Since October 2020, the world has experienced an unprecedented outbreak of highly pathogenic avian influenza, with the frequency and scale of outbreaks reaching unprecedented levels. In 2025, avian influenza has undergone frequent mutations, infecting a wide range of host species and exhibiting complex transmission chains, posing significant challenges to its prevention and control in China. Waterfowl are the primary hosts of the H5 subtype avian influenza virus. In recent years, H5 subtype avian influenza in waterfowl has posed high risks of outbreaks and substantial economic losses. Therefore, the author proposes several recommendations for the prevention and control of avian influenza in waterfowl farms, aiming to assist waterfowl farming operations.

Develop a scientific immunization schedule and use suitable vaccines for vaccination.

Select vaccines containing locally prevalent strains for immunization. In densely populated waterfowl farming areas and high-risk regions, it is recommended to increase the frequency of vaccination. For meat birds marketed after 60 days of age, two doses of H5+H7 vaccine are recommended.

For layer/breeder birds:

Before laying: At least 3 vaccinations (recommended at 7 days, 21 days, and 4 weeks before laying).

During laying: Monitor antibody levels every 2-3 months. If the titer falls below log?8, revaccinate immediately.

Risk Management During the Immunization Gap Period

Waterfowl face the highest risk of disease within the first 30 days of life, particularly during the immunization gap period (within 15 days after the first vaccination), which is characterized by high incidence rates and significant mortality.  

Prevention and Control Recommendations:  

1. Strict Environmental Disinfection:  

  Disinfect the environment 1-2 times daily to reduce pathogen load.  

2. Isolation of Young Birds:  

  Keep chicks under 30 days of age isolated to prevent contact with wild birds and contaminants.  

3. Timely Initial Vaccination:  

  Ensure the first vaccination is administered no later than 10 days of age to shorten the immunization gap period.  

4. Health Support with Medications:  

  Use supportive medications to enhance disease resistance in the flock.

Evaluation of Immunization Effectiveness

Antibody monitoring is one of the most effective methods for assessing vaccine efficacy. For waterfowl, it is recommended to conduct antibody testing 3-4 weeks post-vaccination. Due to the relatively weaker immune response in waterfowl, antibody levels at 4 weeks are generally better than those at 3 weeks.  

Key Considerations:  

1. Sampling Rate:  

  Ensure a sampling rate of ≥1% (with a minimum of 20 birds per house).  

2. Antibody Titer Testing:  

  Test for antibody titers against H5 subtype variant strains (the required titer for meat birds is ≥log??).  

3. Revaccination for Non-Compliant Groups:  

  If antibody levels do not meet the standard, revaccination is recommended within 7 days, followed by retesting.

Enhancing Biosecurity Management

I. Wild Bird Control  

1. Install bird nets (mesh size ≤ 2 cm) and bird deterrent devices (e.g., sonic or reflective equipment).  

2. Clear weeds and manage water sources in surrounding areas to reduce wild bird habitats.  

II. Water Source Management  

1. Regularly disinfect fish ponds/water reservoirs (using quicklime or chlorine dioxide once weekly).  

III. Farm Zoning and Isolation  

1. Implement closed management practices, ensuring strict disinfection of personnel and vehicles entering the farm.  

2. Install fencing in free-range systems and separate birds of different age groups into distinct zones.  

Focus on Controlling Immunosuppressive Diseases

Circoviruses, flaviviruses, reoviruses, parvoviruses, adenoviruses, and mycotoxins can all cause immunosuppression in waterfowl, leading to vaccine failure. Therefore, in addition to administering high-quality avian influenza vaccines, it is crucial to prevent and control common immunosuppressive diseases.  

To ensure healthy growth and reduce disease risks in waterfowl, it is essential to:  

- Eliminate immunosuppressive diseases in breeder flocks,  

- Provide high-quality chicks,  

- Strengthen balanced nutrition,  

- Maintain optimal rearing environments.