Memorandum submitted by the Department
for Environment, Food and Rural Affairs (P34)
PROGRESS REPORT BY DEFRA ON THE RECOMMENDATIONS
IN THE FIRST REPORT OF THE AGRICULTURE COMMITTEE, SESSION 2000-01
( HC92) "BADGERS AND BOVINE TUBERCULOSIS: FOLLOW UP"
1. This report gives an update on progress
of the Government's five point plan for dealing with bovine tuberculosis
since the Agriculture Committee's First Follow Up Report on Badgers
and Bovine Tuberculosis (20 December 2000 HC 92) and the reply
submitted by the Government (4 April 2001 HC 409).
2. The issue of TB was debated in Westminster
Hall on 21 May 2002. The EFRA Committee was given an initial assessment
by the Independent Scientific Group on Cattle TB (ISG) of the
likely impact of FMD disruption on the Krebs trial under cover
of a letter from Deirdre Kennedy of 12 June 2002 to Gavin Devine.
An update on the implementation of the former Committee's recommendations
was also put forward by Defra at year end and is published in
the Committee's Annual report (23 January 2003 HC269).
3. This paper recognises the difficulties
caused by the FMD outbreak and sets out the positive steps that
have or will be taken to address bovine TB in cattle once the
backlog of TB testing has been reduced further.
INTRODUCTION
4. The Government welcomes this opportunity
to update members of the Environment, Food and Rural Affairs Committee
on the current situation with regard to bovine TB. The Committee's
support for the strategy in general and the culling trial in particular
has been important in this difficult and emotive area. Annex A
to this memorandum provides detailed information updating the
Government's response to the follow up report of the Agriculture
Committee.
5. Since the Government's response to the
Agriculture Committee of 4 April, there have been a number of
developments which have a significant bearing on the approach
to bovine TB. Defra, which was established on 9 June 2001, is
the champion of sustainable development. This role together with
the publication of the Policy Commission report on the Future
of Farming and Food, "Farming and Food, a sustainable future",
has focused attention on the economic, social and environmental
consequences of Government policies including those in the animal
health field. In particular, the Policy Commission recommended
that:
In view of England's abysmal animal health record
in recent years, Defra in consultation with the industry need
to devise and implement a comprehensive animal health strategy.
This recommendation was accepted in the Government's
response to the Policy Commission report, "The Strategy for
Sustainable Farming and Food—Facing the Future".
6. The Foot and Mouth Disease (FMD) epidemic
of 2001 also had the effect of highlighting the significant consequences
of animal disease not only on livestock farming, but also on the
wider rural community and associated industries such as tourism.
The main report of inquiries into the epidemic, the report of
the Royal Society into the 2001 FMD outbreak, "Infectious
diseases in livestock" and the report of the Lessons to be
Learned Inquiry into Foot and Mouth Disease 2001, both supported
the recommendation of the Policy Commission.
7. Defra is therefore in the process of
developing an Animal Health and Welfare Strategy which we expect
to publish in the summer of 2003. Although the Policy Commission
Report referred to the animal health situation in England, the
development of an Animal Health and Welfare Strategy will be taken
forward together with Devolved Administrations in Scotland and
Wales. This reflects the fact that GB constitutes a single epidemiological
unit, and that the State Veterinary Service is a GB wide organisation.
A joint consultation document was issued on 8 January. During
the development of the Animal Health and Welfare Strategy, the
three GB environment and rural affairs departments will work in
partnership with industry, specialists and the wider community
to provide an overarching framework for the development and implementation
of policies in all areas of animal health and welfare. Clearly,
any Animal Health and Welfare Strategy for Great Britain would
be incomplete if it did not encompass bovine TB.
8. However, it is recognised that the process
of developing a strategic approach which takes due account of
the views of stakeholders will not be quick enough to satisfy
all concerned that the Government is doing all that it can to
address the immediate problem of bovine TB. A number of policy
options which might be introduced in the short term are therefore
under consideration. These include:
— clearer implementation of EU legislative
requirements, possibly with a more fundamental review of the powers
available under the Animal Health Act;
— review and redistribution or increases
of test frequencies in certain areas;
— tailoring TB controls according to
TB risk by area and/or herd health history;
— the introduction of pre movement
testing;
— requiring on farm management action
to reduce TB risk to cattle (for example, post movement testing
with on farm isolation, herd health plans);
— additional testing in certain areas;
— improvements in delivery of TB controls
which might be made through the development of a new relationship
between the SVS and LVIs;
— increasing the pool of people trained
to test for TB and available to deliver testing (including the
possible use of lay testers);
— streamlining service delivery processes
within SVS in order to improve efficiency and reduce administrative
delays;
— speeding up removal off farms of
cattle that react to the tuberculin test (in part by reviewing
and simplifying the compensation process).
