WHERE IS IT IN EUROPE AND HOW HAS IT GOT HERE?
SOME QUESTIONS AND ANSWERS
IS THE VIRUS INFECTIOUS TO HUMANS?
Almost certainly not. Some members of the group ARE pathogenic to man, but all of those contain a gene sequence which is absent from SBV. It is thus thought that it is unlikely that this will be a zoonosis. However, pregnant women are advised to avoid farm animals wherever possible, especially at calving/lambing/kidding time, due to the risk to their child from other diseases.
IS SBV NOTIFIABLE?
Not in most countries, including the UK. It IS notifiable in Holland. Farmers are however being encouraged to report suspect cases to AHVLA. testing for SBV is free in England and Wales, but is charged for at the usual rates by SAC laboratories in Scotland. There is concern that some farmers are choosing not to report suspect cases due as they see it to the risk of being “Stigmatised”. That is considered by many to have led to the disease being under reported, but by how much is difficult to estimate.
IN THAT CASE SHOULD WE NOT BE DOING SURVEILLANCE?
No surveillance plans have yet been published in the UK. That is largely because serology testing has yet to be fully developed as yet, though the time when it will be seems now to be close. When a sufficiently accurate and cost effective test is available then there will almost certainly be some level of surveillance, but just what that might be is at present a matter of conjecture
WHAT PERCENTAGE OF FOETUSES ARE AFFECTED?
Again this is not known because no figures have been kept. Anecdotal evidence suggests anything from a small percentage, perhaps only one or two animals on some farms, up to 50% on others. We shall not really know in the UK until the end of April for sheep, the end of May for goats, and the end of June for cattle just how many animals have been affected on any given farm. The use of a serological test under trial in Germany suggests that on affected farms, a very high percentage of animals are seropositive.
IS THERE A VACCINE?
No, Not yet. This is a new virus and the earliest time we can hope for a vaccine to be available is likely to be late 2013.
SO WHAT MIGHT HAPPEN LATER THIS YEAR AND IN 2013??
That is the big question!. It depends very much on the great unknown of how it will overwinter, or indeed at one end of the scale of possibilities, will it overwinter at all at mid European latitudes?. Once an animal is infected, the viraemia lasts only for 2 to 4 days, but we have no idea how it behaves in the insect vectors. It is still possible that this virus could simply die out, but the concensus of opinion, including that of the Chief Veterinary Officer, is that the virus will reappear next year, and in the UK will push westwards and northwards as midges are carried by the wind.
If it follows the pattern of closely related viruses such as Akabane, then what seems to happen is that there is a severe effect in the first year that a new population is infected, but that after that most animals will be resistant, and clinical disease falls to a low level. Note the word IF please!.
The reporting, while I write, of SBV in Andalucia, southern Spain suggests that this virus WILL overwinter. It is not now a question of whether, but remains one of where?. It also shows that we are in a rapidly changing situation, and we need to realise that our assumptions may have to change as knowledge of the disease improves.
Cases in sheep have probably now peaked for this year in most countries, though not in the UK where lambing is later. In goats, any peak will be a little later, and in cattle it will be later again and is expected in May or June due to the longer gestation period. Different countries update the authorities at different times and different intervals, so whenever a table of infected premises is compiled, it will be out of date for some countries.
To enable a proper like for like comparison, to be made, cases are only recorded if a deformed or aborted foetus has been positive by PCR for the presence of SBV. The state of play is as of March 15th
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