Controlling Avian Influenza: Prevention, Control and Remediation

By Keith Warriner, Ph.D. and Lara Jane Warriner, Department of Food Science, University of Guelph; Tatiana Koutchma, Ph.D., Agriculture Agri-food Canada; and Phyllis Posy, Posy Global

There has been an ongoing pandemic of avian influenza in North America for over three years. It has devastated the poultry industry and now is starting to impact the dairy and pet food sectors. Most consumers first were impacted by avian influenza as they witnessed the soaring price of eggs caused by the depopulation of chicken barns in a bid to prevent the spread of the virus. To date, over 150 million birds have been culled; despite this, the pandemic continues.

Know the Enemy

Viruses were the first form of life and have been the driving force of evolution. Every organism has a corresponding virus, explaining why they have become the most abundant lifeform (depending on the definition of life). Viruses are nanometers in size and were not visualized until the 1920s, although their devastating effects were observed much earlier. Specific to avian influenza, the first documentation was in 1878 and termed the fowl plague. 1 The name was not an overstatement, given that an outbreak of avian influenza is deadly, wiping out entire flocks within hours.

The virus shares similarities with that implicated in COVID-19 in that it is an enveloped virus that can undergo mutations to cross the species barrier. 2 There are two antigenic proteins on the surface of the virus, termed H and N, that are used for classification. In the Spanish Flu pandemic of 1918, H1N1, which was derived from avian influenza, caused over 50 million deaths globally. In more recent times, the H5N1 Influenza A subtype is of key concern. 1 H5N1 first was isolated in 1996 when it was linked to outbreaks in China and Hong Kong poultry houses. The virus jumped to humans, resulting in 18 cases and six deaths. The H5N1 spread through Africa, the Middle East and then to Europe during the 2000s. As the virus spread, it mutated to H5N6 and N5H8, which became prominent in Asia, Africa, Europe and the Middle East.

A new version of H5N1 emerged in wild birds in 2021, the first year it was detected in North America. 3 In 2022, the first reports of H5N1 affecting backyard and commercial poultry production were recorded and continue to spread over the years. Moreover, the H5N1 has crossed the species barrier to dairy cattle and humans. 4 The virus is hypervirulent in birds but less so in cattle; nevertheless, it has resulted in human cases. The greatest risk is for those who work with infected animals, with the eyes being the preferential entry point of infection in workers. 5 There have been scenarios where asymptomatic farm workers have transferred the influenza virus to their pets, with cats being especially susceptible.

How Does Avian Influenza Spread?

Avian influenza can exist in a hypervirulent or low pathogenic form, which can be interchangeable through mutation. 6 The low virulent form is of significant concern as it can infect hosts such as wild birds, which, with little or no symptoms, can spread the virus over large distances. If the virus then mutates to the hypervirulent form, it becomes deadly to birds and further mutation leads to the transfer to other species. The major concern is the further mutation of the avian influenza to produce another Spanish Flu-scale pandemic.

The most significant transmission route of H5N1 is by direct contact with infected animals and their secretions. From studies performed to date, the virus has greater stress tolerance compared to other Influenza A viruses and can survive up to 48 hours on surfaces. Survival is favored in low temperatures (4° C) and humidity conditions. 7 Given the tolerance, water, air and contact with contaminated surfaces have been identified as possible transmission routes. Foodborne routes are considered less significant, although there was a recall due to the detection of the virus in raw pet food. In addition, it has been shown that survival of the virus in eggs is up to four hours, but if internalized into the white or yolk, it can persist for up to 17 days. 8

Regarding poultry production facilities, the main concern is wild birds and infected animals entering barns. The virus readily can spread through secretions and survive over extended periods on surfaces, especially at low temperatures. 9 H5N1 also exhibits greater tolerance to UV-C, with a four-hour exposure of a manure filtrate to 4 µW/cm2 being insufficient to inactivate the virus. However, other reports suggest doses in the order of 10 mJ/cm2 are sufficient to inactivate surrogates (H5N2) when treated in phosphate buffer in the absence of organic matter. 10,11

