APPENDIX 29
Supplementary memorandum submitted by
Helen Fullerton Ph D, Farming and Livestock Concern UK (P28A)
The Independent Scientific Group and DEFRA's
spoligo-typing team have incontrovertibly identified cattle-to-cattle
transmission as the cause of TB spread, and DEFRA's splendid new
policy (TBF79) on stringent testing and movement restriction will
halt the devastating escalation of TB.
The missing link in DEFRA's policy is a failure
to identify the cause of TB persistence in the hot spot areas
and thus to eradicate TB from the UK. I propose that the cause
of the persistence is the "silent carrier" whose effect
has been seriously underestimated. Silent carriers are chronically
anergic cattle whose immune systems are so suppressed they never
respond to the tuberculin test (false negatives).
A silent carrier can carry the infection for
years and remain healthy, with the bacilli persisting in bacteriostatic
association within the macrophages of the host. The reason for
the decline in TB in the mid-seventies to mid-eighties was the
selling off of thousands of older cows to make way for the influx
of Holsteins, thereby temporarily removing silent carriers.
Researchers advise that chronic anergy is induced
by prolonged stress, secondary infection, parasites or zinc deficiency.
Biochemical evidence suggests it is also induced by selenium and
cobalt (B12) deficiency. These three elements, zinc, selenium
and cobalt, as well as copper and iodine, are intrinsically deficient
in soils developed on limestone, red sandstone and granite, the
geological locations of the hot spots and of the areas to which
the disease is most easily spread.
As I have proposed in my submissions, the crucial
factor is not exposure but susceptibility. Resistance can be induced
by raising cattle intake of the trace elements on which immuno-protection
depends, preferably by restoring them to the depleted soils, so
that they get them in their forage and feed.
I suggest that pilot trials should target the
hot spot areas with a view to identifying and eradicating the
silent carriers, and that this can be achieved by reactivating
their immune systems with an optimum intake of zinc, selenium
and cobalt, together with husbandry measures eliminating stress.
In addition to giving the trial herds immuno-protection,
there are two possible outcomes for the silent carrier:
1. her immune system will be activated enough
for the cow to respond to the tuberculin test, identified and
slaughtered. Tests in the pilot areas could be at three-monthly
intervals;
2. her immune system will be sufficiently
activated for the cow's cytotoxic T-cells to break the bacteriostatic
mechanism and destroy the pathogen. She will now react as an immune
animal.
27 February 2003
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