Highly Pathogenic Avian Influenza

Highly Pathogenic Avian Influenza (HPAI) presents a worldwide challenge to the poultry industry due to its extensive spread and high death rates. The transformation of low-pathogenic avian influenza (LPAI) viruses into HPAI forms has been an important aspect of their evolutionary history, greatly impacting avian populations worldwide (Lee, Criado, & Swayne, 2020). Particularly virulent strains of avian flu, such as H5N1, have been responsible for major bird epidemics (Charostad, 2023). The article discusses HPAI epidemiological status and evidence-based strategies for its prevention and control.

Clinical signs of HPAI in birds can include respiratory distress, nasal discharge, coughing, sneezing, diarrhea, reduced egg production, and high mortality rates (USDA, 2022). HPAI is extremely contagious and deadly to domestic poultry, resulting in up to 100% mortality. Because of its high pathogenicity, early detection is vital to prevent the spread of HPAI.  Upon identification of HPAI, it is imperative to swiftly implement biosecurity measures, including culling of infected and exposed birds, strict quarantine and movement controls, and rigorous disinfection protocols, to halt the spread of the virus and safeguard the nation's poultry flocks and economy.

HPAI Recent Updates
The spread of HPAI in 2023 continues to affect global bird populations, primarily domestic birds such as chickens, turkeys, ducks, and geese. HPAI varies in its impact on domestic waterfowl and wild birds, with some birds being asymptomatic despite infection. Transmission occurs through direct contact with infected birds or indirectly via contaminated surfaces (USDA, 2022). The intercontinental movement and reassortment of these viruses have been a critical factor in their global spread (Bessière et al., 2021). 

The latest update from the U.S. Department of Agriculture (USDA) on February 1st, reported 202 confirmed HPAI cases over the past 3 months, affecting 114 commercial poultry flocks and 88 backyard flocks, totaling approximately 21.57 million birds. The 114 commercial poultry flocks include turkeys, ducks, table egg layers, and broilers located throughout the US. USDA emphasizes surveillance and strong biosecurity practices, particularly during migratory seasons, to detect and manage the virus (USDA, 2022a).

HPAI Control
Controlling the spread of HPAI involves stringent biosecurity measures and active surveillance. Movement restrictions and increased surveillance in poultry systems have been effective in controlling the spread (Di Pillo et al., 2020). In the event of an HPAI outbreak, immediate action is crucial. Upon detection, the USDA and State authorities initiate testing and diagnosis, often providing same-day results. If HPAI is confirmed, a quarantine is imposed, restricting movement and requiring strict biosecurity measures. Cooperation with authorities is essential for effective containment. The response includes depopulation of affected birds, with USDA compensation, and thorough cleaning and disinfection of the housing system. Epidemiological investigations trace the infection's origin and spread. Once the virus is eliminated and confirmed by the USDA, normal operations can resume (USDA, 2022). Prompt action and following the guidelines are key to controlling HPAI and protecting poultry. The recent outbreaks emphasize the importance of rapid response and strict containment measures led by authorities. Effective control of HPAI is imperative not just for avian health but also for safeguarding public health and the global poultry industry.


Bessière, P., Figueroa, T., Coggon, A., Foret-Lucas, C., Houffschmitt, A., Fusade-Boyer, M., Dupré, G., Guérin, J., Delverdier, M., & Volmer, R. (2021). Opposite outcomes of the within-host competition between high- and low-pathogenic H5N8 avian influenza viruses in chickens compared to ducks. Journal of Virology, 96. 

Charostad, J., Zadeh Rukerd, M. R., Mahmoudvand, S., Bashash, D., Hashemi, S. M. A., Nakhaie, M., & Zandi, K. (2023). A comprehensive review of highly pathogenic avian influenza (HPAI) H5N1: An imminent threat at doorstep. Travel Medicine and Infectious Disease, 55, 102638.

Di Pillo, F., Jimenez-Bluhm, P., Baumberger, C., Marambio, V., Galdames, P., Monti, G., Schultz-Cherry, S., & Hamilton-West, C. (2020). Movement restriction and increased surveillance as efficient measures to control the spread of highly pathogenic avian influenza in backyard productive systems in Central Chile. Frontiers in Veterinary Science, 7, Article 424. 

Lee, D. H., Criado, M. F., & Swayne, D. E. (2021). Pathobiological origins and evolutionary history of highly pathogenic avian influenza viruses. Cold Spring Harbor Perspectives in Medicine, 11(2), a038679. 

Rcheulishvili, N., Papukashvili, D., Liu, C., Ji, Y., He, Y., & Wang, P. (2022). Promising strategy for developing mRNA-based universal influenza virus vaccine for human population, poultry, and pigs – focus on the bigger picture. Frontiers in Immunology, 13, 1025884.

USDA-APHIS. (2022a). 2022 HPAI in commercial and backyard flocks. Available at: https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/avian-influenza/hpai-2022/2022-hpai-commercial-backyard-flocks.

USDA-APHIS. (2022). Protect your poultry from avian influenza. Available at: https://www.aphis.usda.gov/publications/animal_health/bro-protect-poultry-from-ai.pdf.

Published on

19 February 2024


  • Poultry

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