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The Skin Test

 Added by  Sally
 3 Apr 2010, 7:55 PM
There is an interesting statement in 'Testing for Bovine Tuberculosis in California' by John H Kirk. The report is describing the skin test and warns 'be aware that in non-infected herds it is considered normal to have 1-5% false positives or reactions at the site not due to Bovine Tuberculosis, on a whole herd test. This response may be due to previous exposure to Avian Tuberculosis or the Johne’s Disease bacteria, another Mycobacterium disease.'
Scientists say they have made a breakthrough which could be a crucial step in the introduction of cattle TB vaccine programmes.
Researchers have developed two candidate skin tests for cattle which they say can distinguish between animals that are infected with bovine TB and those that have been vaccinated against the disease with the BCG vaccine.
At present, the vaccination of cattle against bovine TB is forbidden under international and EU law because it is not possible to distinguish between a Bacille Calmette-Guérin- (BCG) vaccinated and TB-infected cow.
See also: 5 ways to improve TB control in the UK
The next stage is to evaluate these tests in field trials to a level conforming to World Organisation for Animal Health (OIE) standards. If all goes well, the test could be available to use in five years – depending on the appetite for policy makers to use the test.
Further, regulatory issues including demonstrating their safety and effectiveness will also have to be addressed before the diagnostic tools can be allowed to be used as part of TB eradication programmes. Such studies are already under way in the UK and India.
The tests have been established by teams headed by Professor Glyn Hewinson and Professor Martin Vordermeier, of Aberystwyth University, while working at the government’s Animal and Plant Health Agency.
They were created by an international team of scientists from Ethiopia, India, the Netherlands, United Kingdom and USA.
APHA grants access to new highly sensitive,specific test for chronic TB breakdowns
A new highly sensitive and specific blood test for bovine TB, Actiphage, has been accepted for exceptional private use in England, according to an Animal and Plant Health Agency (APHA) protocol published on 8th May 2018. Dr Berwyn Clarke, CEO of PBD Biotech, which has developed the bacteriophage ...
Henry Andrews set about building up his closed herd of pedigree Devon and cross breed cattle four years ago, but since November last year has been locked in a gruelling battle with the disease.
The herd, which he planned to increase to 75 next year, is now down to 37 head.
“I fear for my family’s future,” said Mr Andrews, whose wife has just given birth to their second child.
“I am frightened because if I have a repeat of the last test I will be finished as a suckler cow producer, with pretty much immediate effect and facing bankruptcy.”
The nightmare unfolded when six in-calf heifers tested positive on a routine skin test and were immediately destroyed on-farm in Pyworthy, Devon. Just weeks later, another 10 animals tested positive on the blood test.
With the 29-year-old waiting nervously for 28 additional cows to be retested, he called into question Defra’s entire bTB policy, including the badger cull.
“I have a closed herd, I have no nose-to-nose contact with other cattle from different holdings and I have a high level of biosecurity, with all visitors having to disinfect themselves and their transport upon entering the farm,” said Mr Andrews, who has also acted as a marksman on the badger cull in the high risk area for the last three years.
“I draw the conclusion that I either brought on infected cattle which had eluded a pre-movement test and subsequent testing, or the cull has displaced infected badgers onto my holding.”
The farmer, who has been in written correspondence with Defra Secretary Michael Gove, highlighted a Royal Society report which found the skin test could be between 49-74 per cent unreliable.
Makers of new test for TB in cattle win top dairy innovation award
Dr Berwyn Clarke, chief executive of PBD Biotech at Thurston, near Bury St Edmunds, was presented with the Royal Dairy Innovation Award 2019.
The Royal Dairy Innovation trophy and certificate are awarded for research and development in the field of dairy farming, with the award going to the most practical, relevant product which is likely to be the most significant innovation for the future of dairying.
It’s hoped PBD’s Actiphage test, which the firm says offers a fast and accurate way to detect the presence of bovine TB, Johne’s disease and other mycobacterial infections, will revolutionise livestock disease management as well as expediting food safety checks on milk and dairy products.
The Actiphage test, which delivers results within six hours, was originally developed as a tool for diagnosis of human TB.
The biotech firm has optimised and developed it to provide enhanced sensitivity and enable it to be used in blood or milk samples.
“Globally there is growing concern regarding the presence of live mycobacteria in milk that may have human health implications. This prestigious award is recognition of the opportunity this technology provides to ensure dairy products are free from these organisms as part of routine dairy quality control,” said Dr Clarke.
“We are seeing significant interest from dairy organisations throughout the world in Actiphage, and this award will significantly aid in transferring our technology into those global markets.”
Info from: https://www.eadt.co.uk/business/farming/pbd-biotech-scoops-dairy-tech-innovation-award-1-5883743?fbclid=IwAR2Vr3ZhMnCcD246mgp0hE...

