Memorandum submitted by the National Farmers'
Union
BOVINE TB
EXECUTIVE SUMMARY
1. The incidence of bovine tuberculosis
continues to increase despite the presence of statutory controls
and the imposition of a routine cattle testing and culling programme
over a very long period of time. We are further from eradication
now than we were in the 1970s.
2. The NFU sees two fundamental reasons
for this failure in dealing with the problem. First, a known wildlife
reservoir of M (Mycobacterium) bovis—the badger population—is
left untouched while enormous expense and effort are devoted to
trying to keep the infection down in cattle. Irish work on the
role of badgers in the epidemiology of the disease should be referred
to here. Second, that there is no way of preventing cattle from
being vulnerable to the infection that is around them, whether
that be in other cattle, in wildlife, or simply in the environment.
3. The solutions may be obvious, but we
know that they are not simple. In the short term there must be
measures to address the incidence of M.bovis in the badger reservoir,
and we have set out strategies for doing this on many occasions
in the past. In the longer term the development of vaccines to
protect cattle herds is probably the only realistic route to eradication.
PRELUDE
4. It is this latter, scientific, aspect—in
the main—that the present Inquiry addresses. We must stress
yet again however that we believe bovine tuberculosis to be multi-factorial
in its aetiology, and that the approach to dealing with the disease
must recognise this. The fundamental need for a control/eradication
programme is re-emphasised. While the original purpose of public
health protection is largely achieved, the fall-out from this
is being increasingly felt by cattle farmers to the extent that
many are going out of business, and many more suffering crippling
financial, social and psychological damage. Add to this the growing
disquiet that a major element in the Governments projected Animal
Health and Welfare Strategy (AHWS) is manifestly failing to achieve
its aims, and the need for urgent solutions is underlined.
VACCINATION
5. We have been told for a decade or more
that a TB vaccine for use in cattle is between five and 10 years
away, and this is apparently still the case. The NFU is not qualified
to comment on or judge in scientific terms the progress, or lack
of progress, in this direction, but the worsening disease situation
clearly calls for a redoubling of effort.
6. It is not clear to us whether material
resources are the stumbling block here, or whether it is an "intellectual"
breakthrough that is needed. We understand that the likelihood
that current work on new human vaccines will be transferable is
remote, but that genomics could help generate candidate vaccines
that would protect cattle better than BCG. Increased resources
and fast track approval procedures should be sought to hasten
the developmental process.
7. The development of BCG for use in badgers
seems to pose different problems. Even with a proven effective
product one of the main obstacles to its introduction would be
the problem of delivery. On-going work in Ireland suggests a greater
potential for BCG in badgers than in cattle, but its realisation
would depend on at least two factors. First, that badgers are
indeed a major source of infection for cattle; and second, that
maximum effective uptake at optimum dose rates can be guaranteed.
We would like to see regularly published information on progress
in this area, and guidance as to its potential application under
field conditions in infected areas in England and Wales.
8. While the disease situation calls for
urgent short and medium term measures to bring the level of infection
under control, the ultimate aim still has to be eradication. It
is clear to us from discussions with scientists involved in research
in this area that a successful vaccination policy is the only
sure way of achieving this. We can only concur with the recommendation
of the Independent Scientific Group Vaccine Scoping Sub-Committee
that "it will be imperative to maintain the current effort
on development and testing of vaccines" and that "the
well developed and effective international collaborations with
scientists working on vaccines for both animal and human TB must
be maintained and built on".
DIAGNOSTICS
9. Another critical aspect of any genuine
attempt at a control/eradication strategy is the accuracy of diagnosis.
A greater efficiency in routine clinical diagnosis would give
greater purpose and precision to the cattle cull. The standard
comparative intra-dermal skin test is very good on a herd basis,
but not particularly useful as an individual animal screen. Again,
we understand that post genomic studies could help in the development
of a more effective method. In the meantime the wider employment
of gamma-interferon could be approved to supplement the tuberculin
test. The Veterinary Laboratories Agency must continue to improve
the test by using different and more specific antigens; this could
significantly increase its usefulness both as a screening tool,
and as a pre-movement test.
10. To complement the development of a cattle
vaccine for widespread use there must be a properly validated
test available to distinguish a vaccinated animal from one exposed
to natural TB infection. Improved genomics could help here in
differentiating between M.bovis and BCG (or equivalent) genomes.
11. Developments in these areas clearly
depend on the continuing availability of resources to carry them
through to a conclusion.
IMMUNITY/RESISTANCE
12. There are still a number of questions
unanswered in relation to susceptibility and resistance among
animals of the same group, or between groups of animals. Why,
for example, do certain animals in a herd succumb to the disease
and not others, and why do some herds in a heavily infected area
remain clear? Resistance to infection may indeed be related in
particular cases to levels of trace elements such as selenium—and
there are those who suggest that it is—and attempts should
be made to establish the significance of this one way or another.
13. A related question is why some animals
respond to the comparative test but do not show pathological signs?
The NFU is not in a position to attempt to answer these questions,
but we can emphasise the importance of knowing more about the
basis of resistance (or perhaps immunity) to M.bovis.
POSTSCRIPT
14. The particular areas being addressed
by this Inquiry offer the possibility of long-term solutions to
a very serious disease presence that also requires urgent, short
term, attention. We therefore repeat our concern that current
measures to reduce infection in the cattle population are mirrored
by strategies to deal with the wildlife reservoir of M. bovis.
It does not seem logical or sensible to address the problem in
one affected species and not in another that lives in close proximity
to it. It is important that evidence from current Irish work is
examined as part of any decision on the value of culling as a
basis for moving forward on this issue.
15. The development of longer-term measures
is also of course an integral part of the eradication process.
We made the point above that success will only be achieved by
application of a series of interlinked strategic elements. These
must include—as well as selective cattle and badger culling—better
diagnostic methods, vaccination of cattle and/or badgers, and
on-farm bio-security preferably built in to a specific health
plan.
16. It is important to regard bovine tuberculosis
and the means of combating it as part of the evolving Government
Animal Health and Welfare Strategy. It is inevitable that the
success of the two strategies will be seen as closely linked.
National Farmers' Union
May 2004
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