Policy paper

Disease control framework for bluetongue virus serotype 3 in England in 2024

Published 23 May 2024

Applies to England

The first cases of bluetongue virus serotype 3 (BTV-3) were detected in south-east England in November 2023. As of May 2024, 126 cases of BTV-3 had been detected in that region. The last case was detected on 8 March 2024, and all are believed to have been infected in the autumn 2023 period.

This framework for England sets out the Department for Environment, Food and Rural Affairs’ (Defra’s) approach to management of BTV-3 should new cases occur in 2024. It builds upon the existing GB Bluetongue Virus Control Strategy, reflecting:

• new learning since the first detections of BTV-3 on the continent and England in autumn 2023
• modelling to understand the potential trajectory of an outbreak and how control measures may affect it
• the associated economic costs and benefits and resource implications of the outbreak and control measures the views and insight of industry stakeholders with whom there has been regular and close engagement

Though animal health and disease control are devolved matters, disease does not respect boundaries. The government and devolved administrations work closely through the UK-wide Animal Diseases Policy Group to consider and plan for animal disease outbreaks. BTV-3 has been no exception. Close working on the response to last year’s incursion and planning for 2024 continues to take place to ensure consistency of approach as far as possible. This framework recognises that England’s proximity to disease on the continent confers a likely additional responsibility on Defra to stem spread to other parts of the UK. The government will work closely with devolved administrations to support the objectives of the Great Britain bluetongue disease control strategy and the UK contingency plan for exotic notifiable diseases of animals.

The framework is an overarching guide to how any outbreak will be managed. This aims to help livestock keepers and other potentially affected businesses understand the possible effects for them individually and collectively, and to prepare as far as possible.

A safe and effective vaccine will be the most effective long-term protection against BTV-3. Defra and the Veterinary Medicines Directorate (VMD) are talking to manufacturers about vaccines under development and supply to the UK market. Vaccines have been expedited for use on the continent without the full testing and veterinary medicines authorisations we would ordinarily expect to see. Defra and VMD believe it essential that due diligence is undertaken to understand if these vaccines are safe, efficacious and can be made widely available before licensing their use in the UK.

In the absence of a safe and efficacious vaccine, aside from some potential small-scale culling at the outset to prevent disease becoming established, disease control efforts in 2024 will primarily centre on movement controls on susceptible livestock and their germinal products (semen, ova and embryos). These controls have the effect of delaying spread but cannot hold back disease indefinitely or eradicate it. As circulation becomes established in biting midge populations and their range expands over time, movement controls lose their effectiveness and will need to be modified or withdrawn. The plan therefore aims to set out some of the parameters that will be considered in stepping up or down movement controls over time. It provides an indicative cut-off point at which efforts to stem further spread may be stopped.

It also recognises the impact that movement controls can have on animal keepers and other affected businesses. It seeks to minimise burdens as far as practically possible, while maintaining the integrity of measures to mitigate risk of spread.

It is important to note that activity will be heavily guided by the veterinary and epidemiological situation at the time. Prompt and regular communications will be issued as the situation evolves. The contingency plan for exotic notifiable diseases of animals in England sets out details of:

• the structures, roles and responsibilities that are deployed in an outbreak
• the factors and evidence that are considered in decision-making

This framework focuses primarily on BTV-3 in 2024 but may be deployed should there be an incursion of another serotype.

Detail

1. Free BTV-3 tests will be available in advance of any zones being declared to those moving susceptible species to live elsewhere in Great Britain from Norfolk, Suffolk, Essex, Kent and East Sussex

Keepers in these counties are currently at the highest risk of BTV-3 from infected midges being blown over from the continent, where disease is present. Given that BTV-3 does not present clinical signs in all animals, Defra will be offering free tests for animals moving from these 5 counties to live elsewhere in Great Britain.

This will provide keepers outside these high-risk areas the option to assure themselves of the health status of the animals they are acquiring. It will prevent the possible establishment of new pockets of disease from undetected spread via animal or germinal product movements. This testing will be available as soon as the risk increases but before the first detection of disease.

Keepers will be able to request a pre-movement test from a vet contracted by the Animal and Plant Health Agency (APHA). The vet will take samples and send them for free testing at the National Reference Laboratory at The Pirbright Institute for presence of bluetongue virus (a PCR test). There will be no requirement for a post-movement test and animals will not be subject to any additional restriction over and normal standstill.

Defra would strongly encourage those sourcing animals from the 5 counties or those sending them to make use of these tests before animals are sent. This will provide reassurance of the health status of animals that may be harbouring undetected disease at the time of testing.

Keepers may of course be concerned about what happens if a positive case is found. In such a case, a vet from APHA will contact you to understand more about the history

of the animal and others on the premises. Action may be taken to control disease in line with this framework and the GB Bluetongue Virus Control Strategy, such as putting in place movement restrictions. It is recognised that this may be daunting. However, Defra would urge all those sending and receiving animals from these high-risk areas to consider the role you will be playing to help protect the livestock industry at large.

