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Avian Influenza: The importance of biosecurity

As the current outbreak of AI continues (78 cases in England, 6 in Scotland, 3 in Wales and 6 in NI at the time of writing), the importance of good biosecurity has been repeatedly highlighted by industry, government and private vets.

Clinical Director, Richard Jackson BVMS (Hons) MRCVS shares how best to mitigate the risk through biosecurity.

The question is what constitutes good biosecurity?

In order to answer that question, we need to look at the routes of infection. Migratory waterfowl brought AI (H5N1) to the UK from Russia/Kazakhstan. These birds then mixed with our year-round resident waterfowl such as mute swans. In turn other bird species such as crows became infected, and these then travelled to poultry farms and defecated on roofs and in and around sheds.

Aside from bird scarers we cannot easily prevent wild birds from becoming infected, nor can we prevent them from defecating near poultry units. What we can do, is keep the virus outside the sheds.

There are a number of routes for virus to get into sheds:

Rainwater can wash virus in from faeces on the outside of roofs into the shed via leaks. Likewise, any leakage of water from outside the shed through cracks in the floor can wash in virus. It is essential that shed roofs are well maintained and joint/cracks in floors can be tarred at turnaround.

Wild birds could potentially enter sheds and bring in virus. In most modern controlled environments – fans usually have flaps and inlets that are baffled to prevent access. For sheds with natural ventilation ensure that sheds are wild bird proof which may require meshing the inlets/outlets. For keepers in AI zones, it is a requirement that sheds are wild bird proofed before licenses will be issued to transfer pullets or day-old chicks to the farm. This is also a requirement of the AI prevention zone that is currently in place across the whole of the UK. Also ensure any feed spillages are cleaned up immediately to ensure wild birds aren’t encouraged to visit the site.

Virus can also enter the shed with bedding. Ensure that bedding is either stored in a bird proof shed or is stored on pallets which are shrink wrapped. If bales are shrink wrapped and the pallet on which they sit is outside of the shed they are going in to, once the shrink wrap has been removed, the bales should be carefully transferred inside and not touch the ground. If the shrink wrap is damaged, the pallet of bales should not be used (this is again a requirement for APHA to issue a pre-movement license).

Another route for AI into sheds is via humans. Anyone entering the farm must sign the visitors book (if AI occurs this assists APHA determine where any in contact sites may be). Visitors should sanitise their hands, wear PPE and site dedicated boots. Ensure the poultry unit is gated and that the gates are locked when access isn’t needed to prevent anyone unintentionally entering the site without disinfecting their wheels and signing in. If vehicles are brought on site, ensure they are clean and that the wheels are disinfected with a DEFRA approved disinfectant (such as Halamid or Intercid) at the Poultry Orders Rate.

To check your disinfectant is DEFRA approved please check the DEFRA website.  

Similarly, once people are on site, we need to keep the virus from being walked from the yard into any sheds. Always ensure that there is a foot dip outside the entrance to each shed. This disinfectant should be DEFRA approved and used at the Poultry Orders Rate. It should be replenished at least twice per week and the foot dip should be covered. Where the yard is concrete or clean stone, then the boots should be washed before disinfecting them as mud/muck will inactivate the disinfectant. A boot barrier system should be in place to ensure there is no risk of virus entering the shed. Hands should be sanitised before entering the shed. Ensure any tools etc entering the shed are sanitised before bringing them in.

Rodent control is essential. Always keep records of rodent activity and rodent baiting. Ensure bait points are located on a map.

Consider the location of fallen stock storage to ensure that collection lorries cannot transmit disease to your farm. 

At the end of 2021 there was a joint industry and government workshop on AI. The presentations can be viewed here

If you would like to discuss biosecurity on your farm further, please do not hesitate to contact us on 01392 872932.

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