— Some of these measures will be dependent
on the availability of SVS resources.
9. The Government remains committed to finding
a sustainable solution to the problem of TB in cattle based on
the best possible scientific basis. Some £16 million has
already been spent between April and December of 2002 for surveillance
to identify the spread of the disease and controls to remove infection
in those herds where it is found and limit further potential for
spread. In addition, Defra expects to spend £15 million on
TB related research in the current financial year. A breakdown
of expenditure since 1999-00 is attached at Annex B with an estimate
of expenditure for this year.
SUSPENSION OF
TB ACTIVITIES AS
A RESULT
OF FMD
10. In addition to the effect of the FMD
on Government thinking in relation to animal health, the FMD epidemic
has had an immediate, practical effect on the delivery of the
TB Programme. Most testing for bovine TB was suspended in late
February 2001 in part because visits to livestock premises presented
a real risk of transmission of FMD from farm to farm and in part
in order to allow resources to be diverted to combating FMD. Routine
TB surveillance and testing of herds with TB incidents did not
fully restart across Great Britain until January 2002. At the
start of 2002 the backlog of TB tests which had built up during
the FMD epidemic amounted to some 27,000 herds overdue. The clearance
of this rolling backlog of tests has made heavy demands on the
State Veterinary Service (SVS) and the private veterinary practitioners,
who as local veterinary inspectors (LVIs) carried out most of
the routine tests in 2002. At the end of December 2002 the backlog
had reduced to just over 9,000.
11. The diversion of resource to deal with
the testing backlog has entailed the delay of a number of initiatives
planned around TB test frequencies such as reviews of the frequencies
used for 2000, 2001 and 2002, increases in certain low incidence
parishes in response to isolated outbreaks and more even annual
distribution of herd test dates in parishes on four, three and
two yearly test frequencies.
12. Field based research activities, including
the surveying and trapping of badgers required for the badger
culling trial, were also suspended from late February 2001 until
the end of the year. This suspension has affected both the delivery
of the research programme and the resources available for new
projects as additional funds were required in 2002-03 in order
to recover the time lost on existing projects.
13. The diversion of staff engaged on policy
development from TB to duties related to the FMD epidemic during
2001, together with the engagement on clearance of the backlog
of tests of veterinary staff who would normally be responsible
for implementation of TB policies in the field, has made it difficult
to introduce new measures since the FMD epidemic commenced. A
limited package of measures designed to accelerate the clearance
of the backlog of tests, to ameliorate the economic effects of
movement restrictions and to pilot possible alternative controls
which might accelerate the clearance of TB from affected farms
was announced on 9 October 2002. Further measures are under consideration,
but the resources to implement such measures in the field will
only be released when the backlog of tests is eliminated.
14. A number of areas of work identified
in the Government reply to the Follow Up Report of the Agriculture
Committee have not been taken forward either because of the diversion
of resources to dealing with FMD or because the recommendations
of the Agriculture Committee will now be dealt with in a different
way. These are described in detail in Annex A.
15. In the interim, the Government has continued
to carry forward the five point plan for dealing with bovine TB
announced in August 1998. The five points are:
— improved liaison with the Department
of Health to monitor the incidence of Mycobacterium bovis
infection in humans;
— research to develop an M. bovis
TB vaccine;
— other research to improve knowledge
of the disease and its transmission to and between cattle and
other species;
— continued regular testing of cattle
herds for TB and slaughter of suspect animals, and where possible
strengthening of these controls;
— a badger culling trial to test the
effectiveness of badger culling in reducing TB in cattle.
Progress under each of the five points of the
TB plan is set out in more detail below.
Protecting human health—improved liaison
with the Department of Health to monitor the incidence of M. bovis
infection in humans
16. Normal levels of milk and meat hygiene
controls continued to be applied during the suspension of TB testing.
The incidence of bovine TB in people remains low and stable, at
around 45 new bacteriologically confirmed cases a year. About
1% of all bacteriologically proven cases of TB in humans can be
attributed to M. bovis infection and most of those are
likely to follow re-activation of latent infection contracted
prior to the introduction of milk pasteurisation or recent infection
contracted abroad. The geographical distribution of cases does
not seem to mirror the spread of bovine TB in cattle. The situation
continues to be monitored by Defra, DH and the FSA in the forum
of the United Kingdom Zoonoses Group (which has taken responsibility
for inter-Departmental co-ordination on questions relating to
bovine TB from the MAFF/DH Group on M. bovis in animals
and man).
