Highly Pathogenic Avian Influenza H5N1: A Continued Concern for Poultry Producers

Barry Whitworth, DVM, MPH
Senior Extension Specialist

Department of Animal & Food Sciences

Freguson College of Agriculture

Oklahoma State University

Highly Pathogenic Avian Influenza (HPAI) H5N1 continues to be a concern for backyard and commercial poultry producers. The disease has resulted in flock losses, reduced income, and trade restrictions. In September alone, eleven commercial flocks in Minnesota, North Dakota, and South Dakota were infected, along with several backyard flocks in multiple states. Since the start of the current HPAI outbreak on February 8, 2022, more than 175 million domestic birds have been lost. This total includes both commercial and backyard flocks. In addition, many wild birds have also died. Mammals have not fared any better, with numerous wild and domestic animals succumbing to the virus. As wild birds begin their southern migration, Oklahoma poultry producers need to be especially vigilant in protecting their flocks.

Avian influenza (AI) is a highly contagious viral disease. While there are many subtypes of the virus, H5N1 is classified as highly pathogenic, meaning it spreads rapidly and often causes severe illness and high mortality in chickens, turkeys, and other poultry. Wild waterfowl are natural reservoirs of the virus and can shed it without showing signs of illness, making them an ongoing threat to domestic flocks.

Clinical signs of HPAI often appear suddenly and may include:

• Sudden death with no prior symptoms
• Respiratory problems such as coughing, sneezing, watery eyes, and nasal discharge
• Decreased water and feed consumption
• Drop in egg production and/or misshapen eggs
• Swelling of the comb, wattles, head, eyelids, or hocks
• Nervous system disorders, including tremors, incoordination, and abnormal head positions

The H5N1 virus spreads through direct contact with infected birds (domestic or wild), as well as contaminated equipment, feed, water, and clothing. The virus can also travel short distances on dust particles or feathers. The risk of transmission increases during wild bird migration.

Since the United States (U.S.) has no approved treatment or vaccine for HPAI, the best defense is a strong biosecurity program. Biosecurity involves management practices designed to reduce or prevent unwanted threats from entering a flock. Key protocols include limiting traffic, keeping facilities clean, and monitoring for disease.

The first line of defense is to limit traffic on and around poultry facilities. Visitors and vehicles should not enter unless absolutely necessary. If someone must enter, they should wear clean coveralls and disposable shoe covers and wash their hands before and after visiting. All visitors should dip their shoes in a disinfectant solution upon entering and exiting. No other animals, wild or domestic, should be allowed into poultry facilities.

Sanitation is a critical part of any biosecurity plan. All equipment, feeders, waterers, and buildings should be cleaned and disinfected regularly. First, remove all fecal material and dirt. Then apply disinfectants, allowing enough contact time for them to be effective. Foot baths must be properly maintained. The property surrounding poultry houses should be mowed and kept clean. Failure to cut grass or promptly clean spilled feed can attract wild birds and animals, which have been linked to the spread of HPAI.

Birds should be monitored daily. Dead birds should be collected and disposed of promptly. Producers should be familiar with the clinical signs of HPAI. Any unusual increase in sick or dead birds should be reported immediately to the proper authorities. Poultry producers can contact their veterinarian, their Oklahoma State University County Extension office, the Oklahoma State Veterinarian at 405-522-6141, or the USDA toll-free hotline at 1-866-536-7593. Prompt reporting helps limit the spread of the disease.

Avian influenza remains a major threat to the U.S. and Oklahoma poultry industries. It is the responsibility of all commercial and backyard poultry producers to take every possible step to protect their flocks and safeguard this vital industry. For more information about HPAI, poultry producers should contact their veterinarian or their local Oklahoma State University Agricultural Extension Educator. Additional information is available at the USDA H5N1 Influenza website at https://www.aphis.usda.gov/h5n1-hpai. 

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.