Bovine tuberculosis (TB) is one of the most serious animal diseases affecting the cattle industry in the UK. The badger is a well recognised wildlife reservoir of TB and therefore controlling the spread of this disease from badgers to cattle is a key requirement for eradicating the disease in cattle. BadgerBCG, the first TB vaccine for use in badgers, has been shown to reduce the severity of disease in individuals and reduce the shedding of Mycobacterium bovis, the causative agent of TB. Despite limited use, there is much media and public interest in badger vaccination and it is very possible that veterinary surgeons will be asked to provide advice on its use. This article explains the practicalities of the use of BadgerBCG, the role of the veterinary surgeon in prescribing and directing the use of the vaccine, and the role of lay vaccinators and how they can work to vaccinate badgers under the direction of the veterinary surgeon.
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Eleanor Brown graduated in 2005 from the University of Cambridge. She worked in mixed practice before studying for an MSc in the control of infectious disease in animals at the Royal Veterinary College. She joined Defra (now the AHVLA) as a veterinary adviser in January 2010 and currently works in the TB Programme.
Rory Cooney is a microbiologist with doctoral and postdoctoral experience working with Mycobacterium tuberculosis and Mycobacterium bovis. He worked for the AHVLA where he was responsible for coordinating the licensing of the badger TB vaccine. He now works for the Veterinary Medicines Directorate in the Biologicals Assessment Team.
Fiona Rogers qualified in 1983 from the University of Glasgow. She went into mixed and small animal practice, working in the UK, Botswana and Hong Kong. She joined the State Veterinary Service and since 2010 has been a veterinary adviser at Fera. She trains lay badger vaccinators and is involved in researching oral bait delivery.
BOVINE tuberculosis (TB), caused by Mycobacterium bovis, is a serious infectious disease of cattle in Great Britain, particularly in the south-west and Midlands of England and south and mid-Wales. Bovine TB has both public health implications and major economic consequences. Studies have demonstrated conclusively that the European badger (Meles meles) is a wildlife reservoir of the disease and contributes to the incidence of disease in cattle in these regions of the country (Independent Scientific Group on Cattle TB 2007).
The injectable Bacille Calmette-Guérin (BCG) badger vaccine, BadgerBCG, is the first tuberculosis vaccine authorised for use in badgers in the UK. Vaccination of badgers aims to reduce transmission of TB between badgers and from badgers to cattle by reducing the incidence of disease in badger populations; it also aims to reduce the severity of disease in, and shedding of bacteria from, infected individual badgers.
BadgerBCG has been in use in the Defra-funded Badger Vaccine Deployment Project (BVDP) in the Stroud area of Gloucestershire since July 2010 (Fig 1). A primary aim of this project is to provide training for lay vaccinators in all aspects of trapping and injecting badgers, who can then be licensed to trap and vaccinate badgers commercially outside of the project area, following successful completion of the course.
Further information on the BVDP is available online on the Defra and the Food and Environment Research Agency (Fera) websites at www.defra.gov.uk/animal-diseases/a-z/bovine-tb/vaccination/ (accessed February 26, 2013) and www.fera.defra.gov.uk/wildlife/ecologyManagement/bvdp/index.cfm (accessed February 26, 2013).
BadgerBCG is licensed under a Limited Marketing Authorisation (LMA) for the active immunisation of badgers to reduce TB lesions caused by M bovis (Box 1). The vaccine is for use in badgers from the age when they first emerge from the sett (in the south of England this is around April, when the badgers are approximately six to eight weeks old).