17. With the current backlog of tests and
the increasing risk arising from the spread of TB through the
cattle population, the procedures designed to protect public health
have been improved. The main public health risk from TB would
come from unpasteurised milk sold by a retailer of raw cows' milk
(including for use in raw milk products) with undiagnosed disease
in the herd, though generally M. bovis will be present
in the milk of affected animals only in the advanced stages of
development of the disease. Where a test is overdue it is essential
that pasteurisation of all milk takes place and, in order to achieve
this, that the local health authorities be advised when a herd
test becomes overdue. Measures have been put in place to update
Animal Health Office records of producer retailers regularly with
information supplied by the Dairy Hygiene Inspectorate so as to
be able to ensure that such herds are tested annually. Similar
measures are being applied to farmers who pasteurise their own
milk as failures in pasteurisation equipment pose a similar risk.
18. Information on the risk assessments
carried out on meat by the ACMSF and on milk by the FSA and research
on the presence of the M. bovis organism in the edible
parts of carcasses are included in Annex A.
RESEARCH TO
DEVELOP AN
M. BOVIS TB VACCINE
19. The DEFRA TB vaccine development programme
consists of several linked projects located at the Veterinary
Laboratories Agency (VLA) and the Institute for Animal Health
(IAH). The long term aim is to develop a cattle vaccine and/or
(depending on the outcome of the badger culling field trial) to
develop a badger vaccine. In addition, a number of the projects
are aimed at development of a differential diagnostic test that
will distinguish between infected and vaccinated animals and development
of a blood-based immunological test for badgers.
20. The objectives of the programme are:
— to generate, select and produce candidate
vaccines for cattle and badgers;
— to develop immunological reagents
which will lead to a diagnostic test for use in living badgers;
— to use small animal models to screen
candidate vaccines for protection against M. bovis and look at
the safety and immunogenicity of vaccines;
— to develop challenge models in cattle
and badgers (in conjunction with colleagues in the Republic of
Ireland) and to use them to test those vaccines which show promise
in the small animal screens; and
— to develop and refine novel reagents
and tests for the diagnosis and control of TB.
21. A number of approaches to vaccine development
are being investigated, including BCG (the "gold standard"),
live attenuated vaccines (strains of M. bovis where a sequence
deletion prevents the bacterium from causing disease, but still
allows it to raise an immune response), killed whole mycobacterial
vaccines, subunit (proteins, peptides or DNA) vaccines and heterologous
prime-boost strategies.
22. 2002 has seen the completion of the
genome sequence of M. bovis in a collaborative project
between the Veterinary Laboratories Agency, the Institut Pasteur
(France) and the Wellcome Trust Sanger Institute (UK). This scientific
breakthrough was announced on 1 March 2002. This will provide
an invaluable research tool which will have a major impact on
our understanding of pathogenicity, evolution and epidemiology
of mycobacterial infection. One way in which this will help the
vaccine development programme will be to aid the development of
a differential diagnostic test for the diagnosis of M. bovis,
required in order to distinguish between infected and vaccinated
cattle. One approach has been to examine the deletions in M.
bovis BCG and develop candidates for a test for components
of M. bovis that are not contained in M. bovis BCG, M.
avium, or M. paratuberculosis. VLA are also using antigen
mining to develop pools or cocktails of antigens with the potential
for vaccine development.
23. Further aims of the projects to develop
diagnostic strategies for the detection of M. bovis in
badgers and cattle are:
— to understand and characterise the
underlying processes involved in M. bovis infection on
immunity and disease;
— to determine the effect of environmental
mycobacteria on the immune response to M. bovis;
— to investigate the induction of immunity
by vaccination; and to develop assays for the detection; and
— to develop assays for the detection
and quantification of M. bovis in animal tissues and excretions.
24. Several aspects of this work have the
potential to impact on other aspects of the Defra TB research
programme. For example, studies on immune responses of cattle
and badgers to M. bovis could underpin studies on transmission
and the natural history of the disease.
25. A sub-group of the ISG on cattle TB
has been established with a remit to "assist the ISG in advising
DEFRA Ministers on the feasibility for pursuing a TB vaccination
strategy for either cattle or wildlife. This should also include
consideration of future research requirements in addition to those
already in place". The sub-group is expected to report in
March 2003.
