Farm Alert highlights a critical development in global animal health surveillance following the release of new guidelines by the Food and Agriculture Organization of the United Nations (FAO). These recommendations aim to guide countries in implementing effective monitoring systems for early detection of influenza infections in cattle and other mammals, marking a proactive step in managing zoonotic risks and safeguarding public health.

The highly pathogenic avian influenza (HPAI) H5N1 virus has exhibited significant adaptability since its emergence over two decades ago. Clade 2.3.4.4b, identified in 2021, has expanded its host range to include wild birds, poultry, and terrestrial and marine mammals such as tigers, seals, and domestic pets. Alarmingly, 2024 has seen confirmed detections of the virus in dairy cattle, accompanied by cases of farm workers exposed to infected animals. These findings emphasize the necessity for robust surveillance systems.

Addressing a Growing Threat

In its publication Recommendations for the Surveillance of Influenza A(H5N1) in Cattle – with Broader Application to Other Farmed Mammals, FAO outlines critical strategies for early detection and response. Given the potential for spillover events from birds to cattle and humans, the guidelines encourage countries to adopt a surveillance framework focused on high-risk areas. Such areas include regions with dense poultry or dairy cattle populations and sites frequented by migratory birds.

FAO emphasizes the importance of utilizing both formal and informal surveillance sources, including farmer reports, social media trends, and market price fluctuations. These approaches aim to strengthen passive surveillance systems, ensuring that suspected cases are promptly identified and reported.

Clinical Signs and Surveillance Challenges

Clinical signs observed in affected cattle include decreased milk production, fever, lethargy, thickened colostrum-like milk, and dehydration. However, the infection may present without symptoms in some animals, complicating detection efforts. Transmission appears to be influenced by the movement of infected cattle, shared equipment, and interactions between infected dairy farms and nearby poultry units.

Pigs are also a concern, given their potential to facilitate genetic reassortment between avian and human influenza viruses, raising the risk of new pandemic strains.

Guidance for Surveillance and Response

FAO recommends that all countries establish systems to rapidly detect HPAI H5N1 spillover from birds to non-avian species, including cattle. The minimum surveillance objectives should include:

• Encouraging self-reporting by farmers.
• Conducting opportunistic testing during vaccination campaigns.
• Implementing risk-based sampling strategies based on geographic and seasonal factors.

If HPAI H5N1 is confirmed in cattle, public health authorities must be notified immediately. Investigations should assess potential exposure among farm workers and others in close contact.

Global Reporting and Collaboration

FAO underscores the importance of sharing data through platforms like the World Animal Health Information System (WAHIS) and its Global Animal Disease Information System (EMPRES-i+). This collaborative effort is vital for tracking the disease and implementing evidence-based control measures.

For more details, visit the FAO website.