EXTRACT FROM THE VETERINARY RECORD
The following letter from J
Gallagher (South Devon) & R H Muirhead (Gloucester) was published in the VR on 3 July
1999
"We are currently experiencing
the worst outbreak of tuberculosis among our cattle herds for decades and it would be
sensible for determined action to be taken to control the problem. But is this being
done? Alas, a policy for control is on hold while the huge Krebs experiment to
determine 'the role of badgers in the spread of tuberculosis', scheduled to take at least
five years, is being started. So far, trapping, with only partial success, has been
carried out in one of the experimental areas in North Devon during December 1998.
Trapping is about to start in another two areas.
The casual observer might be
forgiven for thinking that TB in the badger must have only recently been found; but not
so. The first finding of tuberculosis in badgers was 28 years ago in 1971 (Muirhead
and others 1974). Since then a very considerable amount of research has been carried
out on TB in badgers and cattle.
Within a few years of the discovery,
sufficient data had been gathered to indicate that badgers were the likely origin of a
significant number of outbreaks of TB in cattle. To examine this hypothesis further,
MAFF veterinarians embarked on a pragmatic experiment in control and compared the TB
history of a large area of 104 km2 before and after complete removal of the badger
population. The results were dramatic. The area comprised just over 100 farms
with approximately 1,000 cattle in which a cyclical pattern of test reactors had been
observed with peaks at about three or four years. Removal of the badgers resulted in
a nil incidence of reactors which lasted 10 years through two or three expected cycles
(Clifton-Hadley and others 1995). After badgers were allowed to recolonise this
area, small numbers of reactors started recurring, mostly at the margins of the cleared
area.
Similar dramatic effects were
observed in a smaller scale clearance (12 km2) in South Dorset (Wilesmith and others 1982)
and a large clearance (62 km2) in Hartland, North Devon (Krebs 1997). In a much
larger clearance started in 1988 in Offaly, Ireland, of 600 km2 with a 100 km2 area where
badgers were left undisturbed, the TB situation in the removal areas has shown a marked
improvement over the control area (Eves 1999).
Aside from these test areas, there
is now considerable experience among the specialist MAFF veterinarians of the effects of
control of badgers on the occurrence of TB in cattle, over a 28-year period, by staff
whose daily task is the control this notifiable disease.
Sadly, this was all clearly set
aside. The minister of agriculture endorsed the Krebs Trial to set in motion yet
another clearance experiment bigger than all before. Could this reasonably be
construed as prevarication? There has now been three separate independent reviews of
the problems of TB in badgers and cattle: Zuckermann (1980), Dunnet and others (1986) and
Krebs (1997). All concurred that TB in badgers posed a significant source of
infective for cattle. The approach to the control of the problem has been the
sticking point. Dunnet and colleagues proposed minimalistic control of badgers,
culling only those using the fields or at most the area within the boundaries of farms
with outbreaks. The adoption of this policy over the last more than 10 years has
coincided with the inexorable rise in outbreaks of TB in cattle. Not only was
it ineffective but in some situations this approach may made the situation worse by
disrupting social groups of infected badgers (White & Harris 1995).
Ministers have the unenviable task
of deciding whether to accept 'expert opinion' from independent review groups,
all of which have been headed by non-veterinarians. MAFF staff are then given the
policy to implement as best they can. The currently adopted policy of
experimentation proposed in the Krebs Report seems unlikely to appease anyone - not least
the farmers whose farms are to be used as undisturbed control areas in the trials.
Farmers are well aware that an outbreak of TB with consequential losses is likely to cost
them £10,000 or more at a time when income is at an all-time low. While killing or
interfering with badgers without a licence is illegal, that may not stop it
happening. Outbreak compensation might rationally be built into the trial but, of
course, if given to those in the trial area, what should be given to this outside the
trial? The trials are claimed to be required to formulate a future control policy.
But this difficult to accept since of the three options of control being tested, two are
likely to be unacceptable; that is no action or complete elimination of badgers.
Aside from the trial proposals, the
Krebs Review had many useful recommendations, chief of which was to endorse development of
a cattle vaccine using genetic manipulation to enhance immunity and reduce the
hypersensitivity response. This is an area which shows promise and to which funds
should be channelled, ensuring close cooperation with New Zealand researchers who have
already made some progress (Buddie and others 1995).
While vaccination of cattle in areas
where badgers are endemically infected holds hope for the future, the current wave of
outbreaks continue unabated. A structured culling of badgers is essential in newly
infected areas now as well as in much of the known endemically infected areas. It is
to be hoped that common sense will prevail and further extension of the unpopular and
unnecessary Krebs trial will be stopped."
GAME, SETT & MATCH to Gallagher & Muirhead
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