Dec 2003: Column 218W
Mr. Paterson: To ask the Secretary of State for Environment, Food and Rural Affairs what plans she has to replace the TB skin test used on cattle as a preliminary diagnostic aid with a more accurate and sensitive test. 
Mr. Bradshaw: Improved diagnosis of TB in cattle is a major objective of Defra's wide-ranging research programme. The current most promising candidate is the gamma interferon test, a laboratory-based blood test that measures the immune response to M. bovis (the causative agent for bovine TB) of T-cells in cattle blood.
This test was officially recognised by the EU in July 2002, but only for use as a supplement to the Single Intradermal Comparative Cervical Test (SICCT) in TB affected herds. The test is considered more sensitive than the SICCT, but less specific, meaning that it results in a higher probability of false positives. For this reason, the gamma interferon test cannot be used on its own as a screening test for TB for the time being.
So, a supplementary test with a higher probability of delivering false positives, but are Defra correct in informing their ministers and the public that gammaIFN will detect Tb at an 'earlier stage'. No. From answers to written parliamentary questions, they are not.
23rd March 2004: Column 689W
Mr. Paterson: To ask the Secretary of State for Environment, Food and Rural Affairs how long after exposure to an infective dose of M.Bovis bacilli a bovine animal becomes infectious, and what the typical duration of infectivity is 
Mr. Bradshaw: Published figures for the time from exposure to being infectious include 87 - 226 days after natural exposure in a United Kingdom study.[ ] The typical duration of infectivity is not known.
Now we are sure you don't need reminding that Tony Yewdall's cattle waited in limbo for at least six months before slaughter, as did those of the Somerset based Burrough Farm Partnership. And we have discussed before the latency of the skin test as being a published 30 - 50days from exposure to flagging up an immune response to a bovine tuberculin antigen jab. (Gamma has a latency of approx 28 days) The maximum exposure window for these cattle, could have been that length of time before the previous skin test which may have been at 60 days, six months, a year or several years, depending on herd and parish disease status.
Only 7 of 177 cattle slaughtered after gamma bloods had visible signs of Tb. And those were not necessarily at an infectious stage. How long had they been waiting? The thick end of eight months - or 240 days from the latest possible exposure. And how long did PQs tell us was the maximum time of an animal becoming infectious after natural exposure? Yup, you read it correctly. A range " 87 - 226 days ".
So we repeat - as does our big sister site, what an appalling, absolutely avoidable waste.