We on the south east went through this last year, I have dug out my notes from the sessions we attended then. We went to a further update for the South East a couple of months ago, and essdentially all that had changed was that they said that a ewe getting the viruis during the first half of pregnancy could risk her lambs being funny.
Otherwise this is last January's update in the South East:
"Key points from the meeting I went to run by Westpoint Vets with ADAS and the NFU
In the audience of 100 or so, of the 6 farmers that had started lambing 5 had deformed lambs. Rate was 5-15%.
There is a large amount of re-absorbsion from data from those that scanned – singles coming up empty, and twins only having singles – anything up to 10%
Lambs born can be stillborn, can be deformed with locked joints making it very hard for the sheep to lamb – one person said she was regularly breaking lamb legs inside the sheep to get out dead deformed lambs so as to save the sheep.
There are also what are called “silly lambs” – born live but with little brain development, so die quite quickly.
All you can do for this year’s lamb crop is cope.
As for future, all the following needs a big caveat – this is an early disease, with little history, however bluetongue spread (also by midges) gives us good data from past, and some of Europe is months ahead of us in lamb cycles so have been through it. There is also excellent cross European co-operation and information sharing.
However the following is best guestimates from informed sources. So likely to be true, but not guaranteed!
For sheep, once infected they show no signs of illness, but have it for a couple of weeks. They then have developed strong immunity to it (potentially life long!). So once a sheep has had it, it should be ok.
For cattle, they show lots of symptoms that are common with other diseases, but similarly they then have developed strong immunity to it, and should the be ok.
The issue is IF they get infected or have the virus during the first trimester of pregnancy [now the first half]. Before mating or after the first trimester [now half] and the offspring is not affected. (don’t know whether the young inherit the immunity, but if meat doesn’t matter, and for future breeding as long as they get it before mating, then they’ll be ok.
Midges are the likely source of infection, and this is borne out by Defra’s modelling of midge vs. Wind and temperature that shows most danger area is where we are seeing the virus. Midges are active only at certain temperatures, and the likely period when they can affect is march to October, although that doesn’t mean you can relax on November the 1st!! [wording for south east]
Parasite control of the flock/herd may reduce spread, but standard fly protection products don’t do midges, you need spot-on. However you are too late to help this year and see below may positively want to welcome it now, so consider this before using spot-on. If you use spot-on on a sheep, then it will kill the midge that bites it, but not before it has infected the sheep, and probably not before it has infected several others of your flock – the poison takes up to a hour or so to work, so at best you might reduce, but would not protect.
A vaccine is 1-2 years away, and probably won’t be needed as by the time it gets here, all sheep and cattle should have got it (and got over it).
If you are in the south then your strategy is that for this seasons lambing, you will have what you have got now, so cannot do anything about it. If it proves that once infected you get a long period of immunity, and for sheep there are no side effects, then maybe you should hope that all your sheep get infected during this summer, and then they’ll have protection and next year you’ll be ok, as protected sheep don’t produce deformed/stillborn/silly lambs.
For cattle in the south, the same strategy might apply, hope that they get it, that you don;t get too bad symptoms (eg milk reduction) which only lasts for two weeks in any case, and they get immunity for next year.
Those in the south will also need to consider whether they should buy in stock from the north, that will be naive to the disease (not have had it), and whether to do this earlier so that they might/should get the disease before going to ram/bull or AI.
For those outside the immediate area infected this year, it will depend on how quickly midges spread up north from infected south. If slowly, then you might get several years of uncertainty (there is no live test at the moment to see if stock has had it) as to whether your particular area has got it/your farm has got it. I did ask about deliberately infecting stock so that they get it and get over it – and this might be a possibility if vaccine doesn’t get here soon.
So that’s what I learnt. In a way you should hope that all the UK gets it this summer, and then with a long immunity the worry will disappear, although we might be vaccinating future breeding stock in their first lambing/calving season to give their young protection. "
