If you are a poultry farmer with thousands of turkeys, or if you have a couple of hens in your garden, they need to be housed for the next month according to Defra (and the Welsh and Scottish governments too, but not Northern Ireland) to avoid encountering ‘wild birds’ carrying a new strain of bird flu (or poultry flu as we might wish to call it) H5N8.
If you read the papers you’ll pretty much get a regurgitation of the Defra press release and line (see here). It’s unspecified ‘wild birds’ that get the blame for the spread of this disease. Slightly surprisingly (to me anyway), the Daily Express seems to be covering this news better than most proper papers (see here and here).
Defra’s grasp of the biology of wild birds seems to remain at its usual abysmal level. A case in Hungary in early November where Highly Pathogenic H5N8 virus was isolated from ‘a pooled samples’ (sic) of six wild birds, 5 ‘ducks’ and a ‘seagull’, was one of the earliest cases. There are, as readers of this blog will probably know, a few dozen species of ducks which might be found in Hungary at that time of year and each of them will have come from a wide breeding area and might be travelling onward to a wide wintering area with very different possibilities of arriving anywhere near the UK. There are a few gull species too! Vets and virologists are highly specific about which strain of virus they are dealing with (I’m glad to say) but incredibly vague about the dead duck that someone had in their hands from which they isolated the virus. It’s the usual shocking treatment of the biology of an infectious disease whose biological details of transmission are important in understanding and dealing with the issue. It comes to something that whenever Defra writes or talks about wildlife they sound as though they don’t have a clue. It inspires a massive lack of confidence in their competence.
There are now upwards of 150 recent cases of wild birds being found dead and apparently carrying the relevant virus. The infected species include Tufted Duck and Pochard, Mute Swans, ‘various gulls’, ‘grebes’, Coots, Curlews and ‘some raptor species’. It’s an interesting list. The chances of a Tufted Duck directly transmitting a virus to a domestic, even a free-range, turkey seem rather low. But I’m not saying that wild birds aren’t important vectors of H5N8, it’s just that we always go through this same story of it being wild birds, with poor, in fact awful, data on the wild birds concerned, and very little emphasis being given to movements of live and dead domestic birds. Some of us will remember the case of the lorry loads of partially processed turkey meat that were arriving at a Bernard Matthews farm in a previous serious UK outbreak of H5N1 bird flu; wild birds were blamed by Defra for that outbreak until the truth emerged rather belatedly (see Fighting for Birds pp238-43).
It is interesting that many of the commercial outbreaks seem to be from large premises with thousands of birds and scattered across a wide range of countries including Austria, Netherlands, Germany, Denmark and Sweden.
One of the more interesting cases appears to be that closest to the UK, in the Pas de Calais, where ‘wild ducks’ were found to have the virus. But these ‘wild ducks’ were being used by wildfowlers as calling birds to attract wild birds into range, and so were captive ‘wild birds’ or as some might say, including the ducks themselves, captive birds. And indeed captive birds which were moved from a domestic situation to the wild and back again deliberately many times. In a fantastic Defra example of Newspeak this case is described as follows: ‘In France (Pas de Calais region and the closest case to the UK), captive decoy ducks tested positive. These birds are considered wild birds as they are sedentary and not associated with any commercial poultry’.