By Stephen Lister, poultry vet
It is devastating enough to lose a flock to avian influenza, or even just get caught up in a restricted area during a local outbreak, but this must be doubly worse if someone subsequently tells you that you might have avoided it. The epidemiological reports recently published by Government into the 2020/21 UK avian influenza (AI) outbreaks make sobering reading for us all on where the weak links were, but equally importantly some practical pointers for prevention in the future.
Our industry rightly prides itself on its approach to biosecurity, being the livestock sector that was the first to really embrace the importance of practical contingency actions designed to prevent disease entering and spreading on a farm. It is therefore a bitter pill to swallow when you find out that your farm might not be considered “fit for purpose” or as watertight as you thought it was in achieving that goal of effective disease control through your biosecurity programme. Our industry has certainly always tried to learn from the lessons of previous mistakes but with our recent experiences of AI it is maybe time for a further rethink.
The bad news is that the scientists are already warning us that the severe outbreaks of the 2020/21 AI “season” may be repeated sooner than we think. H5N8 virus is again being detected in wild birds around Europe. This virus seems easy to infect and maintain in wild bird populations and is also able to persist longer in the environment around farms than previous viruses. These are potent warning signs that avian influenza may no longer be a once-in-a-lifetime occurrence.
The 2020/21 outbreaks of AI were the worst on record for Europe and Great Britain, so as we enter the winter risk period again it is time to reflect on what went wrong and what went right. The standout “plus” was that even with the presence of such large amounts of such a highly contagious virus as HPAI there was no evidence that once disease had been identified on one farm that it spread to another. That is no small feat for a contagious virus and illustrates that many of our basic biosecurity procedures on and between sites can be highly effective. However, we still experienced 24 highly pathogenic outbreaks on a variety of large commercial and backyard flocks the length and breadth of the country. This has enabled, for the first time, a more comprehensive scientific and practical assessment of common failings as to how the H5N8 virus so easily gained access to poultry houses.
So what have the lessons to learn taught us and what more can we do to reduce the risk of outbreaks this winter?
In many ways this is not rocket science, but rather a “back to basics” approach and to think how small amounts of virus, or small amounts of wild bird faeces (or inanimate objects and equipment) contaminated with virus can get in contact with your birds. In previous discussions with producers I used to recommend a starting point of just having a large piece of paper, a sharp pencil and an open mind and trying to map your premises, drawing all the possible entry and exit points to determine what can get in to your poultry houses and farm. I still stand by that, but maybe in this technological era one might add a drone to that so that you can get a clear birds eye view of your enterprise, and the areas around your farm, and can then highlight the routes in and out.
Research shows that the first link in the chain is the entrance to your farm. This starts with controlling farm gates, reducing vehicles, equipment and people entering to the absolute minimum. Once inside the farm muddy tracks, potholes and puddles can be contaminated with wild bird faeces and are virtually impossible to disinfect but may be constantly walked or driven through. The AI virus is most likely to reach your birds carried on “things” rather than the wind. And remember we are talking about tiny amounts of virus in small amounts of wild bird faeces and anything contaminated with them. People and their PPE can be transmitters too – so a visitors book is a powerful tool – it tells you where people have been and where they are going. This becomes incredibly important during an outbreak as it enables APHA vets to properly assess risk from one farm to another – their tracing activities can see where the virus might have gone but also where it is unlikely to have gone and can therefore help avoid unnecessary and costly restrictions on other farms. EVERYONE should sign the visitors book on each and every visit! If nothing else it shows intent and should mean that a visitor then thinks about biosecurity on EVERY visit. If people are a risk, then other uninvited visitors are just as important – rats, mice, small birds and other animals on site may not actually be infected with the virus but can carry it on their feet, fur or feathers and find their way into the poultry shed. Control of pests on site, reducing clutter and shelter between houses, and ensuring the fabric of the buildings prevents access are essential. Clearing up spilt feed will reduce attracting wild birds and vermin on site in the first place.
Next is to think of other less obvious ways the virus can get into your poultry house. One of the primary issues has been litter bales contaminated on and under the wrapping of any bales stored outside. Once you move them inside the house you run the risk of carrying in virus on them. Keeping bales sealed, double wrapped, kept in covered areas and disinfecting wrapping before moving bales into a house are essential precautions, often overlooked on a busy day.
One thorny topic, especially when the industry is struggling with margins and hence the financial ability to invest in farms, remains the fabric of quite a lot of our poultry housing. I have been in the industry over 40 years and some of the buildings I first entered are still in use. We have an ageing population of farm buildings in many areas. Leaks in roofs, side walls, dwarf walls, doors, hatches and fan vents have been linked to quite number of outbreaks. Badly maintained buildings are difficult to clean and disinfect in the first place, allow vermin access and can allow contaminated material, especially rain and flood water to easily enter a house. Flooding can bring in significant amounts of virus contaminated sludge.
As an industry we MUST take a long hard look at ALL our facilities and make serious decisions about whether they can be considered “fit for purpose” for growing and protecting poultry as our risks of major disease and the disruption they cause increases year on year. I do not underestimate the “ask” that this is in financial commitment, but the costs associated with the loss of birds, livelihoods and international trade for the last 12 months alone is enough to make this need real.
So the messages are clear:
Think about what you are doing on your farm and between farms, where virus might be sitting on your site and how you might track it into your birds – farm Biosecurity addressing weak linksCreate clear strategies and procedures for your farm and make sure ALL staff buy in to it – basic precautions done well and consistentlyLook at and realistically assess the fabric of your buildings – are they fit for purpose? We MUST address this to keep this virus and other bugs outPrevent physically bringing virus coming into a house by making sure people, litter bales, and any equipment are clean, disinfected and free of wild bird faeces contamination