Current Approaches to Avian Influenza Control

Control of avian influenza in poultry production first was introduced within the United States in 1924 and then passed into law in 2002 under the Animal Health Protection Act. The general approach has not changed significantly over the years, with seven principles being followed:

  1. Restricting visitors to poultry farms;
  2. Prohibiting farm workers from visiting other farms or owning birds or poultry;
  3. All-in-all-out flock management with birds being single-source supplied;
  4. Confinement within contained facilities with minimal contact with wild birds and animals;
  5. Rodent and insect control;
  6. Disinfection and waste disposal; and
  7. Ongoing monitoring of flocks.

Risk management

The detection of avian influenza within poultry production is very evident as the highly virulent virus causes high mortality rates. Other less obvious signs are a decrease in egg production, distressed birds, heavy breathing, disorientated birds and diarrhea. Birds infected with low pathogenic strains show no or milder symptoms but still are considered a risk due to the ability of the virus to mutate to a more virulent form. Encountering dead wild birds close to a poultry production facility provides further indicators the virus is within the area.

A typical response to detecting an outbreak is to create an exclusion zone (e.g., 10 km) around the point of the outbreak. Enhanced surveillance is performed within the zone, and increased restrictions are placed on movement from and between poultry facilities. In affected farms, restricted access to barns and personal protective equipment (PPE) – mask, overalls, gloves and boot covers – are required. Vehicles are sprayed with disinfectant, and disposable seat covers are applied. The depopulation of barns can be undertaken rapidly using carbon dioxide or foam-based approaches. The corpses of birds need to be disposed of to ensure containment of the virus – for example, inaccessible to wild animals and minimizing dissemination into soil, watersheds or air. Potential approaches include composting, burial, landfill, incineration and rendering. The method will depend on the number of birds and the resources (e.g., equipment, land) available.

Returning the barn to operations

Upon clearing the barns, there is a need to disinfect and quarantine for 21 days before considering re-population. The recommended sanitation regimes are to remove solid materials and then pressure wash with water to remove debris. The sanitizer should be applied on all surfaces for 30 minutes before rinsing. The sanitation cycle is repeated seven days after and repeated 24 hours later (secondary disinfection). In addition to barns, the cages, waterlines and duct systems within the barn environment must be sanitized. Those entering the barn need to go through footbaths, and PPE needs to be sanitized. The sanitizers applied are sulphur dioxide, peroxyacetic acid, formaldehyde, Quaternary Ammonium Salt and polyphosphate. Fogging the environment with chlorine dioxide, formaldehyde or peracetic acid vapor also can be applied. Typical verification steps to evaluate the sanitary status of the barn are through visual inspection in combination with adenosine triphosphate (ATP) readings.

The Application of Ultraviolet Light in Controlling Avian Influenza

The history of pandemics has shown that people tend to rely on dated control measures when it comes to infection control. In hindsight, the risk management practices should have evolved the same as the virus by taking advantage in advances in technology, such as ultraviolet light (UV). Through the adoption of existing technologies and the development of new technologies, it can be envisaged that UV can contribute toward prevention, risk management and remediation.

Prevention

Avian influenza is transferred directly and indirectly via secretions, especially within aerosols. Therefore, high-risk areas would be air, water and surfaces. Air and water disinfection systems based on UV are commercially available and can be readily adopted. More challenging is the disinfection of vehicles, boots, crates and tools. The main issues would be the need to illuminate shaded areas, remove organic matter without spreading the virus and operate within occupied environments.

This could be addressed by using contained areas to place objects within a chamber, similar to a car wash, but with UV to prevent aerosols from escaping. There also is the option of using Far-UV, which has proven disinfection power through commercial application rather than systematic laboratory studies. The application of UV-based technologies, such as the hydroxyl-radical process that utilizes the photo-Fenton reactions, would overcome shading issues.

