Recent Developments in Avian Influenza: Modern Strategies for Control and Eradication
A Brief Summary of the Latest Developments
Professor Dr. Diaa Mohammed Taher Jawhar, Professor of Public Health, University of Mosul
2/ 11/ 2025
Continued Global Spread:
Highly pathogenic avian influenza (HPAI) strains, particularly the H5N1 and H5Nx subtypes, continue to circulate widely in wild birds and poultry. Unprecedented infections have also been reported in mammalian species (including dairy cows in the United States). This wide range of hosts increases the likelihood of viral mutation.
Human Infection: Human infections remain rare but possible. Dozens of isolated cases were reported in 2024–2025, mostly due to direct occupational exposure. No evidence of sustained human-to-human transmission has been recorded.
Genomic Surveillance: Real-time genomic sequencing (such as Nextstrain and GISAID platforms) has become a crucial tool for monitoring genetic changes, identifying dangerous mutations, and updating avian vaccines.
One Health Strategy: The FAO, WOAH and WHO have launched a joint plan to coordinate efforts in surveillance, diagnosis, vaccination when needed and community outreach to reduce risks.
Key Strategies for Disease Control
1. Integrated Surveillance of Wildlife, Birds, Poultry, and Humans
Surveillance programs should be maintained in wild birds, commercial flocks, and high-risk environments (such as wastewater and mixed farms), linking field diagnosis with genomic analysis to rapidly identify emerging strains.
2. Enhanced Biosecurity on Farms and in Markets
Measures include: restricting access to farms, disinfecting equipment and vehicles, isolating poultry from wild birds, and housing them in enclosed spaces during seasonal periods of risk. Temporarily closing and cleaning live bird markets is also recommended when the virus is detected.
3. Targeted Vaccination Programs (When Needed)
Vaccination is a supportive tool for reducing infections and economic losses in affected areas, with the following precautions:
• Use vaccines that are matched to the locally circulating strains. This means that avian influenza viruses (especially strains like H5 and H7) are constantly changing through genetic mutation and reassortment. Therefore, a vaccine developed some time ago may not be effective against new strains circulating in the region.
The goal of using vaccines that match local strains is to achieve effective immunity in poultry against the virus already circulating in the environment, prevent asymptomatic infections that could persist in the flock despite vaccination, and limit the spread of the disease to other farms or even to humans (in some species). This is done practically by local veterinary laboratories isolating the virus currently circulating in the field, analyzing its genetic and antigenic characteristics, and comparing these characteristics with available vaccine strains. If there are significant differences, the vaccine is updated or a new vaccine is developed that matches the local strain.
• Applying the DIVA strategy (Differentiating Infected from Vaccinated Animals).
Yes, the DIVA strategy (Differentiating Infected from Vaccinated Animals), or differentiating infected from vaccinated birds, is a cornerstone of avian influenza control programs when vaccines are used. The basic idea is that when birds are vaccinated, their bodies develop antibodies to the virus (due to the vaccine). This makes it difficult to determine whether the birds are protected by the vaccine or have actually been infected with the field virus. The DIVA strategy enables us to differentiate between the two cases by using a modified vaccine, where:
The vaccine contains specific antigens from the virus (e.g., only the H protein), while other antigens present in the natural virus are excluded or altered (e.g., the N protein or part of an internal protein).
Therefore, when we perform serological tests:
– If the birds have antibodies only against the vaccine antigens, they are vaccinated and not infected.
If antibodies are found against antigens not present in the vaccine, the birds are actually infected with the field virus.
DIVA implementation tools include: using vaccines containing only one antigen (such as H5), conducting an ELISA test for the N1 or N2 protein to detect natural infection, and establishing a serological surveillance system to track the actual spread of the virus on farms.
The benefits of the DIVA strategy include allowing for continued vaccination without losing epidemiological surveillance capabilities, helping to differentiate between disease outbreaks and vaccine-associated infections, and supporting international export plans, as importing countries require confirmation that the birds are free of actual infection and a phased exit plan to prevent the virus from persisting asymptomatically.
4. Humane Culling of Infected and Contact Flocks
The rapid removal of infected birds, coupled with the implementation of a tracking system and fair compensation for farmers, remains one of the most effective means of halting local spread, provided that carcasses are disposed of safely and the area is thoroughly disinfected.
5. Coordination According to the “One Health” Approach and Protection of Workers
This requires integrating the efforts of veterinary, health, and environmental authorities in monitoring and response, ensuring that workers exposed to the virus are provided with personal protective equipment, medical follow-up, and prophylactic antiviral medications.
6. Continuous Genomic Surveillance to Guide Actions
Genetic sequencing analysis helps in updating vaccines, monitoring mutations associated with adaptation to mammals or drug resistance, and guiding preventive measures when needed.
7. Movement and Trade Regulations and Compensation Programs
Temporary restrictions on poultry movement and trade, along with fair compensation for farmers, are essential to ensure rapid reporting and cooperation in containing the virus.
8. Communication and Community Engagement
Ongoing awareness campaigns for poultry farmers, smallholders, and market workers are essential to reducing risky practices and encouraging early case reporting.
Towards Eradication: What is Realistically Possible?
Global eradication of avian influenza is not possible while the virus persists in wild birds. However, localized eradication in specific areas is possible through early detection, rapid isolation, targeted vaccination, and improved biosecurity.
The realistic goal is sustainable control and risk reduction through strengthening health and agricultural systems within the framework of One Health for the period 2024–2033.
Operational Recommendations for Countries and Farms
1. Expand gene sequencing programs and share data immediately.
2. Strengthen biosecurity, especially on mixed farms (poultry/cattle).
3. Maintain a stockpile of vaccines that match circulating strains and implement DIVA testing.
4. Ensure worker safety through training, protective equipment, and health monitoring programs.
5. Establish effective compensation systems to encourage early reporting and rapid response.
Key Findings
Highly pathogenic avian influenza remains a recurring threat requiring constant vigilance due to the expanding range of hosts and frequent mutations. The best results are achieved through an integrated response combining genetic analysis, targeted vaccination, biosecurity, rapid culling, worker protection, and transparent international cooperation.
Sources:
– World Health Organization (WHO): Updates on Avian Influenza Vaccines and Activities
– Food and Agriculture Organization (FAO): Global Reports on Avian Influenza with Human Transmission Potential
– Nextstrain Real-Time Virus Evolution Tracking Platform
– Joint Assessment (FAO/WOAH/WHO) July 2025. – Centers for Disease Control and Prevention (CDC): Monthly Summaries of Human H5N1 Cases (2024–2025).
