BADGERS AND BOVINE TB

by Martin Hancox, BSc and BSc Hons Natal BA and MA Oxon

Three key misunderstandings

Darwin’s Bulldog, T.H. Huxley:-
“The great tragedy of science, the slaying of a beautiful hypothesis by an ugly fact.”

Darwin C:-
“False facts are highly injurious to the progress of science, for they often endure long.” … “The blindness of preconceived opinion.”…

Some long forgotten "True Facts":-

Bang 1892:-
It is found that the tuberculin-test is no more perfect than are other things in this world. Sometimes it fails. Animals with a very real degree of tuberculosis will sometimes fail to react, and the same applies to animals with a very slight degree of the disease. Further, a positive reaction has been observed several times in animals in which no tuberculous changes were found on examination of the organs when the animals were slaughtered … but it would be the greatest folly to reject this method because it is not able to give everything we desire.

Francis 1947:-
“It is known that the primary focus in cattle may remain latent for many years or at the most progress very slightly (Bang 1899, M’Fadyean 1899)…but the lesions remain ‘open’ …if any animal reacting to the tuberculin test, even with very slight lung lesions, is left in a herd spread will be more or less rapid.”

Blood’s Veterinary Medicine 1989:-
“If the incidence of reactors is high at the first test or if ‘open’ lesions are found in culled animals, emphasis must be placed on repeat testing at short intervals or the spread of the disease may overtake the culling rate.”

“…no reliable test to detect the poorly sensitized animals in the early or late stages of the disease which ARE THE USUAL cause of recrudescence in herds that have been classified as being free of the disease.”

"And there is nothing new under the face of the sun" ... the classic quotes above ... The rationale for badger culls is based on

THREE main claims BUT these are in fact injurious "False Facts", which have indeed persisted long... even though two were very clearly understood a century ago !! THUS :-

1.Cattle are not the infectious source of TB to other cattle or badgers (Zuckerman p.86, 94; Dunnet para 60);

2.TB appears in new or repeat breakdown herds where there is no obvious source of cattleTB;

3.Badger culls "work" or make things worse .. perturbation. By a bizarre leap of faith if you remove 50 out of 100 TB cows from population X... the drop of 50% is due to removing the cows, but having decided badgers are the main source it is claimed the cull has worked!!.... and in none of the so-called proof cases were there anywhere near enough TB badgers involved (see section 6 (2), and 8(3) b & c.)

A. Routine SKIN TESTS MAY FAIL to detect small incidents; and to remove ALL cases in large incidents (and the bigger the herd the more likely to be missed cases so chronic infection). Since the test is only 80% accurate (sensitivity), if the incident is only of 1-2 cases /breakdown, tests may miss up to 20% of such herds (at the low point in GB and both Irelands c. 50% of breakdowns were "singletons"). Similarly, in Scotland only premovement tests could find only 16 in 20 imports, but with postmovement tests too this finds 19 out of 20 carriers (Smith L p.58.)

IF there are 6 - 40 reactors at the disclosing test then there is a 4 or 9% chance of an infected animal being left in the herd after 2 clear tests .. hence 1999, in the subsequent 6 mnth check test with herds of 100/101-200/200 plus cattle, recurrent incidents occurred in 6.9/10.4/14.2% of incidents (Goodchild 2001).Comparably, the IFN Trials found repeat breakdowns after 14 mnths months in between 25 and 31% of herds (ISG p.239). It has been long recognised that repeat skin tests may only be 65% accurate, hence missing 1 in 3 cases...ie THIS 30%. So, the bigger the herd and the more severe the breakdown ie the period left untested, permitting within herd spread :- the greater the chance of repeat breakdowns .. as with sadly many big dairy herds under restriction still since FMD 2001. Clearly repeat breakdowns in chronically infected herds can be either that new early cases take time to "rise to the surface", with intermittent appearance months/years later ... OR much worse, where total non-reactor or ANERGIC late TB cases arise, big herds may never go clear until the culprit dies or is culled due to lameness, mastitis, infertility (c. 250,000 cows /a).See section 2 hidden TB.

B. UNCONFIRMED CASES...It gradually became accepted "wisdom" in the early 1990s that reactor herds "without lesions "were re-named UNConfirmed ... and rather foolishly ignored as a reservoir of TB . BUT this mistake was noted variously, Dunnet para 38 over 80% actually TB plus, Wilesmith 1987 c. 70% . Under EC Directive 64/432 ALL REACTORS should be considered to have TB, even though over 20 years REACTORS were only confirmed in 40% of skin test cases /18% of IFN cases, and new confirmed HERDS ranged between 15 and 64% in 1994/2001. SO this HUGE reservoir of cattle TB circulating below the radar has been there all along...With up to 85% of herds "officially" UNConfirmed...THERE is your 90% "DUE to Badgers !!" Since the specificity of the skin test is 99.99%... that means only 1 in 1000 may be true false positives ie. do not have TB (Smith L, p.65, 72).

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