After a spot of ad hoc flooding, he turned his attention to spreading a bit of disease, and where better than the stockbroker belt of Surrey. Some impromptu re-plumbing on the drains of the Pirbright laboratory site shared by Merial, a veterinary pharmaceutical company and the Institute of Animal Health, the IAH, did the trick. An outbreak of Foot and Mouth disease led to eight farms being infected and just over two thousand animals slaughtered. It caused a summer of chaos for farmers, but why stop there.
On the other side of the channel rancid fetid midges, carrying a ghastly virus called Bluetongue were waiting to pounce. Actually the midges can't have been that rancid... they were well enough to fly across more than forty miles of water and pass the disease on to a Highland cow called Debbie on a rare-breeds farm in Suffolk.
Now to add to the misery of the foot and mouth restrictions which effectively brought a halt to livestock marts and agricultural shows a new set of restrictions were imposed because of Bluetongue.
I remember the day that Bluetongue was discovered was the day that the Langdon Beck show should have been happening. Langdon Beck is at the very top end of Teesdale in the North Pennines. It's a wonderful old fashioned sheep show, with just one trade stand from the local agricultural supplies company, and a bouncy castle. And lots of Swaledale Sheep.
The show had already been cancelled because of Foot and Mouth movement restrictions, and the chairman had organised a `cow day'. A `cow day' is a Dales euphemism for a massive drinking session. As I was about to join the farmers drowning their sorrows at the loss of their show, a text message from the DEFRA press office announced the arrival of Bluetongue, not unexpected but still shocking. I didn't have the heart to tell the farmers who had just lost their annual show.
Almost a year later the livestock industry is still reeling from the effects of Bluetongue. The virus causes symptoms similar to Foot and Mouth disease, but the one crucial difference is that it cannot be spread from animal to animal. Instead it is carried by a midge, the Culicoides, which sucks blood from an infected animal, and then infects other uninfected livestock as it moves around gorging itself. It affects all the animals which are susceptible to Foot and Mouth except pigs, which don't get it or carry it.
Although animals can't pass the infection directly to each other, those which have the virus are still a potential meal for a hungry midge. Because of that a series of movement restrictions were introduced, which aimed to limit the accessibility of these animals to midges. Within one hundred kilometres of an infection a Protection Zone is declared, beyond that a further fifty km is declared a surveillance zone.
Generally speaking in a Protection Zone animals can only move directly to slaughter, and are otherwise banned from leaving the area. In a Surveillance Zone animals can move freely within the zone, or from it to the Protection Zone but not to the disease free area outside. This has meant massive disruption for livestock markets, for agricultural shows and for owners of high value breeding animals who want to be able to trade them to the highest bidder.
Unlike Foot and Mouth disease, part of the control strategy for Bluetongue is widespread preventative vaccination. A vaccine against the serotype of the disease in the UK... BTV 8 has been developed and is being rolled out across the country. Farmers are paying about fifty pence per animal for the dose which they administer themselves. Animal health experts don't yet know how effective it is, but both they and the farming industry are keeping their fingers crossed.
Now however there is another threat lurking. In all there are twenty-four different varieties, or serotypes of the Bluetongue virus. The disease in the UK is serotype 8 BTV 8. What is worrying the scientists now is Serotype 1, BTV 1. It came to Europe last year from North Africa, landing in Gibraltar and killing four sheep. It then spread up the Iberian Peninsular before reaching the border with France last Autumn. Midge activity falls off when the temperature drops so it didn't get any further. Until now. Recently BTV 1 has started appearing in South West France, and is moving northwards at the rate of twenty kilometres every week.
What is particularly worrying is that the area affected by BTV 8, the one which is `over here', now overlaps with the BTV 1 area in Southern France. We're not talking mutation, but as Professor Peter Mertens from the Institute of Animal Health told me, the two varieties could end up `having sex' and swapping some of their characteristics... making the disease harder to tackle. The good news is that there is also a vaccine for the BTV 1 version of Bluetongue, as with BTV 8, however neither is effective against the other serotype. That means that if BTV 1 reaches the UK the whole vaccination process will be have to be carried out again.
The one ray of hope though is that it is unlikely that BTV 1 will get beyond Northern France this year which gives vets and the pharmaceutical companies a breathing space to manufacture more of the BTV 1 vaccine to cope with another invasion, should it happen.
Posts
No comments:
Post a Comment