealing up entry points to help keep rodents and smaller birds from entering the buildings.

Keep the areas around buildings clean and free of loose feed will help deter birds from congregating.

“Additional rodent control may be needed as well for mice, rats and other rodents,” Ernst said. “Use waterfowl hazing strategies using devices such as propane cannons, Mylar tape, balloons and grid wiring over small ponds and other exclusion areas that can be useful to help keep waterfowl away from a facility.”

Preventing environmental or fomite transfer begins with good sanitation through continuous cleaning and disinfection of equipment, clothing and footwear to reduce potential flock infections.

Only people who are essential to the care of the flock and supporting operation should be entering the facility.

Employees should be discouraged from owning their own poultry. This is to help avoid the possibility of cross-contamination.

Vehicular traffic such as feed delivery employees, contractors and others should be restricted to designated areas, and disinfection of tires and the undercarriage of the vehicles needs to be completed on entry and exit from the flock.

Only dedicated equipment should be used in the facility, and it should be cleaned and disinfected often. The use of dedicated clothing and foot ware need to be an absolute requirement in the flock.

If flock additions are necessary, Ernst said the birds added should be from a single source, high health flock.

“The isolation of incoming birds is highly recommended when possible. If you can use an all-in/all-out practice that should be utilized with cleaning and disinfection of the facility being completed before restocking,” he said.

“Flock additions should be sourced from a flock that participates in a monitoring program for avian influenza. It’s highly recommended that birds be sourced from a National Poultry Improvement Plan member flocks that monitor for avian influenza.”

Online Resources

There are several online resources that block owners and producers can use to make their own flock plans and biosecurity plans and to learn more about the disease and methods to prevent HPAI from occurring in their flock.

USDA’s Defend the Flock Resource Center contains useful information on flock biosecurity and the development of a biosecurity plan that’s appropriately designed for individual flocks.

The Center for Food Security and Public Health at Iowa State University has developed a site containing information on the disease, biosecurity surveillance and other useful information about avian influenza.

The Secure Poultry Supply, housed at the University of Minnesota, contains useful information and instructions on poultry movements, especially during an avian influenza outbreak.

The National Poultry Improvement Plan site provides information on National Poultry Improvement Plan membership and the diseases of interest in the plan. Membership in this is voluntary, and members can choose which disease monitoring programs they want to participate in.