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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.

bTB testing under scrutiny



 Added by  Trevor
 31 Oct 2011, 9:25 AM


http://www.cardiff.ac.uk/news/articles/bovine-tb-testing-under-scrutiny-7546.html
 
Interesting research by Dr Gareth Enticott of Cardiff University discusses the proposal to introduce competitive tendering for TB testing contracts in parts of England.
 
He says, “Planned changes to the way vets are allowed to conduct TB tests could have a dramatic impact on rural veterinary practices and fail to address quality control issues surrounding tests for bovine tuberculosis..."
 
How many farmers have any confidence in the existing, flawed testing regime?
becky
EUROPE A report of a technical meeting of the EFSA Scientific Network for Risk assessment in Animal Health and Welfare - Bovine Tuberculosis Testing
Parma held 21 February 20121 can be found at: http://www.efsa.europa.eu/en/efsajournal/doc/288e.pdf
 
Included is the bTB status for several EU countries, including the UK, The Netherlands, Poland, Germany, Spain, Ireland, France, Hungary, Italy and Belgium .
 
SUMMARY
The Animal Health and Animal Welfare (AHAW) scientific network was created in 2009 with the aim to facilitate scientific cooperation in the field of the EFSA’s mission by coordinating activities, exchanging information, developing and implementing joint projects, exchanging expertise and best practices. During the AHAW scientific network meeting, in November 2011, the subject of bovine tuberculosis (TB) and in particular diagnostic testing for the purpose of disease control and
demonstration of freedom was identified as of common interest. A technical meeting was organised with the objective of sharing information about bovine TB and bovine TB testing data and to assist
EFSA in collecting information relevant to future mandates.
 
Representatives from 10 Member States participated in the meeting. Based on the experts presentations a summary of the information
concerning the official status on Bovine TB infection of each country and bovine TB testing and surveillance was made. There is large variation on the test and testing protocols used in different MS. These variations refer to the use of both the official bovine TB diagnostic test (tuberculin skin tests) and the ancillary test (IFN-γ BA test) but also and more important on the objectives to achieve. These variations can affect the diagnostic tests accuracy. The different tests and testing protocols are not
adequately described resulting in surveillance data that are difficult to validate and compare. The meeting provided an overview of the issues on the disease surveillance and control and gave the opportunity to identify areas of future collaboration.
 
becky
The Control of Bovine Tuberculosis in Northern Ireland
This report, Northern Ireland Audit Office, was published in 2009 but contains some very interesting information about the 'imperfect' skin test, revealing many incidents when it was not carried out properly.
 
Bovine TB testing procedures (Part 2 of the Report)
 
• the limitations of the Bovine TB Skin Test in detecting infected animals
• the cost of testing carried out by Private Veterinary Practitioners (PVPs)
• the quality of work being carried out by a number of PVPs • Departmental supervision of PVP testing
• disciplinary action against PVPs who breach procedures
 
Compensation, enforcement and tackling fraud (Part 5 of the Report)
 
• the cost of compensation
• compensation valuations
• enforcement of the legislation
• tackling fraud.
 
http://www.niauditoffice.gov.uk/a-to-z.htm/report_archive_2009_bovinetb

 
becky (Guest)
Farmers Weekly in February (www.fwi.co.uk/articles/05/02/2013/137488/tb-skin-test-questioned-after-false-results.htm#.URD1fq2kidE) reported on the following case. Interestingly several farmers have told us similar stories.
 
The accuracy of the bovine TB skin test has been questioned after a cow that tested negative for five years was found to be riddled with the disease. The cow was part of the Gelli Aur College Farm in Carmarthenshire, which has been under TB restrictions since 2007 and lost 300 cattle to the disease.
 
Interesting, back in 2009 here is a report about bTB at Geli Aur - you can draw your own conclusions!
 
TB devastates Welsh College's dairy performance
Robert Davies
Monday 19 January 2009 06:11
 
Bovine TB has had a devastating impact on milk production and profitability at Gelli Aur College in Carmarthenshire.
More than 250 cattle have been culled over the past 18 months, including 100 following a single test and farm manager John Owen admits the outbreak has also sapped staff morale.
 
He says it does not help when nothing is being done about possible wildlife reservoirs of infection, including a large number of badger setts and wild deer. But he is reluctant to take up the suggestion that the Gamma Interferon test should be used to pinpoint all infected cattle on the farm.
 
"We do not want to lose a large number of animals in one go as we want to maintain cash flow, have cows for teaching students and hang on to our quality staff."
 
The latest figures show that TB has hit the low input spring calving herd most severely. In December it numbered only 86 cows, 42% fewer than in the same month in 2007 and well below the planned total of 180.
The culling rate was 74% in the year to July 2008 and herd milk production declined by 7% to 660,000 litres. Overall the herd lost £42,161, or 6.4p/litre, excluding compensation for cattle culled because of bTB.
 
Six months later the £133,690 rolling herd margin over purchased feeds was 19% lower than in December 2007, though a higher average milk price had increased rolling margin/litre from 18.41p to 20.86p.
Mr Owen believes the average £1250 a head valuation of culled spring calving stock just about covers the cost of replacements, though sourcing clean cattle is proving difficult.
 
