Bovine Tuberculosis Eradication Programme
Department’s Wildlife Policy (Badgers)
Research conducted over the years by the Department of Agriculture, Food and the
Marine (DAFM) and elsewhere has shown that the eradication of Bovine TB is not a
practicable proposition in the short to medium-term because of the reservoir of
infection in wildlife and, in particular, badgers which is seeding infection into the
cattle population. This accords with the recommendation made by Francis(1) speaking
of the difficulties in final eradication, that to achieve complete success tuberculosis
had to be dealt with in all species. It is also consistent with a statement in December
2011 by the then Minister for the Environment, Agriculture and Rural Affairs in the
UK, Mrs Spellman that “no country in the world where wildlife carries TB has
successfully controlled the disease in cattle without tackling its presence in wildlife as
well”. (2)
In Ireland, the first major research project took place in East Offaly between 1989 and
1995. The risk of herd breakdowns in the removal area was significantly reduced, the
risk of a TB breakdown in a herd being 14 times higher in the control area compared
with the removal area.
(3)
In addition there was an association between the bovine
tuberculosis status and the distance to badger setts. (4) The next significant study was
conducted from 1997 to 2002 in four different areas of the country. This study, known
as the Four Area Project, involved the intensive and proactive removal of badgers in
four “removal” areas and “reactive” culling of badgers in matched reference areas.
The published results of this project demonstrated that there was a significant
reduction in TB levels in cattle following the removal of badgers.
(5)
The annual
incidence of confirmed herd restrictions was lower in the removal area compared to
the reference area in every year of the study period in each of the four counties. (6) In
particular, the total number of herd restrictions in the removal areas for the study
period was almost 60% lower than in the pre study period. (5) There appears also to be
a relationship between breakdown severity and badger removal. When the pre-study
and study periods were compared across all four counties, the reduction in the number
of major confirmed restrictions was consistently greater than the reduction in all
confirmed restrictions. (6) Further studies showed that badger removal in County Laois
between 1989 and 2005 and in the Irish midlands during 1989–2004 had a significant
beneficial impact on the risk of future breakdowns. Furthermore, these studies found
no evidence of a negative impact on the risk of TB in cattle among herds in the
surrounding area.
(7, 8)
Studies at a DNA level demonstrate that badgers and cattle
share the same strains of TB
(9, 10, 11)
and that TB levels in cattle in a locality reflect
the level of TB in the local badger population such that so called ‘greenfield’ areas
where TB is very low in cattle also have a low TB prevalence in the local badger
population. (12)
The UK has also conducted significant research into the role of badgers in the spread
of TB and the impact of the removal of badgers on the incidence of TB in cattle. The
most recent research was conducted by the Independent Scientific Group, which
directed the Radomised Badger Culling Trial (RCBT). The initial findings of the trial
showed a 19% reduction in the incidence of TB in cattle in the removal areas but a
29% increase in the areas surrounding the removal area, due it was presumed to
“perturbation” of the social groupings of badgers in the removal area. However, the
effects of the cull continued to be monitored after the cessation of culling and a report
by DEFRA in December 2011 stated that “Overall, from the first cull to five years
after the last cull (i.e. up to July 2010) there was a 28% relative reduction in TB
confirmed cattle herd incidence in the 100 square metres proactively culled areas
when compared with the survey-only areas. Confirmed TB herd incidence on the land
2 km outside the culling area was comparable with that in the survey-only areas (9%
increase in incidence).” (13)
In view of the research in Ireland referred to above, the Bovine TB eradication
programme implemented by the Department contains a comprehensive wildlife
strategy in order to limit the spread of TB from badgers to cattle. Under this strategy,
badgers are captured under licence issued by the Department of Arts, Heritage and the
Gaeltacht where they are implicated in an outbreak of TB. Capturing is undertaken
only in areas where serious outbreaks of Tuberculosis have been identified in cattle
herds and where an epidemiological investigation carried out by the Department’s
Veterinary Inspectorate has found that badgers are the likely source of infection.