Full details of how to access the free tests, the timelines keepers should plan to and how results will be made available will be published shortly and kept regularly updated. This will include any changes to eligibility over time. If disease spreads into other areas on the continent or dependent on weather patterns, other English counties may be at increased risk. Defra will then adapt the scheme accordingly.

Free testing in at-risk counties is in addition to the existing investigations that APHA undertakes when keepers and vets report suspicion of bluetongue disease in susceptible animals. Any such suspicions must be reported to APHA immediately. Full and up to date details of the clinical signs of bluetongue and how to report suspicion to APHA is available on GOV.UK.

The free testing scheme will go live when the risk level of incursion from the continent increases. This is likely to be in the coming weeks. Defra undertake regular risk assessments that consider meteorological conditions, temperatures and prevalence of disease on the continent to understand changing risk. They will launch the scheme when the risk profile increases.

2. Seek to contain disease when first detected through limited and targeted movement controls, and potentially small-scale use of culling

In line with the GB Bluetongue Virus Control Strategy, upon our first detection of BTV-3, we are likely to try to contain and eradicate disease by humanely culling the BTV-3 positive animals. Government will pay the keeper the market value of that animal. The same approach may be taken in new, distant areas of infection, if it is believed that culling can prevent disease becoming established there.

However, culling of infected animals will be limited. Once circulation of infection in midge populations is confirmed, culling is ineffective and disproportionate.

Upon the first detection of disease, movement control zones will also be established. These prevent the movement of potentially infected animals and germinal products transporting disease to new locations outside the zone.

It is likely that any initial zones will be circles of 20km radius around the infected premises. This is the size that modelling tells us is the most effective at containing disease spread. However, the exact size and shape of any zones will be considered and determined based on the information available at the time. For example, if the first detection is inland away from the south-east coasts of England, it suggests disease may already have spread from that region. A larger initial zone may be prudent to reflect this. If clinical impacts of disease are severe, additional zones may be layered around the original one, to act as a buffer to prevent further spread.

3. The approach to movement control zones will be proportionate to the risks, kept under constant review and burdens minimised as far as possible

Controls will be lifted when circulation is widespread, and they are no longer proportionate.

It is important to note that we do not know how severely BTV-3 may affect susceptible livestock in the UK. The positive animals found in England to date exhibited no clinical signs or impacts of disease. However, the experience on the continent has been far worse, with sheep appearing to be more affected than cattle. Movement controls are therefore a precautionary tool to stem spread while Defra assesses any clinical impacts.

It will take time to monitor the situation and fully understand clinical impacts. Susceptible animals are most likely to exhibit clinical signs within 21 days of infection, with peak impacts likely around day 8 or 9. However, impacts like milk yield reductions may last much longer. In the Netherlands, milk drop was experienced for approximately 9 weeks after the onset of clinical signs but could last longer depending on stage of lactation.

Defra may only have small numbers of clinically affected animals to observe at the outset. They therefore expect zones to remain in place for around 3 months while they ascertain the impacts of infection upon animals and carry out surveillance. Assuming that there is no further geographical spread, and if clinical impacts are minimal or absent, movement controls would be modified or lifted. If clinical signs are severe, then expanded or additional movement control zones may be established to slow further spread.

Movement control zones necessarily have the impact of restricting business as usual for movements of susceptible animals and germinal products. Movements out of zones or within them are prevented unless licenced by the Secretary of State to go ahead. This may be done under general, specific or individual licences. A general licence is one that does not need to be applied for so long as the person acting under it can meet any specified conditions (for example, using insecticide). An individual or specific licence is one a keeper needs to apply to APHA for. The keeper will need to set out the move requested, why, and provide information about the animals or germinal products. APHA must approve such licence applications before the move can take place. They may also apply conditions to the move, such as requiring animals to test negative for disease before moving.

While ensuring the integrity of movement controls, the following provisions will apply in the approach to movement control zones, so that impacts are minimised as far as possible.

a. Movement control zones will be no bigger than is necessary to contain and slow disease spread. Modelling suggests 20km is the optimum starting size, as it prevents animal movements transporting disease long distances. It also puts fewer farms and businesses under restriction and does not divert APHA from other priority work, for

example, on TB. However, zones may be different sizes or expanded to reflect the situation on ground, such as gradual spread within a region, uncertainty about geographical spread or access to markets.

b. Movements of susceptible animals will be permitted within zones with minimal to no restrictions. After an initial assessment of the extent of disease spread in the zone, movement will be permitted the zones. This will mean they can move to graze, attend markets or abattoirs within that zone without restriction. Positive animals or premises may be restricted from leaving their farm while Defra ascertains severity of disease.