Box 1 Limited Marketing Authorisations
The authorisation for BadgerBCG (MA number 03326/4021) is a Limited Marketing Authorisation (LMA). LMAs are intended to be used in the case of veterinary medicines which, by the nature of the indicated species or the nature of the condition they are preventing or treating, are not expected to be sold in sufficient quantities to warrant a company generating the necessary data to support a full Marketing Authorisation (MA). The VMD introduced LMAs through the Veterinary Medicines Regulations 2009 in October 2009. Further information on LMAs for veterinary products can be found in the Veterinary Medicines Guidance Note Number 2 available online at http://www.vmd.defra.gov.uk/pdf/vmgn/VMGNote02.pdf (accessed February 26, 2013)
The recommended dose and route of administration of BadgerBCG is 2 to 8 × 106 colony-forming units (cfu) of BCG (the manufacturer's specified range) intramuscularly, which is a 1 ml reconstituted vial per animal. Intramuscular administration has the practical advantage of being relatively easy to perform on trapped wild badgers, without the need for sedation or anaesthesia.
Duration of immunity
Onset of immunity is stated on the summary of product characteristics (SPC) to be 17 weeks, which is the earliest that badgers have been experimentally challenged after vaccination. Although not directly correlated with efficacy, an immune reaction to the vaccine is seen in vaccinated badgers two weeks after injection. Although the duration of immunity is unknown, annual vaccination on a population basis is recommended in view of the estimated 30 per cent rate of turnover of the badger population, which includes the introduction of new cubs, badger movement and death.
Further product information is available in the SPC which is available online on the Veterinary Medicines Directorate's (VMD) Product Information Database at www.vmd.gov.uk/ProductInformationDatabase/ (accessed February 26, 2013).
The LMA for BadgerBCG was granted by the VMD following intensive research and testing carried out over 10 years in three separate laboratory studies on captive badgers and one field study on wild badgers by researchers at the Animal Health and Veterinary Laboratories Agency (AHVLA) and Fera.
Studies have shown the vaccine to be both efficacious and safe for licence purposes. Key findings of the studies include the following:
The laboratory studies with captive badgers have shown that vaccination of badgers by injection with BCG reduces the progression, severity and excretion of M bovis (Lesellier and others 2011).
A key finding of the field study, conducted over four years in a naturally infected population of over 800 wild badgers in Gloucestershire, was that vaccination resulted in an approximately 74 per cent reduction in the proportion of wild badgers testing positive to the antibody blood test for TB in badgers (Chambers and others 2010). However, as the blood test is not an absolute indicator of protection from disease, these field results cannot be taken as a measure of the degree of vaccine efficacy.
In addition, the four-year field study showed an indirect protective effect of BadgerBCG on unvaccinated cubs born into vaccinated social groups, indicating vaccinating social groups can protect dependent cubs before they emerge from the sett and can be trapped for vaccination themselves (Carter and others 2012).
The reduced severity of disease and reduction in shedding of the bacteria from infected badgers could have the desired effect of reducing badger-to-badger transmission, thus lowering the incidence of disease in badgers and consequently decreasing the risk of transmission to cattle. However, there have been no field trials on the effect of BadgerBCG on TB incidence in cattle.
The safety data gathered demonstrates that BadgerBCG is well tolerated and produces no significant adverse effects in either captive or wild badgers when administered intramuscularly at doses in the range of 105 to 108 cfu (Lesellier and others 2006, Defra 2010). This dose range included badgers treated with vaccine ‘overdose’ (defined as at least 10 times the expected dose to be used in the final licensed product) and repeated doses of vaccines.
Vaccination in the field poses a negligible risk for non-target species because there was no evidence in any of the studies that BCG was shed or excreted from vaccinated animals and BCG was not cultured from any of the clinical samples. Also there was no evidence of widespread dissemination of BCG in vaccinated animals. This is important for cattle farms where farmers may be concerned that BCG shed from badgers may interact with the tuberculin test.
The safety data gathered from the badger studies are consistent with the recognised safety of BCG in general across a wide range of laboratory, veterinary and wildlife species (Murphy and others 2008).
Further information on badger (and cattle) TB vaccination development can be found on the Defra TB pages at www.defra.gov.uk/animal-diseases/a-z/bovine-tb/ (accessed February 26, 2013). The research section of the Defra TB web pages also contains the complete data from the injectable badger safety and efficacy studies.