Despite considerable research in both Ireland and the U.K., no test on live badgers has
proven efficacious in reliably detecting TB infected badgers and thus culling remains
the only method of control currently available. Notwithstanding that in the Regional
Red List of Irish mammals, the badger was considered of Least Concern status, and
unlikely to become extinct in the foreseeable future(14). In addition, approval to
capture a sett is contingent on the total area under capture nationally being maintained
below 30% of the agricultural land in the country.
In order to ensure that the badger culling programme takes place as humanely as
possible, the Department continually monitors damage and injury to badgers captured
under this programme. Badgers are captured using a specifically designed stoppedbody restraint by trained Farm Relief Service contractors, monitored and supervised
by DAFM staff. The restraints used in the capture of badgers are approved under
Section 34 of the 1976 Wildlife Act and are specifically designed with a ‘stop’ so as
not to tighten beyond a predetermined point and so will not cause death by
strangulation(15). All restraints are monitored daily and any badgers are removed
within a maximum of 24 hours of capture. A condition of the licence granted is that
restraints are checked before noon the next day. Capturing of badgers is not permitted
during the months of January, February and March in new capture areas. Research
undertaken by Denise Murphy et al(15) at the Centre for Veterinary Epidemiology and
Risk Analysis (CVERA) in UCD has shown that damage/injury to captured badgers is
none or minimal while in the stopped restraint and lower than with other capture
methodologies. (16)
The Department monitors the animal welfare aspects of badger culling on a
continuous ongoing basis and is also satisfied that the existing culling arrangements
and procedures result in minimal injury to badgers. Nevertheless, the intention is to
replace badger culling with vaccination when research demonstrates that this is a
practicable proposition.
With this in mind, the Department has been collaborating for some years with the
Centre for Veterinary Epidemiology and Risk Analysis (CVERA) in UCD on research
into a vaccine to control tuberculosis in badgers and to break the link of infection to
cattle. Research to date has demonstrated that oral vaccination of badgers in a captive
environment with the BCG vaccine generates high levels of protective immunity
against challenge with bovine TB(17). Field trials are also being undertaken, involving
the vaccination of several hundred badgers over 3 to 4 years, with continuous
monitoring of the population to assess the impact of the vaccine on the incidence of
disease in the vaccinated and non-vaccinated control badger populations(18). Success
in the field trials will eventually lead to implementation of a vaccination strategy as
part of the national TB control programme. However, it will be some years before the
benefits of a vaccine can be seen and therefore targeted badger removals will continue
in the medium term.
The Department is satisfied that the introduction of the badger removal policy has
contributed to a significant reduction in the incidence of TB over the past number of
years. Herd incidence has fallen from 7.5% in 2000 to 4.2% in 2012. The number of
reactors has fallen from approximately 40,000 to 18,430 during the same period. In
fact, the incidence of bovine TB in Ireland has been at historically low levels in recent
years. Notwithstanding the difficulty in attributing trends to a single factor and the
cyclical nature of the disease, the Department is satisfied that the culling of infected
badgers, which is underpinned by research studies and sound science, has led to a
significant reduction in the incidence of TB in cattle over the past decade.
January 2013
References
(1)
Francis J. 1958. Tuberculosis in animals and man: a study in comparative
pathology. Cassell & Co. Ltd.
(2)
Statement made by UK Environment Secretary of State Caroline Spelman, on 14
December 2011 confirming that the Government is to allow a badger control
programme including two pilot badger culls in early autumn 2012 to tackle the spread
of bovine TB.
(3)
Eves, J.A., 1999. Impact of badger removal on bovine tuberculosis in east County
Offaly. Ir. Vet. J. 52, 199–203.
(4)
Martin, S.W., Eves, J.A., Dolan, L.A., Hammond, R.F., Griffin, J.M., Collins,
J.D., Shoukri, M.M., 1997. The association between the bovine tuberculosis status of
herds in the East Offaly Project Area, and the distance to badger setts, 1988-1993.
Preventive Veterinary Medicine 31, 113-125.
Griffin, J.M., Williams, D.H., Kelly, G.E., Clegg, T.A., O’Boyle, I., Collins,
(5)
J.D., More, S.J. 2005. The impact of badger removal on the control of tuberculosis in
cattle herds in Ireland. Preventive Veterinary Medicine 67, 237-266.
