Badger TB vaccination: a practical and humane alternative to culling

Derbyshire Wildlife Trust (DWT), in partnership with the National Trust, has developed the largest badger TB vaccination programme in England.

The project has been running since 2014 (with a gap in 2016 because of vaccine shortages) and has vaccinated more than 700 badgers on more than 10,500 hectares of land.

It is proving vaccination is a practical alternative to culling badgers.

Both culling and vaccination involve trapping badgers, and share the same practical considerations. Once in a trap, badgers are vaccinated and released instead of being shot.

The BVA has rejected free shooting as part of a badger cull on the grounds it is not humane¹. Furthermore, the 2018 Godfray report on bTB control strategy identified the desirability of moving from lethal to non‑lethal control measures for TB in badgers² – and this view is likely to be shared by the public, particularly when an alternative to culling exists.

The Government has recently responded to the Godfray report and will move TB control policy towards vaccinating badgers, rather than culling³.

This article reviews the evidence supporting the effectiveness of vaccinating badgers against TB, describes the practicalities involved, and considers future opportunities and obstacles.

Effectiveness of badger TB vaccination

Badgers are vaccinated against TB using a live BCG vaccine also used in human vaccines.

A licensed badger TB vaccine also exists, which has been demonstrated in trials to be safe and effective⁴. It reduces the severity of the disease⁵, shedding of the organism and new infections in unvaccinated cubs (by 79%)⁶.

An unlicensed alternative BCG vaccine has been used in the past three years because of the lack of availability of the licensed vaccine. DWT was instrumental in obtaining the import licence for the alternative vaccine – or badger vaccination would have been stalled for longer.

Many of the safety and efficacy studies were conducted by the APHA during field studies at Woodchester Park in Gloucestershire.

Protection against the disease is not complete, but, over time, vaccination will reduce the number of new cases and facilitate the development of herd immunity, making it less likely that TB can become established.

Badgers have a lifespan of between three and five years, so a four-year vaccination programme will have a significant effect in reducing disease incidence in badgers or protecting a population against infection.

It has been estimated from studies in Ireland that capture rates greater than 30% should lead to a decline in TB in the badger population. In Derbyshire, we estimated our capture rates to be well above this figure – around 60% to 80%.

Survival in the environment of the BCG organism is low, and it is only very rarely excreted in low numbers by vaccinated animals and will not be at levels where interference could occur with the skin test for TB in cattle.

Studies have not been conducted that consider the effect of badger vaccination on TB incidence in cattle, but every reason exists to suppose vaccination will help reduce – or eliminate – this wildlife reservoir as long as it is not reinfected by cattle. It will also protect badger populations from becoming reservoirs of infection – something culling cannot do.

Other disease control measures will also be crucial in any TB disease management programme as the wildlife reservoir is only one small part of the epidemiology of the disease, with cattle movements and limitations in testing being other critical elements.

Vaccinating badgers

Badgers are a protected species and any interference with them requires a licence from Natural England. Under this licence, those engaged in the project are required to have had approved training in surveying, prebaiting and trapping. Laypeople can also be trained to vaccinate.

The comprehensive training programmes cover badger ecology, health and safety, biosecurity, and how to store and administer vaccines. The APHA runs these training programmes, which are now often held in Derbyshire because of the scale and success of the badger vaccination project there.

In Derbyshire, the Wildlife Trust has worked with a group of about 100 volunteers, without whom the project would not have been possible. They have worked with 46 landowners and 16 vaccinators are now licensed – 3 of whom are veterinary surgeons. The coordinator, Debbie Bailey, won the International Fund For Animal Welfare 2018 Animal Action award for her work on the project.

The work has been funded in part (50%) by Defra under the Badger Edge Vaccination Scheme (BEVS) and partly by donations from the public, together with some contributions from participating farmers.

The rationale behind the BEVS is that by vaccinating badgers around the boundary – between areas where TB in cattle is very low and where it is more prevalent – a buffer of vaccinated badgers could help limit the spread of the disease by preventing a wildlife reservoir developing. Unfortunately, no investment has been made in monitoring or research to investigate this hypothesis.

The practice of vaccinating badgers involves, firstly, surveying the land to establish where badger setts are located and to find signs of current activity – including by identifying latrines and main movement routes – to estimate numbers (Figure 1). Camera traps are used to help both in identifying the main areas of activity and to establish badger population numbers, which then helps determine capture rates.

Once the badger activity in an area has been mapped and high use areas identified, a three‑stage process takes place over 10 days:

• prebaiting
• trap deployment and prebaiting
• trap setting

Under any Natural England licence, this has to take place between May and the end of November.

Prebaiting takes place over the first three days, with peanuts – a favourite with badgers – being placed under stones along routes identified to be well-used by badgers. A stone is used because badgers, but not other species such as squirrels, can move a stone to access the peanuts.

Days four to eight involve trap deployment at these sites, with the traps open and peanuts being placed under a stone that is gradually moved further into the trap (Figure 2).

On days 9 and 10, the traps are set. They are inspected as soon as it gets light the following morning, and any badgers in the traps vaccinated and released (Figures 3a and 3b; video). Badgers are clipped and stock marked in case they enter a trap on the second night.

If weather conditions are adverse, such as heavy rain, trap setting is delayed so badgers are not left out in very wet conditions.

While in the traps, badgers are also checked for any signs of serious ill health before release. Participants, vehicles and equipment are cleaned before moving to a new area.

Having good surveying data – which relies on skill and experience, coupled with camera trap evidence – can result in very good capture rates, which we estimate to be greater than 60%.

Future opportunities and obstacles

The work in Derbyshire shows badger vaccination can give farmers an additional practical option as part of TB control in their cattle.

To increase confidence in – and use of – badger vaccination, the following are required:

• Information for farmers and veterinary surgeons about the theory and research behind badger vaccination, and what it entails. This is currently rather ad hoc, and would be facilitated by a central contact point and online resources to explain how to go about vaccination.
• A more strategic approach to identify how best badger vaccination could be deployed. This may include, for example, a full edge vaccination scheme where farmers are required to participate to help create a disease barrier; vaccination of an isolated hotspot, such as East Sussex, to contain the disease; ring vaccination around new outbreaks; and as part of disease control in high‑risk areas. All would benefit from associated research and monitoring.
• A new funding model, because an extended disease control system cannot rely on voluntary donations and – as the Godfray report concluded – farmers should be investing in disease control measures on their own farms. Ideally, “vaccination companies” could be formed in the same way “cull companies” are now. The economics of either approach should be similar, with the costs of the vaccine being offset by lack of carcase disposal and firearms costs. A financial benefit exists to the public in vaccination, because the policing costs required for culls – which frequently face public opposition – will not be required.
• Progressing an oral vaccine for badgers that would be easier to use. Work on developing an oral vaccine for badgers has demonstrated a protective immunity can be stimulated⁷ that is safe and not transmitted in the environment⁸. These studies involved direct administration to captured badgers. Work is now needed to develop baits that can be deployed in the wild, and will be effective and reliably taken by badgers without affecting non‑target species.

DWT – along with many other Wildlife Trusts and badger groups in England – have worked to operationalise a TB disease control option that is beneficial for both wildlife and farmers. It would not have been possible without the enormous contribution of many volunteers.

It is now time for Defra and the farming community to build on this foundation, which has the potential to bring added benefits by adding value to “badger-friendly” dairy products.