Bluetongue Disease

Bluetongue is a disease of ruminants that is spread by midges. In fact, it isn’t really just one disease as there are many different serotypes all causing slightly different clinical signs and with differing severity. The first time we encountered Bluetongue in the UK was back in 2007 when we had an incursion of BTV-8 from the continent; luckily, there was an effective vaccine that was deployed quickly and, in contrast to much of Europe we had no further BTV -8 cases.

So, with that in mind you may be wondering what all the fuss is about this time…….

Unfortunately, the serotype we are now dealing with, BTV -3, causes much more severe disease and we currently don’t have a licensed vaccine to use against it here in the UK.

BTV -3 swept through large parts of the Netherlands, Belgium and Germany last autumn causing severe disease and high mortality, especially in sheep; but cattle were not spared with dairies seeing milk drop of >1kg per cow/day persisting for many weeks in infected animals, and increased mortality.

Following the incursion of BTV-3 into the UK in autumn last year (surveillance findings only, no clinical cases), the government has released a Bluetongue Disease Control framework outlining the strategy should new cases occur in 2024.

Much has been learned since the first detections in the Netherlands, and this, along with modelling and industry stakeholder opinions, have been used to form the basis of this policy. There is still a great deal of uncertainty around when, where and indeed if we will see BTV-3 in the UK this year, and so the framework is necessarily flexible to reflect this.

The full framework is available at Bluetongue disease control framework set out - GOV.UK (www.gov.uk) should you wish to read it but here is a brief outline of some key points:-

• Vaccination
  ▪ A safe and effective vaccine will be the most effective weapon in long term BTV-3 control
  ▪ Vaccines are available for use on the continent under emergency authorisation BUT NOT in the UK
  Defra and VMD are working with vaccine manufacturers to license products following safety and efficacy checks but it is unlikely that we will have a vaccine available to use in this year’s risk period
  ▪ Vaccination in the Netherlands should reduce the infection of midges, hopefully meaning that fewer infected midges find their way to the UK
  ▪ Culling
  ▪ There may be some small-scale culling initially if it is felt that could prevent the disease from becoming established
  ▪ This is likely to be limited and short lived
  ▪ If BTV-3 is shown to have spread and be present in the midge population culling will not be appropriate or effective and will cease
• Movement restrictions
  ▪ This will be the backbone of the strategy with movement of livestock and germinal products (semen and embryos) restricted
  Restriction zones will likely be 20km circles around infected premises
  ▪ Movement will be allowed within zones with minimum restrictions applied
  ▪ Movement 'to live' out of zones will be permitted under license and with the animals subject to pre and post movement testing
  ▪ Movement to slaughter will be permitted under general license
  ▪ If BTV-3 is shown to be widespread and circulating in multiple locations restrictions will no longer be effective or proportionate and will be lifted
  ▪ BTV-3 testing
  ▪ Defra is offering free BTV-3 testing to keepers in Norfolk, Suffolk, Essex, Kent, and East Sussex if moving livestock out of these counties ‘to live’

The exact path taken in deploying the framework will depend on the geography and timing of any outbreak, and we will try to keep you up to date. Karen is part of the Ruminant Health and Welfare Technical Group on Bluetongue so we will be well informed.

For more information, please visit the Ruminant Health and Welfare Groups BTV resource hub at Bluetongue Virus - Ruminant Health & Welfare (ruminanthw.org.uk) where a wealth of factsheets, articles and webinars can be found. This area will also be kept up to date with any new information on the UK and European situations.

If you have any questions on BTV and how it may impact your producers, or your business Karen would be happy to try and answer them for you, please drop her an email. karenbo@nmrp.com