c. A general licence will permit movements direct to slaughter from within movement control zones to an abattoir in England designated to take animals from these zones. This means keepers will not need to apply to APHA for a movement licence or undertake BTV-3 testing before moving their animals, providing they are not showing clinical signs. The conditions required by the general licence will be kept to the minimum necessary to ensure risks are managed. For example, conditions could include:

• applying insecticide to the vehicle transporting the animals to minimise risk of infected midges being carried outside the zone
• requiring movements at the times when midges are least active

d. Most movements of susceptible animals from areas free of BTV-3 into a BTV disease control zone will be freely permitted. This will allow keepers to acquire new stock. The only exception likely is movements of susceptible animals into a zone to attend a show or agricultural event if they are expected to exit again several days later. This would place those animals at risk of infection knowing they were soon to travel back outside. Tests would be unlikely to pick up the early stages of any infection acquired because of the short window the animal was in the zone.

e. Movements of susceptible animals from disease control zones to live outside in free areas in England, or movement of their germinal products, will be permitted. This is subject to those animals undergoing pre- and post-movement tests to ensure they are clear or remain clear of BTV-3. The reason for a post-movement test is to pick up any infection that could have occurred between the pre-movement samples being taken and the movement taking place. The test will therefore need to take place at the destination premises. If there are additional buffer zones around a movement control zone, pre- and post-movement tests will also be required for movements from:

• the movement control zone into the buffer zone
• the buffer zone into the free area

Additional buffer zones may be in place to stop spread from the buffer area because clinical impacts are severe, for example.

f. BTV-3 tests to enable movements out of movement control zones will be provided to keepers for free. The samples will be tested at the National Reference Laboratory in Pirbright or at the bluetongue Official Laboratory in Weybridge. Results that show animals do not have BTV-3 will mean those movements can take place.

g. Keepers can now use a new online licensing service to apply for an exemption from animal disease movement restrictions. This service will allow keepers to provide all the necessary information upfront, track progress and speak to APHA’s licencing team.

As any outbreak progresses, the deployment of APHA resources will be adapted to ensure the approach remains appropriate and proportionate. To that end, if disease became widespread:

a. APHA would prioritise visits to premises in BTV-3 free areas where keepers suspect the disease. They would also reduce visits to premises within BTV-3 disease control zones where disease is known to be present. This would ensure resources are prioritised to areas that will have the greatest impact. In areas where disease is known to be circulating, APHA might instead consider:

• not attending reports of suspicion of disease where other diseases that may have similar clinical signs can be confidently ruled out
• delegating to private veterinary surgeons who may take samples for testing

b. APHA would prioritise tracing animals that have moved from a known positive premises to a premises in a BTV-3 free area over those moving within a disease control zone. There is less benefit to tracing animals in a known infected area than there is in tracing them to entirely free areas a long distance away. This approach will ensure resources are prioritised to areas with the greatest potential impact.

c. APHA would not seek to test all animals on farm with a known positive animal. Early on in any outbreak, they might test all animals on a premises to inform the risk to surrounding areas. This would help APHA to best observe impacts in known positive animals and to understand on-farm prevalence and spread. Beyond this, whole-herd or flock testing is unnecessary and unlikely to be carried out.

The trajectory of any outbreak is highly uncertain. We do not know when and where the first case may be detected, nor how quickly it will spread. As a primarily midge-borne disease, we know disease is likely to spread geographically over time, even with the mitigation of free testing and movement controls. It is important therefore that controls remain proportionate, and that when they no longer are because circulation is widespread in multiple locations, those controls are lifted.

It is difficult to specify precisely when that may be, given the many uncertainties. As an example, Defra anticipates that when disease is present in at least 4 geographically distinct locations across England, controls will be modified or lifted. However, the situation will be kept under constant review. The views of industry stakeholders will be routinely sought and the position of partners in Scotland, Wales and Northern Ireland carefully considered too.

4. Focusing additional government support on vaccine availability and deployment

A safe and effective vaccine is the best way to protect susceptible species from the effects of bluetongue and to slow its spread. It may in time support the re-opening of now-closed trade routes.

Defra is engaged with pharmaceutical companies to gain access to safe and effective BTV-3 vaccines. They have recently published a Prior Information Notice seeking further information from a greater range of manufacturers. They are also regularly speaking with sector representatives for their insight and views.

From those conversations, it is clear that confidence in the safety and efficacy of any vaccine is of paramount importance. This is not only for the success of seeing good take-up among keepers, but to protect the sector’s exports of beef, lamb and dairy. Vaccines recently approved for use on the continent have emergency use approval but not market authorisation. This is an important distinction: vaccines without market authorisation may affect the sector’s ability to export meat and dairy products to some trading partners.

The availability and deployment of vaccine will therefore be influenced by:

• the disease circumstances at the time
• the type of veterinary medicines approval that is available
• the volume of stock available to the UK market
• the views of sector representatives
• the appetite and adoption of vaccination by keeper