Sale, supply and use of BadgerBCG
BadgerBCG can only be supplied, sold or used as part of bovine TB control measures and may only be used in badgers. It is currently only available from two suppliers (Box 2).
Box 2 Wholesalers with stocks of BadgerBCG vaccine
Centaur Services Limited
Centaur House, Torbay Road
Telephone: 01963 350005
National Veterinary Services
Unit 4 Jamage Industrial Estate
Stoke on Trent
Telephone: 01782 775555
BadgerBCG has been classified by the VMD as a prescription-only medicine — veterinary (POM-V); this means that it must be supplied in accordance with a prescription from a veterinary surgeon. The prescription of POM-V medicines and the responsibilities of the prescribing veterinary surgeon and any person licensed to trap badgers for vaccination are set out in the current Veterinary Medicines Regulations. Vaccination must be conducted under the direction of a local veterinary surgeon.
Under the current Veterinary Medicines Regulations, veterinary surgeons may prescribe BadgerBCG for use in wild badgers without first carrying out a clinical assessment of the animal or having the animal in their care, as authorised by the Secretary of State (Box 3). However, the directing veterinary surgeon has a duty of care to respond in case of any problems arising through the process of vaccinating badgers; this may involve a site visit during vaccination (see below).
Box 3 Relevant legislation
Veterinary Medicines Regulations schedule 3, part 1, paragraph 4:
(1) A veterinary surgeon who prescribes a veterinary medicinal product classified as POM-V must first carry out a clinical assessment of the animal, and the animal must be under that veterinary surgeon's care, and failure to do so is an offence.
(2) This does not apply in relation to treatment of a wild animal where the treatment is authorised by the Secretary of State.
Veterinary Surgery (Vaccination of Badgers Against Tuberculosis) Order 2010:
The conditions are that the person administering the vaccine:
is 18 years old or over and:
has successfully completed an approved course;
holds a valid certificate of competence in the vaccination of badgers by injection, granted by the course provider; and
acts under the direction of a veterinary surgeon; or
is 18 years old or over and carries out the vaccination as part of an approved course
Roles of the veterinary surgeon and lay vaccinator
Under the Veterinary Surgery (Vaccination of Badgers Against Tuberculosis) Order 2010, trained lay persons are allowed to vaccinate badgers by injection subject to certain conditions (Box 3). Veterinary surgeons should not prescribe BadgerBCG for individuals unless those persons are in possession of a valid certificate of competence to vaccinate badgers by injection, granted by the course provider, which is currently Fera. The veterinary surgeon can therefore ask to see this certificate. The training course to trap and vaccinate badgers has been approved by the Secretary of State after consultation with the Royal College of Veterinary Surgeons (RCVS). A list of individuals trained to vaccinate badgers is held by Fera (Box 4). In addition, veterinary surgeons should not prescribe a vaccine for use in the field unless the lay vaccinator is also in possession of a licence to trap badgers. In the UK, badgers are a protected species and any intervention, such as trapping for vaccination, also requires licensing by the relevant authorities (Box 4). Licences to trap badgers for vaccination will not be issued to lay vaccinators unless they have successfully completed the training course in trapping and vaccinating and hold a valid certificate of competence. It is a condition of the licence that details of the exact locations of vaccination and the local directing veterinary surgeon are submitted in writing to the relevant authority before any planned activity occurs.
Box 4 Key contacts
The relevant authorities to licence the trapping of badgers are:
Natural England in England
Welsh Government in Wales
Scottish Natural Heritage in Scotland; and
NI Department of Environment in Northern Ireland.