Other research to improve knowledge of the disease
and its transmission to and between cattle and other species
26. A new programme to investigate, both
experimentally and in the field, the pathogenesis of M. bovis
in cattle has been developed. The work is being carried out at
IAH, VLA and Queens University, Belfast. The investigators are
using an experimental infection model of cattle to address issues
regarding the kinetics and mechanisms of M. bovis transmission
and the relationship between transmission and immunological responsiveness.
These issues are of fundamental importance for the development
of effective vaccination strategies, and to investigate novel
diagnostics. The field studies involve detailed immunopathological
examination of naturally infected cattle, in order to further
understand the progress of the disease and evaluate current and
novel diagnostic tests.
27. The development of new methods of TB
diagnosis is closely integrated into the vaccine research programme,
because (i) diagnosis of TB will be an important parameter in
measuring vaccine efficacy, and (ii) new vaccine technologies
may compromise existing diagnostic techniques.
28. The use of a commercial blood test,
the gamma interferon ((IFN) test for cattle with improved defined
M. bovis specific antigens is being investigated.
29. Although in general the effect of FMD
on the research programme has been negative, it has presented
a unique opportunity to study factors affecting incidence of new
cases of bovine TB in herds restocked since the FMD out-break.
A new field study has recently started.
30. Two projects looking at potential wildlife
reservoirs of bovine TB other than badgers are in progress at
Central Science Laboratory and Oxford University.
31. Epidemiological studies of TB in the
badger are being carried out at several field sites and ecological
studies include novel methods of measuring badger density and
the perturbation effects of culling. Previous and new data from
the TB research programme is being used in several mathematical
modelling projects and a satellite imagery project to predict
the pattern of disease and the effect of control policies. Novel
molecular typing methods to differentiate strains of M. bovis
are being used in an integrated collaborative epidemiological
study aimed at elucidating the spread of disease in cattle and
wildlife over time.
Continued regular testing of cattle herds for
TB and slaughter of suspect animals, and where possible strengthening
of these controls
32. Following the suspension of testing
during the FMD epidemic for disease control reasons, at the end
of January 2002 there was a backlog of some 27,000 overdue bovine
TB herds tests. Approximately one quarter of cattle herds in GB
were affected, and many of these tests were more than a year overdue.
When testing was restarted it was targeted to those herds which
a veterinary risk assessment had identified as presenting the
greatest risk to human health, such as herds producing raw milk
for direct consumption or for use in raw milk products and those
herds which had the greatest risk of infection with bovine TB.
By the end of December 2002 the backlog had been reduced to just
over 9,000 overdue tests. This reduction has required a significantly
raised effort from both the SVS and LVIs.
33. Confirmation of disease in animals that
react to the TB test dictates how the incident is further managed.
Unconfirmed breakdowns are not as strictly controlled as those
which are confirmed, where the herd must undergo two short interval
(60 day) tests in order to have movement restrictions removed.
Confirmation of disease is by detection of typical lesions of
tuberculosis on post-mortem examination and/or by culture of M.
bovis in tissue specimens, which usually takes about six weeks.
Increased numbers of post mortem samples submitted to the Veterinary
Laboratories Agency in 2002 from the higher numbers of animals
involved in TB incidents has led to a shortfall in the capacity
of the laboratory to culture and confirm M. bovis in samples
submitted by the SVS. This has led to delays in confirmation of
disease status in tuberculin test reactors with no visible lesions
(NVL) on post mortem examination. In some herds with NVL reactors
only, this has resulted in extended movement restrictions.
34. This problem is being addressed through
increasing laboratory capacity and taking a risk based approach
to the need for maintaining restrictions in certain circumstances.
Ways of streamlining and automating certain parts of the culture
process and novel methods of confirmation are being investigated.
A reduction in the volume of samples going for analysis has been
brought about by reducing the volume of samples going from herds
with reactor animals and visible lesions on slaughter, with a
concomitant lessening of overall epidemiological data that would
otherwise have been available.
A badger culling trial to test the effectiveness
of badger culling in reducing TB in cattle
35. Initial proactive culls have been completed
in all 10 triplets which are now operative. Following FMD, Defra's
Wildlife Unit (WLU) met the programme for resuming trial operations
agreed with ISG.
36. Badger culling fieldwork was suspended
from 23 February to 31 December 2001 due to foot and mouth disease.
The majority of staff of the Wildlife Unit (WLU) who carry out
the field work of the badger culling trial were redeployed to
assist in FMD control measures. Surveying operations re-commenced
in January 2002 and included intensive surveys of the final three
triplets. In order to deal rapidly with the backlog of work, contractors
were employed to undertake 3-year surveys in a further three established
triplets.