Risk Management

If avian influenza is detected within a poultry or other animal production facility or local area, there is a need to contain the virus and prevent dissemination to other areas. The same prevention controls would be followed, with additional controls to minimize exposure to workers. For example, PPE will be extensively used, and methods for disinfection for re-use or prior to disposal will be required. This could be extended to ensuring any waste leaving the facility also undergoes treatment that could include wastewater treatment technologies.

Remediation

Repopulating barns after an outbreak is one of the most time-consuming procedures, and it can take months to complete. The main limiting factor is how to disinfect large areas consistently. UV technologies already have been developed to facilitate disinfection in large areas, especially if coupled with photo-active antimicrobial coatings. 12 UV-based systems, such as the hydroxyl-radical process, can be applied to overcome issues of shading 13 and potentially decrease the 21-day hold time required following an infection event. UV-C combined with ozone is a further promising approach for the inactivation of avian influenza on surfaces. 14

Final Thoughts

Avian influenza outbreaks have occurred throughout history but now have a more significant impact given the size of animal production systems and the ease with which the virus spreads between densely populated environments. The ability to detect and study avian influenza has contributed to taking preventative measures and corrective actions more so than previously. To avoid the next global pandemic, there is a need to adopt a more preventative approach and to modernize disease response action plans.

Ultraviolet-based technologies are not a silver bullet but can supplement or replace current sanitation approaches. The benefits of UV are an effective chemical-free approach to which viruses, such as avian influenza, are highly susceptible. Many of the technologies currently exist for the disinfection of air, water and surfaces but need a change of mindset by regulators and industry to battle against the next pandemic.

This recurring column tracks topics of interest to Food and Beverage safety as they relate to UV technologies.

Research needs

Establish the UV-mediated inactivation kinetics of avian influenza.

Develop cost-effective methods to inactivate avian influenza in aerosols.

Engineer systems to decontaminate vehicles, barns and other areas.

Identify surrogates to H5N1 (for example, N1H1, bacteriophages pHi6) that can be applied within and outside the laboratory environment.

Identify regulatory routes and requirements to implement UV-technologies in poultry production and related areas.

Resources

United Nations Food and Agriculture Organization, The spread of H5N1 highly pathogenic avian influenza calls for stepped up action, FAO says, https://www.fao.org/newsroom/en

United States Department of Agriculture, https://www.aphis.usda.gov/livestock-poultry-disease/avian/avian-influenza/hpai-detections/livestock/enhance-biosecurity

United Kingdom Human Animal Infections and Risk Surveillance, https://www.gov.uk/government/publications/hairs-risk-statement-avian-influenza-ah5n1-in-livestock/hairs-risk-statement-avian-influenza-ah5n1-in-livestock

European Food Standards Agency, “Coordinated One Health investigation and management of outbreaks in humans and animals,” https://www.efsa.europa.eu/en/efsajournal/pub/9183