Griffin, J.M., More, S.J., Clegg, T.A., Collins, J.D., O’Boyle, I., Williams, D.H.,
(6)
Kelly, G.E., Costello, E., Sleeman, D.P., O’Shea, F., Duggan, M., Murphy, J., Lavin,
D.P.T., 2005. Tuberculosis in cattle: the results of the four-area project. (2005) Irish
Veterinary Journal (11) 629-636.
(7)
Olea-Popelka, F.J., Fitzgerald, P., White, P., McGrath, G., Collins, J.D., O'Keeffe,
J., Kelton, D.F., Berke, O., More, S.J., Martin, S.W., 2009. Targeted badger removal
and the subsequent risk of bovine tuberculosis in cattle herds in county Laois, Ireland.
Preventive Veterinary Medicine 88, 178-184.
(8)
Kelly, G. E., Condon, J., More, S. J., Dolan, L., Higgins, I., Eves J. 2008, A long-
term observational study of the impact of badger removal on herd restrictions due to
bovine TB in the Irish midlands during 1989–2004. Epidemiol. Infect. 136, 1362–
1373.
(9)
Costello, E., O’Grady, D., Flynn O., O'Brien, R., Rogers, M., Quigley, F., Egan, J.,
Griffin, J. 1999. Study of restriction fragment length polymorphism analysis and
spoligotyping for epidemiological investigation of Mycobacterium bovis infection.
Journal of Clinical Microbiology, vol. 37, no. 10, pp. 3217–3222.
(10)
Olea-Popelka, F. J., Flynn, O., Costello E., McGrath, G., Collins, J.D., O'keeffe, J.,
Kelton, D.F., Berke, O., Martin, S.W.
2005. Spatial relationship between
Mycobacterium bovis strains in cattle and badgers in four areas in Ireland,” Preventive
Veterinary Medicine, vol. 71, no. 1-2, pp. 57–70.
(11)
Murphy, C., Costello, E., Murphy, D., Corner, L.A., Gormley, E. 2012. DNA
typing of Mycobacterium bovis isolates from badgers (Meles meles) culled from areas
in Ireland with different Levels of Tuberculosis prevalence. Veterinary Medicine
International Volume 2012, Article ID 742478, 6 pages. doi:10.1155/2012/742478
(12)
Murphy, D., Gormley, E., Collins D. M., McGrath, G., Sovsic, E., Costello, E.,
Corner, L.A. 2011. Tuberculosis in cattle herds are sentinels for Mycobacterium bovis
infection in European badgers (Meles meles): the Irish greenfield study. Veterinary
Microbiology, vol. 151, no. 1-2, pp. 120–125.
The Government’s policy on Bovine TB and Badger Control in England,
December 2011 www.defra.gov.uk
(13)
(14)
Marnell, F., Kingston, N. & Looney, D. (2009) Ireland Red List No. 3: Terrestrial
Mammals. National Parks and Wildlife Service, Department of the Environment,
Heritage and Local Government, Dublin, Ireland.
(15)
Murphy, D., O’Keeffe, J., Martin, S.W., Gormley, E., Corner, L.A.L., 2009. An
assessment of injury to European badgers (Meles meles) due to capture in stopped
restraints. Journal of Wildlife Diseases 45, 481-490.
(16)
Woodroffe R., FJ Bourne, DR Cox, CA Donnelly, G Gettinby, JP McInerney and
WI Morrison, 2005. Welfare of badgers (Meles meles) subjected to culling: patterns of
trap-related injury Animal Welfare 14: 11–17
(17)
Corner, L.A.L., Costello, E., O’Meara, D., Lesellier, S., Aldwell, F.E., Singh, M.,
Hewinson, R.G., Chambers, M.A., Gormley, E., 2010. Oral vaccination of badgers
(Meles meles) with BCG and protective immunity against endobronchial challenge
with Mycobacterium bovis. Vaccine 28, 6265-6272
(18)
Aznar, I., McGrath, G., Murphy, D., Corner, L.A.L., Gormley, E., Frankena, K.,
More, S.J.,Martin, W., O’Keeffe, J., De Jong, M.C.M., 2011. Trial design to estimate
the effect of vaccination on tuberculosis incidence in badgers Veterinary
Microbiology 151, 104-111.