37. On 29 April 2002, Ministers announced
that trapping operations would recommence on 1 May (ie after the
closed season from 1 February to 30 April). Since that announcement,
proactive follow-up culls have been undertaken in seven triplets.
Reactive culling was also carried out in 2002 and the initial
proactive culls in the final three triplets were completed.
38. In March 2002 the ISG submitted a report
to Defra on the effects of FMD on the field trial. This report
was forwarded to the Committee via Deirdre Kennedy's letter of
12 June 2002 to Gavin Devine. The ISG is currently updating this
assessment and is expected to report to Defra Ministers in March.
It is expected that particular attention will be paid to reviewing
the implementation of the reactive strategy given the large numbers
of TB breakdowns following FMD.
STATISTICS ON
BOVINE TB
39. Before the FMD epidemic, statistics
on TB were published monthly on the Defra website. The monthly
statistics on herds and animals tested under the testing programmes
and control measures met the quality criteria for "national
statistics". However, the atypical testing patterns seen
between late February and early December 2001 and the subsequent
biases introduced by the targeting of testing to high risk herds
in the drive to reduce the backlog has produced figures that are
not yet of a sufficient quality to regain that status. It is hoped
that Defra statistics on TB will once again be able to meet the
quality criteria for "national statistics" in summer
2003 when the TB testing backlog has been cleared.
40. National statistics are, by their nature,
published sometime after events to allow for quality controls.
Defra statistics on TB therefore usually reflect the situation
three to four months before the date of publication. In the aftermath
of FMD there was a pressing need for more immediate information
on progress with reducing the backlog and on the greater numbers
of TB incidents being found on resumption of targeted testing.
In response to industry and stakeholder requests, Defra has shared
with TB Forum members monthly summaries of raw data from the SVS
work management computer system (VetNet). The data held on this
system is also used as the raw data for TB statistics, but it
is by nature of a lower order of reliability than national statistics.
The description of the latest situation set out below is based
on information taken directly from VetNet. It should be recognised
that there are some limitations to the accuracy of this data.
As further information is entered on the VetNet system and data
quality checks are carried out over the next few months these
figures are likely to change. However, they give a broad indications
of trends.
41. VetNet data for the period January to
December 2002 show that of some 100,000 herds in Great Britain
just over 43,500 herds were tested. During the same period, just
over 4,000 herds were under movement restrictions at some time.
Of these just under 3,200 herds suffered a new TB incident in
2002, of which just under 1,700 have so far been confirmed (although
the number of confirmed breakdowns will rise as the results from
post mortem cultures come through). During 2002, some 19,500 cattle
were slaughtered with compensation.
THE EFFECT
OF THE
FMD EPIDEMIC ON
THE INCIDENCE
OF BOVINE
TB
42. During the 10 years before the FMD epidemic,
the number of TB breakdowns had been rising by approximately 20%
each year. There has been a further significant increase in the
numbers of herds and the numbers of individual animals affected
with cattle TB during 2002 when compared with 2000. Comparisons
with 2001 are not informative because of the suspension of testing
during the FMD epidemic.
43. In order to draw any conclusions on
the validity of a comparison between the full year of testing
carried out in 2000 and 2002, account must be taken of the additional
testing carried out during 2002 in order to deal with the backlog
of tests which had built up during the FMD epidemic. Raw data
show that during 2002 a total of 43,567 herds were tested compared
with 35,610 during 2000. However it is clear that the numbers
of incidents have not fallen and that, in those herds where there
are TB incidents, more cattle that react to the TB test are being
found, suggesting an increase in within herd spread. It is likely
that delays in the detection and removal of reactors have contributed
significantly to this.
44. Out of around 1,870 herds reformed after
FMD culling and tested for bovine TB by the end of August 2002,
some 105 have had TB incidents, both confirmed and unconfirmed.
This represents about 6% of reformed herds tested by that date.
Early in 2002 movement restrictions were placed on 866 herds with
overdue 6 and 12 month tests as a veterinary risk assessment had
shown these to be at particular risk of infection with TB. By
the end of August 2002 27% of those herds tested had been found
to have cattle that reacted to the skin test.
45. Statisticians within Defra and the ISG
advise that until the distortion introduced by the testing backlog
is reduced further it is too early to try to draw any conclusions,
particularly about whether or not there has been a step change
in the rate of increase in the number of herd incidents. It is
unlikely that an assessment can be made until the middle of 2003.
46. A table setting out key raw data for
the years 2002 and 2000 is attached at Annex C.
10 February 2003
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