References

  1. Lupiani, B., & Reddy, S. M. (2009). The history of avian influenza. In Comparative Immunology, Microbiology and Infectious Diseases (Vol. 32, pp. 311–323). https://doi.org/10.1016/j.cimid.2008.01.004.
  2. Proenca-Modena, J. L., Macedo, I. S., & Arruda, E. (2007). H5N1 avian influenza virus:: An overview. BRAZILIAN JOURNAL OF INFECTIOUS DISEASES, 11(1), 125–133. https://doi.org/10.1590/S1413-86702007000100027.
  3. Roberts Jr., N. J., & Krilov, L. R. (2022). The Continued Threat of Influenza A Viruses. VIRUSES-BASEL, 14(5). https://doi.org/10.3390/v14050883.
  4. Zanin, M., Le, T. B., Na, W., Kang, J.-A., Kwon, H.-J., Hwang, J., Ga, E. H., Wong Sook-San and Cho, H.-J., Song, D., Kim, H. K., & Jeong Dae Gwin and Yoon, S.-W. (2023). Potential for transmission of naturally mutated H10N1 avian influenza virus to mammalian hosts and causing severe pulmonary disease. FRONTIERS IN MICROBIOLOGY, 14. https://doi.org/10.3389/fmicb.2023.1256090.
  5. Shittu, I., Silva, D., Oguzie, J. U., Marushchak, L., Olinger, G. G., Lednicky, J. A., Trujillo-Vargas, C. M., Schneider, N. E., Hao, H. P., & Gray, G. C. (2025). A One Health Investigation into H5N1 Avian Influenza Virus Epizootics on Two Dairy Farms. CLINICAL INFECTIOUS DISEASES, 80(2), 331–338. https://doi.org/10.1093/cid/ciae576.
  6. Aldhaeefi, M., Rungkitwattanakul, D., Saltani Ilyas and Muirhead, A., Ruehman, A. J., Hawkins, W. A., & Daftary, M. N. (2024). Update and narrative review of avian influenza (H5N1) infection in adult patients. PHARMACOTHERAPY, 44(11), 870–879. https://doi.org/10.1002/phar.4621.
  7. Domanska-Blicharz, K., Minta, Z., Smietanka Krzysztof and Marche, S., & van den Berg, T. (2010). H5N1 High Pathogenicity Avian Influenza Virus Survival in Different Types of Water. AVIAN DISEASES, 54(1, S), 734–737. https://doi.org/10.1637/8786-040109-ResNote.1.
  8. Thomas, C., & Swayne, D. E. (2009). Thermal Inactivation of H5N2 High-Pathogenicity Avian Influenza Virus in Dried Egg White with 7.5% Moisture. In Journal of Food Protection (Vol. 72, Issue 9).
  9. Shahid, M. A., Abubakar, M., Hameed, S., & Hassan, S. (2009). Avian influenza virus (H5N1); effects of physico-chemical factors on its survival. VIROLOGY JOURNAL, 6. https://doi.org/10.1186/1743-422X-6-38.
  10. Lucio-Forster, A., Bowman, D. D., Lucio-Martinez, B., Labare, M. P., & Butkus, M. A. (2006). Inactivation of the avian influenza virus (H5N2) in typical domestic wastewater and drinking water treatment systems. ENVIRONMENTAL ENGINEERING SCIENCE, 23(6), 897–903. https://doi.org/10.1089/ees.2006.23.897.
  11. McDevitt, J. J., Rudnick, S. N., & Radonovich, L. J. (2012). Aerosol susceptibility of influenza virus to UV-C light. Applied and Environmental Microbiology, 78(6), 1666–1669. https://doi.org/10.1128/AEM.06960-11.
  12. Hasegawa, T., Tamura, M., Satoh, K., Tsujimura, M., Kawamura, A., Thammakarn, C., Hakim, H., Ruenphet, S., & Takehara, K. (2013). Inactivation of Goose Parvovirus, Avian Influenza Virus and Phage by Photocatalyst on Polyethylen Terephthalate Film under Light Emitting Diode (LED). JOURNAL OF VETERINARY MEDICAL SCIENCE, 75(8), 1091–1093. https://doi.org/10.1292/jvms.13-0020.
  13. Hasani, M., Campbell, T., Wu, F., & Warriner, K. (2021). Decontamination of N95 and surgical masks using a treatment based on a continuous gas phase-Advanced Oxidation Process. PLoS ONE, 16(3 March). https://doi.org/10.1371/journal.pone.0248487.
  14. Sobhy, N. M., Muñoz, A. Q., Youssef, C. R. B., & Goyal, S. M. (2023). Inactivation of Three Subtypes of Influenza A Virus by a Commercial Device Using Ultraviolet Light and Ozone. AVIAN DISEASES, 67(4), 305–309.

RELATED ARTICLESMORE FROM AUTHOR