Role of migratory birds in the spread of avian influenza amongst bird populations in the European Union

Apr 18 2006

European Food Safety Authority - EFSA has published a scientific statement on the role of migratory birds in the spread of avian influenza amongst bird populations in the European Union.

The Panel on Animal Health and Welfare (AHAW) of the European Food Safety Authority (EFSA) has adopted a scientific statement on the role of migratory birds in the spread of the H5N1 form of avian influenza (AI) amongst domestic and wild bird populations in the European Union (EU). The scientific statement confirms that some species of wild birds are carrying the disease, lists those birds most likely to expose domestic poultry to H5N1 and identifies free range and backyard flocks and poultry holdings near wetlands as being most at risk. It also makes a series of recommendations on how to reduce the probability of H5N1 spreading to domestic poultry.

EFSA has published this scientific assessment with regard to the urgent need to provide scientific advice for the management of risks associated with migratory birds. A more comprehensive scientific opinion is expected to be adopted by the AHAW Panel on 26-27 April.

While other possible pathways for the introduction of AI also exist (covered in detail in the AHAW Panel’s previous Opinion on avian influenza[), the present scientific statement concentrates on the role of wild birds in the spread of the disease in the EU. According to the AHAW Panel, some species of wild birds (mainly waterfowl such as ducks and swans) are definitely carrying H5N1 and are considered to be responsible for its introduction in the EU. There is increasing evidence that H5N1 can be present in several species of wild birds (e.g. ducks, sparrows, swans) without them showing clinical signs. There is therefore a high probability that the virus could be carried over long distances by wild birds (especially migratory birds).

The risk assessment includes a list of wild bird species which are most likely to transmit H5N1 to other bird species in the EU following a period of migration outside the European Union. It also identifies those bird species that live in proximity to domestic poultry and which are more likely to expose domestic poultry to H5N1 through either close contact or shared water and soil. The scientific statement also assesses the probability of wild birds infecting domestic poultry in the EU with H5N1. The Panel considers there to be a high risk for free-range flocks and backyard holdings or any other production system not having high biosecurity measures. While the risk is considered to be low for indoor poultry holdings, those situated near to wetlands are considered to be more at risk.

The risk assessment covers recommendations to reduce the probability of transmission of H5N1 from wild birds to poultry in the EU through increased surveillance of the EU wild bird population and a review of biosecurity measures for all types of poultry holdings. Biosecurity measures should include:

• evaluating hygiene measures in poultry holdings;
• preventing access of wild birds to poultry holdings;
• ensuring that poultry does not have access to water and feed accessible to wild birds;
• avoiding the location of new poultry units near migratory waterfowl refuges and strengthening biosecurity measures for existing ones situated close to these;
• keeping poultry inside in areas where H5N1 infection is likely to pose a threat;
• and, in the areas where there is an outbreak, suspending the hunting of wild waterfowl and encouraging the public to take basic hygiene precautions.

The full text of the scientific statement is available on the EFSA website.