Avian Influenza Update

Barry Whitworth, DVM

Area Food/Animal Quality and Health

Specialist for Eastern Oklahoma

High Path Avian Influenza (HPAI) continues to be a problem in commercial and backyard poultry in the Unites States (US) with over 60 million birds affected. Since the start of the outbreak in 2022, 879 flocks (347 commercial and 532 backyard flocks) have been confirmed with HPAI in the US. Many wild birds and mammals have been affected as well. Five backyard flocks and one commercial flock have been confirmed with HPAI during this outbreak in Oklahoma. The latest was detected in a backyard flock in Carter County on October 16, 2023. For a complete listing of domestic birds, wild birds, and mammals affected by HPAI visit 2022-2023 Detection of High Path Avian Influenza website at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/avian-influenza/2022-hpai.

Avian influenza (AI) is a highly contagious viral disease. The virus is classified as either Low Path Avian Influenza (LPAI) or HPAI depending on the virulence. This virus infects many food producing birds such as chickens and turkeys while it commonly resides in migratory waterfowl and many other wild birds. Most often ducks, geese, and wild birds harbor the virus in the intestinal tract without having any clinical signs of the disease. The virus is shed in the feces and respiratory secretions from infected birds. Poultry can be infected with the virus when they come in direct contact with infected birds or consume feed that is contaminated with the virus. The virus can be spread indirectly through objects like shoes, clothes, or equipment contaminated with the virus.

Clinical signs of the disease vary depending on the severity of the virus and the organ system affected. LPAI usually results in no clinical signs or only mild problems. However, HPAI has many different clinical signs. Death with no symptoms is a common finding. Respiratory problems such as coughing, sneezing, watery eyes, and nasal discharges may be seen. Depression resulting in loss of appetite and decrease consumption of water may occur. Egg production may be impacted with a decrease in production and/or softshell or misshapen eggs. A bird’s comb, wattle, head, eyelids, and hocks may swell. Combs and wattles may turn purple. Nervous system disorders including tremors, incoordination, and unusual positions of the head may be seen. Diarrhea has been reported in some cases. For more information about clinical signs visit Defend the Flock-Signs of Illness at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/defend-the-flock-program/outbreak-illness/outbreak-illness.

For commercial and backyard poultry flocks, the best defense against HPAI is a sound biosecurity program. Biosecurity is the development and implementation of management procedures intended to reduce or prevent unwanted threats from entering a flock. The protocol is designed to reduce or prevent the spread of unwanted threats through the flock and eliminate any unwanted pathogens that may enter the flock. Lastly, a biosecurity plan is designed to prevent threats from infecting neighboring poultry operations. Biosecurity can be broken down into four basic areas which include traffic, isolation, sanitation, and husbandry.

The first line of defense should be limiting the traffic that enters the area. Poultry operations should have a perimeter buffer area (PBA). For backyard poultry operations, this could be a fence. In commercial operations this may be a fence or road that surrounds the facility. All entry points need to be clearly marked with “Do Not Enter” signs. In a study by United States Department of Agriculture (USDA) evaluating factors associated with introduction of HPAI in layer farms in the US, the presence of a gate was found to be protective against the introduction of the virus. Gates with signage may encourage people to follow biosecurity protocols.

Inside the PBA, a line of separation (LOS) needs to be established. The LOS isolates the birds from possible sources of infections. The LOS is usually the walls of the poultry building plus the entry point.  No person should cross this line without following proper biosecurity protocols. Producers should provide visitors with clean coveralls and disposable shoe covers. Visitors should wash their hands before and after visiting the facility. All visitors should dip their shoes in a disinfectant solution when entering and exiting the facility. Also, no other animals, wild or domestic should cross the LOS.

Sanitation is one of the most important parts of a biosecurity plan. All equipment, feeders, waterers, and buildings need to be cleaned and disinfected regularly. First, all fecal material and dirt should be physically removed. Next, disinfectants must be applied and allowed sufficient contact time to work properly. Foot baths need to be properly maintained. The property outside the poultry house should be kept mowed and cleaned. Failure to keep the grass cut and/or to promptly clean up feed spills is associated with HPAI.

Poultry producers must also practice good animal husbandry. Flocks need to be observed several times per day. Producers need to collect and dispose of dead birds frequently. Producer should know the clinical signs of a sick bird. Any unusual increases in sick or dead birds should be reported to proper authorities. Backyard producers have several options. They can contact their veterinarian or Oklahoma State University County Extension office. They can also contact the Oklahoma State Veterinarian at 405-522-6141.

The National Poultry Improvement Plan (NPIP) has guidelines for a biosecurity protocol. Commercial and backyard poultry producers should examine the NPIP 14 standards of the biosecurity protocol. Any areas that do not meet the standards need to be addressed. The NPIP biosecurity audit form can be found at http://www.poultryimprovement.org/documents/AuditForm-2018BiosecurityPrinciples.pdf. Additional sources for backyard poultry producers can be found at the USDA Defend the Flock website at healthybirds.aphis.usda.gov, Protect Your Poultry From Avian Influenza at  https://www.aphis.usda.gov/publications/animal_health/bro-protect-poultry-from-ai.pdf or Oklahoma State University fact sheet Small Flock Biosecurity for Prevention of Avian Influenza ANSI-8301.

Avian Influenza is a major threat to the US and Oklahoma poultry industry. It is the responsibility of all commercial and backyard poultry producers to do everything in their power to protect this industry.

Reference 

Swayne, D.E. and Halvorson, D.A. 2003 Influenza. In Y. M. Saif (ed.). Diseases of Poultry, 11^th ed. Iowa State Press: Ames, Iowa, 135-160.

Green, A. L., Branan, M., Fields, V. L., Patyk, K., Kolar, S. K., Beam, A., Marshall, K., McGuigan, R., Vuolo, M., Freifeld, A., Torchetti, M. K., Lantz, K., & Delgado, A. H. (2023). Investigation of risk factors for introduction of highly pathogenic avian influenza H5N1 virus onto table egg farms in the United States,

2022: a case-control study. Frontiers in veterinary science, 10, 1229008.