Further information on the field use of BadgerBCG, including the lay vaccinator and trapping training courses, can be obtained from Fera on 0844 2480073 or email firstname.lastname@example.org, or from the Sustainable Land Management Branch of the Welsh Government on 0300 0622241 or email SLMP@wales.gsi.gov.uk
Any excess stock owned by a lay vaccinator and obtained by them from the wholesaler can be transferred to another area, as long as the prescribing veterinary surgeon agrees. It is important to remember that the cold chain should be maintained when stock is transferred to ensure the product remains efficacious. The storage requirements for the vaccine are set down in the product SPC which states that the vaccine should be stored and transported at 2°C to 8°C and in the original packaging in order to protect it from light. Such requirements are covered in the lay vaccinator training course and are checked as part of the lay vaccinator audit visits.
Vaccination of wild badgers by lay vaccinators occurs under the direction of a veterinary surgeon. The RCVS guidance is that directing veterinary surgeons should have knowledge of the local area and a dialogue with lay vaccinators to ensure that veterinary direction is and continues to be meaningful, and that veterinary attendance should be available in the event of an emergency.
Veterinary attendance and pharmacovigilence
It is the responsibility of those trapping and vaccinating badgers to request (and pay for) a visit from the directing veterinary surgeon – for example, if they are in any doubt about the fitness of a trapped badger to be vaccinated and/or released, to assess a seriously injured trapped badger, or in the rare event of an adverse drug reaction. Veterinary surgeons can carry out euthanasia if deemed necessary on welfare grounds. It is the responsibility of the lay vaccinator to arrange for the correct disposal of any euthanased animals. Veterinary surgeons may vaccinate badgers themselves provided they have the appropriate licence to trap from the relevant authority, or by working with other licensed trappers. Where an adverse reaction is suspected, the veterinary surgeon and/or lay vaccinator is strongly encouraged to contact the Marketing Authorisation Holder (MAH) who may want to run further investigations at the MAH's expense. Reporting suspect adverse reactions to BadgerBCG is important both for user safety in the administration of the vaccine and for animal welfare reasons.
In practice, it would be best if the prescribing, directing and attending veterinary surgeon were the same person, thus ensuring the individual was well informed of what activity was occurring. If this is not possible, for example, when covering out of hours work, the prescribing veterinary surgeon can delegate control to a nominated responsible veterinary surgeon, such as a colleague in the same practice.
A closed season operates when badgers cannot be trapped for the purpose of vaccination. In England, this is between December 1 and April 30, inclusive. In Wales, the closed season will be stated on any licence issued, with a minimum closed season of February 1 to April 30, inclusive. This is on welfare grounds to prevent trapping of lactating females with unweaned dependent cubs and to prevent exposure of badgers during adverse weather conditions.
Potential for use of BadgerBCG in animals other than badgers
The vaccine is licensed for use in badgers and the authors do not support the use of BadgerBCG in other species. It is currently illegal to vaccinate cattle against TB, and vaccination may sensitise any animal to the tests used to detect TB. For non-bovine species, although it might be possible to use the vaccine under the cascade, there is no empirical evidence on efficacy or safety, and BCG vaccine has a very variable dose-response rate in different species (for example, one BadgerBCG dose is 10 times the human dose). There is therefore no evidence to support the use of BadgerBCG in other species.
Wholesale dealers can supply BadgerBCG directly to veterinary surgeons for administering to badgers already in captivity (eg, badger rehabilitation and rescue centres) and to hold in stock for lay vaccinators. Wholesale dealers should not deliver vaccine to vaccinating lay contractors unless they are in possession of a licence to trap badgers for vaccination, and can ask to see a copy of the licence or check with Fera to find out the lay vaccinator's status. A list of individuals licensed to trap badgers for vaccination will be held by the relevant authorities.
Vaccination of badgers against TB has the potential to help control TB in cattle by reducing the risk of TB transmission from badgers to cattle. However, vaccination of wildlife presents a unique challenge in the role and responsibilities of the prescribing veterinary surgeon as badgers are not under his or her care. Despite limited use of vaccination to date, the ongoing interest in badger TB vaccination as one way to control TB means that many veterinary surgeons might be asked about vaccination, or to prescribe a vaccine for badgers. This article has outlined some of the issues and requirements, and directed readers to where further information is available.
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