Farm manager John Owen said the level of infection in the fifth-lactation animal only came to light when it was slaughtered.
 
"We culled her at the end of her productive life and at slaughter she was found to be riddled with TB," said Mr Owen. "The level of infection in that cow suggests she had been infected for years."
 
He is concerned that the homebred cow may have been at the root of successive test failures.
 
"The cow kept passing the test, there was nothing to suggest that she was infected," he said. "It is a concern that she may have been spreading the disease to other animals within the herd."
 
The farm has just recorded its first clear test and will have its next test later this month. "We are keeping our fingers crossed that we will get the all-clear," said Mr Owen.
 
He admitted that six years of movement restrictions had affected the farm business significantly and had pushed the stocking rate to its upper limit.
 
becky
Estimation of the Relative Sensitivity of the Comparative Tuberculin Skin Test in Tuberculous Cattle Herds Subjected to Depopulation, report published 2012, which can be read in full at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0043217
 
Abstract
Bovine tuberculosis (bTB) is one of the most serious economic animal health problems affecting the cattle industry in Great Britain (GB), with incidence in cattle herds increasing since the mid-1980s. The single intradermal comparative cervical tuberculin (SICCT) test is the primary screening test in the bTB surveillance and control programme in GB and Ireland. The sensitivity (ability to detect infected cattle) of this test is central to the efficacy of the current testing regime, but most previous studies that have estimated test sensitivity (relative to the number of slaughtered cattle with visible lesions [VL] and/or positive culture results) lacked post-mortem data for SICCT test-negative cattle. The slaughter of entire herds (“whole herd slaughters” or “depopulations”) that are infected by bTB are occasionally conducted in GB as a last-resort control measure to resolve intractable bTB herd breakdowns. These provide additional post-mortem data for SICCT test-negative cattle, allowing a rare opportunity to calculate the animal-level sensitivity of the test relative to the total number of SICCT test-positive and negative VL animals identified post-mortem (rSe). In this study, data were analysed from 16 whole herd slaughters (748 SICCT test-positive and 1031 SICCT test-negative cattle) conducted in GB between 1988 and 2010, using a Bayesian hierarchical model. The overall rSe estimate of the SICCT test at the severe interpretation was 85% (95% credible interval [CI]: 78–91%), and at standard interpretation was 81% (95% CI: 70–89%). These estimates are more robust than those previously reported in GB due to inclusion of post-mortem data from SICCT test-negative cattle.
 
becky
Testing for bovine TB carries huge health risks for those involved. In these times of such regular testing in some areas (every 60 days for herd breakdowns), the risks are increased, oarticularly as the skin test involves handling the cattle on two seperate occasions each time.
 
In April 2010 an Irish farmer died as a result of testing. In January of this year a dairy farmer was been killed by a bull as he tested cattle for TB on his Carmarthenshire farm.
 
The HSA (which can only deal with employees) has records/reports of some incidents but many incidents involving injury to farmers and testers are not reported.
 
The existing skin test policy is a greater risk to human health than the disease it is trying to eradicate.
 
becky
Prof Torgerson comments (12/4/13) - relative sensitivity is meaningless. You need absolute sensitivity. For this see:
http://www.omicsonline.org/2161-1068/2161-1068-2-120.pdf
 
becky
Estimation of the Relative Sensitivity of the Comparative Tuberculin Skin Test in Tuberculous Cattle Herds Subjected to Depopulation
Published August 2012
 
Abstract
 
Bovine tuberculosis (bTB) is one of the most serious economic animal health problems affecting the cattle industry in Great Britain (GB), with incidence in cattle herds increasing since the mid-1980s. The single intradermal comparative cervical tuberculin (SICCT) test is the primary screening test in the bTB surveillance and control programme in GB and Ireland. The sensitivity (ability to detect infected cattle) of this test is central to the efficacy of the current testing regime, but most previous studies that have estimated test sensitivity (relative to the number of slaughtered cattle with visible lesions [VL] and/or positive culture results) lacked post-mortem data for SICCT test-negative cattle. The slaughter of entire herds (“whole herd slaughters” or “depopulations”) that are infected by bTB are occasionally conducted in GB as a last-resort control measure to resolve intractable bTB herd breakdowns. These provide additional post-mortem data for SICCT test-negative cattle, allowing a rare opportunity to calculate the animal-level sensitivity of the test relative to the total number of SICCT test-positive and negative VL animals identified post-mortem (rSe). In this study, data were analysed from 16 whole herd slaughters (748 SICCT test-positive and 1031 SICCT test-negative cattle) conducted in GB between 1988 and 2010, using a Bayesian hierarchical model. The overall rSe estimate of the SICCT test at the severe interpretation was 85% (95% credible interval [CI]: 78–91%), and at standard interpretation was 81% (95% CI: 70–89%). These estimates are more robust than those previously reported in GB due to inclusion of post-mortem data from SICCT test-negative cattle.
 
www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0043217
 
becky
 

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