Experts answer your Schmallenberg questions

Livestock producers are growing increasingly concerned over the spread of the Schmallenberg virus in the UK. Farmers Weekly held a live webchat with a panel of experts answering questions about the disease. Here are the highlights:

Do we know how the Schmallenberg virus arrived in the UK?

Ian Davies, AHVLA: The cases of Schmallenberg virus have been reported in an area potentially exposed to midges blown from the continent, which is the likely source. We are not 100% midges are the source, but it is very likely.

Could ewes on tack in Norfolk from November have contracted the disease?

Ian Davies, AHVLA: If ewes were at tack and pregnant from August to October, then they could have been exposed. From November onwards, it is less likely because midge activity would have reduced.

Is Schmallenberg likely to be made a notifiable disease and are movement restrictions going to be put in place?

Ian Davies, AHVLA: No plans to make the disease notifiable

DEFRA: Introducing movement restrictions now to contain disease could be ineffective as it may already have been transmitted by insects across the country and there are no known insect vectors active at the moment.

Knowledge on the impact of the Schmallenberg virus is still evolving but it’s likely that the costs of movement restrictions on farmers would far outweigh the costs of the disease.

Is it likely the disease will spread across the country?

Peter Jones, BVA: When the weather warms up and midges are more prevalent then we may expect further spread. But if Bluetongue is anything to go by the spread as far north as Scotland will be less of a concern.

Is it possible midges carrying Schmallenberg virus will survive over the winter at low temperatures?

Peter Jones, BVA: Hopefully this very cold spread that we are having now will curtail midges surviving the winter.

Is there a slaughter policy in place?

AIan Davies, AHVLA: There isn’t a slaughter policy for this disease

Once an animal is known to be infected is it possible for them to recover? And do sheep become persistently infected with the virus?

Peter Jones, BVA: Once the immunity is in place, it is very strong and the animals, once recovered, are not infectious. Whether it’s lifelong is too early to tell.

Falko Steinbach, AHVLA: We have no indication of a persistent infection in ewes. Ewes that have been infected and that have immunity are not able to spread the disease further.

Do you think it will become more common in cattle in months to come?

Peter Jones, BVA: As cattle that became pregnant last autumn begin to calve down in the spring we anticipate seeing cases of malformed calves as well.

Ian Davies, AHVLA: We may see more cases in cattle, but on mainland Europe there has been more disease seen in sheep.

Do you think that the number of confirmed cases is accurate or could it be that the disease is being under-reported?

Peter Jones, BVA: Under-reporting is an issue especially in the early cases where reporting to the World Animal Health Organisation required locations of affected farms to be identified. I believe that has now been sorted.

Falko Steinbach, AHVLA: The number of cases have been steadily increasing over the past few weeks.

Are any tests available?

Falko Steinbach, AHVLA: A blood test is available now to see if sheep/cattle are infected. However, outside the midge season this is not reasonable to apply.

What we are working on now is a serological test to detect a previous infection. This will take a few weeks and at first work best at herd level, not for individual animals.

Is a vaccine available?

Peter Jones, BVA: Work on vaccine development has started, although it will take about 18 months before it is available, but this is fast compared to conventional development times.

Are farmers having to pay for having suspect cases tested?

Falko Steinbach, AHVLA: At present we can offer the tests for free, which means that DEFRA is picking up the costs.

The aim is to establish where disease is and thus we are encouraging farmers to inform our AHVLA offices across the country if they have suspicious cases.

We aim less to establish the number of cases per farm, as we now that the disease has spread widely across flocks on the continent.

I need to add though that it might be that we will have to charge at some stage, but this is not my or our decision here in the lab.

What would be the best way to try and stop the spread of this disease in the shorter term?

Peter Jones, BVA: It is very difficult until there is a vaccine because the virus is present in the insect population, so the only way would be protection from biting midges and there are no licensed products available that would control midges.

Should a ban on live animal imports be imposed?

Peter Jones, BVA: Movement controls including imports are not going to help because the virus is already present in the UK insect and animal population so the disruption to trade might outweigh the benefits.

Ian Davies, AHVLA: The decision to import should be between farmer and their vet. Health certification for livestock means no animal should be consigned which is showing clinical signs of disease. The infectious period for cattle is short, therefore the risk is very low.