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The existing skin and blood teststest
See www.bovinetb.co.uk/forum_topic.php?thread_id=46&page=1 and www.bovinetb.co.uk/article.php?article_id=56 for information on the infamous Boxster case. This case has set a legal precedent and it means that any cattle owner who believes that the tests for bTB have not been undertaken properly can challenge through the courts. The Judge did not accept Defra's expert's argument and came to the conclusion that a test not taken according to the rules is invalid. This sets a legal precedent. Any test not taken according to the rules can now be challenged.... Any farmer who has a problem with bTB tests that were not done according to protocol can scuttle off to court and use Boxster's precendent...Of course a farmer can have a sound legal challenge with a such a test. DEFRA were so desperate not to set a precedent..... instead they have created a dirty great big one.

Anergy



 Added by  becky
 10 Apr 2013, 6:45 PM


Email from JB dated 7 April 2013 makes some interesting points about anergy. The information is reproduced below.
 
“Anergy is a term in immunobiology that describes a lack of reaction by the body’s defense mechanisms to foreign substances, and consists of a direct induction of peripheral lymphocyte tolerance.” – Wikipedia
 
Or in simple terms, the body does not produce a reaction to pathogens.  Effectively, the cells in the body responsible for recognising pathogens, don’t.  Where is all this leading?
 
Well, it’s like this. The skin test works by testing for the mild reaction to tb within the needles.  If a cow’s lymphocytes recognise the bacterium, they will go into defence mode, and a reaction shows on the surface of the skin.  Thereby showing that the cow has already been in contact with the disease, it is then termed a ‘reactor’ and must be destroyed.  If the cow is anergic, it will not react to the bacterium. Even if it has tb.
 
If a cow can take 11 (yes 11) tb skin tests, and pass as negative, thus going on to infect her calves over a period spanning 5 years (2003-2008) before the gamma interferon test picks up that she has tb (shown here; TB Anergic Cow With Tuberculin Mastitis)…..could this not have something to do with the mystery herd breakdowns currently being attributed to badgers?
 
Not only that, but it’s not just one cow…..
 
“A severe outbreak of bovine tuberculosis in a 1300-head, multi-site dairy herd in Great Britain had several unusual features, includinganergy to the tuberculin skin test, milkborne disease in calvesand a farm cat, and a risk of human infection. The outbreakwas controlled by culling 221 cattle over 15 months, by usingthe -interferon (-IFN) test and by the examination of milk samples.The -IFN test detected infected animals that were not detectedby the skin test.”  The Veterinary Record 163:357-361 (2008).
 
But that’s still not all…apparently cows can become anergic at certain times, namely when giving birth, due to a reduction in their immune response.
 
“It has long been known that early and late cattle TB cases are the usual cause of recrudescence in herds supposedly tested as clear of the disease. A study some twenty years ago claimed that some 0.30 of cows go temporarily anergic or non-reactor after parturition. Pregnancy certainly modifies the immune response, allowing a proliferation of lesions, followed by their regression post-partum. Young heifers may carry latent TB until their first pregnancy activates the disease (Francis 1947). And so seemingly, a significant minority become permanently anergic yet active TB spreaders (Blood 1989). In fact three such anergic cases caused some 18 herd breakdowns in one parish in the West Penwith or Lands End area of Cornwall (Richards 1972).”  M Hancox The Great Badger and Bovine Tb Debate
So what does this mean?
 
To me, it means that the skin test is not effective enough. It means that cattle that have tested negative, may be positive, and when there seems to be no reason at all for a herd breakdown, except the local badgers, in fact, there could be a cow with tb, or could have been a cow with tb, now sold on to pass the bacterium on somewhere else.
 
Not only that, but I also discovered today that tb can be passed in water, downstream perhaps? And since a cow can pass  38 million bacilli/day in their faeces, that’s a lot of potential baccilli passing into the local stream. How do we know that this isn’t causing outbreaks?
 
Anergy, how is it that this is such a little known concept in the tb debate?

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