Schmallenberg

I read an article recently saying that the above virus is now being noticed in the deer population. Has anyone seen eviddence of this and can anyone comment on how it will affect the preparation of the carcass for the food chain. The parent carcass not the affected offspring of course.

There is a link to an article relating to the virus, but I can find little comment o nthe spread to the deer population.

http://www.tandfonline.com/doi/full/10.1080/00480169.2012.738403
 
It will have no effect on the food chain. SBV has not been recorded affecting humans, or, based on similar viruses, is it likely to. Infection is only by midge bite, hence no risk to humans from meat. A survey done in Belgium of 500 red and roe carcasses found evidence of SBV antibodies in deer. The defects seen in cattle and sheep probably will happen, but we are unlikely to see it as the offspring will be scavenged. A nice explanation of how roe kids are unlikely to be affected is below. (The placentome is the attachment of the placenta to the uterus)

Because the virus can infect the fetus only after the first placentome has developed and because roe deer embryos remain in diapause until January (
7
), it is unlikely that SBV has contaminated many roe deer fetuses. Because 90% of roe deer were already SBV positive in mid-December and because circulating antibodies prevent transplacental passage of the closest phylogenetic relatives of the virus (
8
), we suggest that roe deer fetuses were probably not infected. On the contrary, red deer mate in September, and the first functional placentome is established by the end of October (
9
); thus, 80% of pregnant red deer were exposed to the emerging virus when placental transfer was possible. Furthermore, 35% of pregnant red deer were infected in November and December, i.e., after establishment of the first placentome and before the fetus was immunocompetent. By extrapolating the rate of transplacental infection among cattle (
6
), we determined that 28% of these pregnancies resulted in contamination of the fetus, i.e., 10%, of expected pregnancies. Because unrestricted replication of Simbu-like viruses occurs in the central nervous system of immunologically incompetent ruminant fetuses (
1
), which can lead to a typical arthrogryposis/hydranencephaly syndrome, a 10% loss among fawns can be expected in 2012.
 
I thought that was the case regarding spread to humans, but I just wandered what the butcher might think.

I understand that it can cause difficulties during birth and may cause hte death of the mother, is there something that we as stalkers could do to lessen the impact of it spreading and the difficulties it causes?

Good for Roe, but not so for Red. Is ther any statistics on the occurance of it in the wild deer population?
 
UNlikely for the butcher to be concerned - the same risk (i.e. none) applies to beef and lamb.

As stalkers, we can't do anything (nor is there much one can do other than vaccinate livestock)

The paper I quoted from had figures of about 40% with positive samples
 
I listened to the radio yesterday and there was a government press release saying that they did not consider it to be serious enough to make it a notifiable disease. I look forward to hearing more on this subject.

​Simon
 
There is no point making it a notifiable disease because it has spread everywhere very quickly and as it is spread quickly by midges then there is no way of keeping the disease out.
 
To my mind this is a red herring. We are only supposed to shoot does when the foetuses are small. We cannot test for the disease so how would we know the foetus has it? After the birth the offspring is most likely going to die and its mother will be 4 months or so before she can be shot so once again you just would not know.

Dont worry about it
 
On the basis of the roe does I shot during March, in those that were carrying foeti they all appeared normal. Likewise with the muntjac.

Having not seen Schmallenberg, would I be likely to notice the deformation at any stage of the foetus development, or typically is it not apparent until shortly before birth? Sorry if it's a stupid question, but I have no idea and am interested.

willie_gunn
 
There is a letter in this week's Vet record detailing blood sampling of wild deer. Of 66 samples from East Anglia (varied species) approx 14 positive and 2 inconclusive (20%) This is lower than studies in continental Europe (43% and 49%). No foetal abnormalities found.
 
To my mind this is a red herring. We are only supposed to shoot does when the foetuses are small. We cannot test for the disease so how would we know the foetus has it? After the birth the offspring is most likely going to die and its mother will be 4 months or so before she can be shot so once again you just would not know.

Dont worry about it

I was under the impression you should be able to see it in unborn Fawns/Kids as soon as they have limbs.
 
I was under the impression you should be able to see it in unborn Fawns/Kids as soon as they have limbs.

Yes.

There is a narrow window of susceptibility - The critical stage of pregnancy for infection to occur in sheep is between days 25 - 50, and in cattle between days 70 – 120. Cows pregnant ~280 days and sheep 147 so a window of less than 20% of the pregnancy. Animals early pregnant in times of most midge activity most susceptible Sept/Oct.

The infection moves to the nerve cells and causes the deformities as the calf grows. I honestly don't know what stage abnormalities would be grossly visible, but please do look! The recent calves I have delivered would not have been born naturally and the dams would have died.

SBV3.jpg


schmallenberg-ahvla.jpg


note the stiffened flexed legs that will not straighten.
 
Out of curiosity, if we do look and do think something is up, then what?

I accept that at the end of doe season the foetuses are fully formed but they are relatively small, not usually furry etc. In the case of my mutant lamb it was suggested that it was perhaps simply a non-schmallenberg mutant. presumably this would still be an option in deer too?

The other issue as I recall from conversation is that the foetus is only affected at the time of infection so a deer that has been bitten but had a full immune response would be cured but still show antibodies. This however is no pointer that it would have had or carried a diseased youngster. Moreover a deer once bitten and then recovered will not have a mutant youngster from then on, regardless?
 
Out of curiosity, if we do look and do think something is up, then what?

I could try and get your name in the Vet Record rather than just having you referred to as 'the stalker'? :D

We know deer can mount an antibody response. We don't know if it causes malformations in the species. The AHVLA (who were the VLA) would be interested in testing the foetus. Confirmed foetal deformity in any species of deer would advance the scientific knowledge on the disease if nothing else.

I accept that at the end of doe season the foetuses are fully formed but they are relatively small, not usually furry etc. In the case of my mutant lamb it was suggested that it was perhaps simply a non-schmallenberg mutant. presumably this would still be an option in deer too?

Absolutely. There have always been some freaky sheep born. The sheep at greatest risk were those lambing in January.

The other issue as I recall from conversation is that the foetus is only affected at the time of infection so a deer that has been bitten but had a full immune response would be cured but still show antibodies. This however is no pointer that it would have had or carried a diseased youngster. Moreover a deer once bitten and then recovered will not have a mutant youngster from then on, regardless?

You'd think, but it doesn't look like SBV is going to quite behave as well as that. When they have done (very limited) serology on infected farms the disease has spread to a large percentage of animals. Farms that had large numbers of deformities in 2012 should have a good degree of resistance and then we'd expect that the ewes would lamb normally in 2013. This has not always been the case and some farms have experienced similar problems two years in a row (and not just in young, unexposed sheep). There is suggestion that antibodies might not be as protective as we thought. There are all sorts of implications for vaccines (that at least 2 companies are working hard on producing).

To confirm foetal infection with SBV they are running tests that look for the virus itself. You are absolutely correct that an antibody titre could be historical. It's important to remember that this is a very new disease and we are still in the very steep part of the learning curve!
 
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