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"All the rumours re the vaccine causing infertility and abortion are tosh- the real and actual risk is the infection with the BTV8 virus...."

Sent to by Dr Ruth Watkins, Sept 28 2008

".....A friend rang re vaccination against BTV8 that her farming parents have not undertaken on their farm though they are situated fairly near a Welsh farm that has imported Limousine cattle from France since the 1st September when Wales became a protection zone, and that have been infected with BTV8. But they are not sure if the cattle are still infectious. Their own cattle are out and the tups are going in with the ewes next week. Clearly they don't really want to vaccinate now or they would have ordered vaccine through their vet and simply got on with it.

If they vaccinate their cattle now, say they got the vaccine from the vet and did it on Friday the 26th of September, their cattle would not be protected until the 7th of November assuming they gave the second dose at 3 weeks after the first without any further delay. The peak months for midges have passed and the risk of infection in November and December is relatively low in comparison with October for instance. Is it worth getting their cattle in to vaccinate against BTV8 now?

If the imported Limousins are infectious to female midges, these would first be infectious in October before my friend's parents' farm have any immunity in their cattle. The first generation of infectious female midges would be relatively few (the cycles of amplification have not taken place as occurs all summer long) as the female midge would take between 3 and 4 weeks to become infectious after her initial infection.

It would be very bad luck if one of her parents' cattle was bitten by an infected midge- just as my brother-in-law in Norfolk felt about his cow, Duchess, last October 2007. In fact none of his other cattle were infected as it later turned out on screening.

Is it worth the expense of vaccinating now to prevent a case of infection in the final 3 weeks of November and throughout December? I for example began vaccinating my cattle on the 5th of September as soon as I could get the vaccine from my vet - but my farm helper will not be able to come and help me get them in to give the 2nd vaccination until Monday the 29th September. This means that my cattle will not be immune until the 20th of October; the earliest date they could have been immune was the 17th October.

Now consider the sheep on my friend's parent's farm. They can be considered immune 3 weeks after the single dose of vaccine, thus if vaccinated now on Friday the 26th September for instance, they would be immune by the 17th October. However, female midges very much prefer to bite cattle so the chances of sheep being infected in late October, or in November and December are much lower than that for cattle. Is it worth vaccinating the sheep?

They are very much more likely to become ill and be severely affected than cattle - which is an important consideration. However, in 2008, now, it is clear there is not going to be a large outbreak in West Wales in which a significant number of sheep in the flock are likely to become infected and ill. If there were to be a few cases then the most significant infection commercially would be of the tups. Therefore I advised vaccinating the tups so that one would not find a flock of empty ewes when they were scanned in December/January. If a tup was infected - even subclinically - empty ewes are likely to be the result and the lambing next season will be a disaster. All the rumours re the vaccine causing infertility and abortion are tosh- the real and actual risk is the infection with the BTV8 virus.

Perhaps the same consideration might be given to the bulls but they are unlikely to be active in November /December as the spring and summer calving cows will already have been covered. On the whole they do not seem to be as severely affected as rams - and temporary infertility associated with even a subclinical infection can be expected to reverse by next Spring, for example.

Clearly it is essential that all farmers vaccinate all their ruminant stock during the winter and early next Spring.

Clearly also, it is ideal if there is money enough and the will and time to vaccinate all one's ruminants now as I have done (having written a vaccination policy (here) I could hardly do otherwise).

However the voluntary vaccination policy is less than perfect and expensive for the farmer, and the longer the farmer leaves before vaccination this autumn the less worthwhile it will become, especially in view of the BTV8 vaccination that will be required over winter and early spring of 2009 in readiness for next summer when infection must be presumed to re-emerge from a much wider area throughout England and Wales than the SE of England."

yours sincerely

(from Dr Ruth Watkins)