Predict and prevent rather than test and treat says chief guest speaker Richard Sibley, a vet from Devon, who addressed http://www.eadt.co.uk/news/thurston-bury-st-edmunds-firm-s-pioneering-actiphage-tb-test-1-5714763
PBD Biotech have developed a new faster and more accurate way of testing cattle for TB. Picture: Ian Burt
A bovine TB test developed by a Suffolk firm looks set to be a game-changer in the battle against a disease which has plagued livestock herds all over the world and shows little sign of abating.
The notifiable disease has been rife in the west of the country - with TB-infected badgers blamed by some for the continuing problem - as well as in many other parts of the world.
But Dr Berwyn Clarke, chief executive of start-up firm PBD Biotech, based at Thurston, near Bury St Edmunds, believes the issue is not the badger - which has been the subject of a controversial government-organised cull over the last few years - but rather that the disease lies undiscovered in herds until it’s too late, because of the lack of a reliable test for it.
Or at least until now. Dr Clarke and a team at Nottingham university have worked on transforming a much older human diagnostic technology into a product which can be used on livestock and come up with a fast and accurate test result.
They have succeeded and they are now, with investors in place, ramping up the process of getting it to market.
“It’s a real game-changer - it’s unusual to find such a game-changer where there’s a massive gap in the global market,” says Dr Clarke. “There’s no competition to speak of, and it’s ready to go, so it’s quite unusual.”
Their Actiphage product is attracting interest from all over the world - and for good reason. In the UK alone, bovine TB has led to the slaughter of around 30,000 cattle and cost UK taxpayers more than £100m. Globally, it’s a multi-billion pound problem.
Bovine TB is one of a group of diseases (which also includes leprosy) caused by mycobacteria, which has devastated the agricultural industry worldwide. The Actiphage test, which detects live mycobacteria, can be used on blood or milk, and can also test for Johne’s disease. It has potential to be used for other livestock diseases as well.
It still has hurdles to overcome here with the Department for Environment, Food and Rural Affairs (DEFRA), but the test has been accepted for “exceptional private use” in England, according to an Animal and Plant Health Agency (APHA) protocol published in May of this year. This is significant, because it has meant that a Devonshire dairy farmer, who had previously despaired of ever getting on top of the disease and being able to function properly again, has worked in conjunction with his vet to eradicate the disease. In the course of that journey, they found the disease was still lurking in cattle previously considered free of it and have been able to work through the herd with the aim of wiping it out for good.
Dr Clarke hopes the product will be adopted as a pre-movement test, and believes it would be possible to wipe out TB completely in the UK, but progress in getting appropriate approvals here to ramp things up has been frustratingly slow. However, the firm is getting “serious interest” from UK milk testing laboratories.
Dr Clarke has a long history in the biotech field. He has a PhD in medical genetics, has worked on vaccines and antivirals, and has also worked for pharmaceutical giant Glaxo Wellcome. He moved into the diagnostics industry, setting up a company in Cambridge in 2005, Lab21, and is a board member of three other biotech firms. He believes the potential of Actiphage is “huge” and “really exciting”.
“We are fully commercial now. We are in the phase of application development. We have commercial kits which are available for a variety of different indications and now we are looking at specific applications for example the application of the technology for other animals - it’s massive,” he says. “Manufacturing we can do. We can manufacture enough samples for the entire world from the UK. It’s the customer adoption phase we are in now.”
Predict and prevent rather than test and treat says chief guest speaker Richard Sibley, a vet from Devon, who addressed the Pedigree Cattle Trust’s conference in Portadown recently
Fed up with testing cattle and seeing herds in his practice fighting a losing battle to escape the unending cycle of breakdowns and frequent tests, Mr Sibley worked with some proactive farmers to devise new means of eradicating TB from their herds.
A thorn in the side of DEFRA chiefs, Mr Sibley has introduced novel tests which have detected TB in stock which have passed the skin test on up to 30 occasions. He has also used a second test which detects TB in manure, with infectious cows being culled despite clear skin tests. He is also concerned about the risk of slurry as a source of infection.
r Sibley explained that in any herd there will be cows which are innately immune, some will be infected but the infection lies in a latent state and most of these cows never become infectious, while there will be some cows which are infectious and he says these must be identified and culled to have any hope of eliminating the disease on a farm.
He drew parallels with the human population, saying that one-third of the world’s human population is infected with TB but not all either show symptoms or are infectious to others. He said that one of the contributing factors to TB developing in humans is HIV which lowers the immune system.
Mr Sibley said that in one of the herds he had worked with, a single animal which was a BVD PI had its immune system compromised by the BVD which made it more susceptible to TB and meant it shed huge amounts of TB infection. Once it was culled from the herd the incidence began to fall dramatically.
Mr Sibley suggested four pillars to control TB:
q Biosecurity – try to keep it out in the first instance;
q Surveillance – find the carriers in the herd, especially those which are infectious;
q Resilience and immunity – how susceptible is your herd, vaccination may be an option; and
q Biocontainment – reduce the risk of spread, including early culling of infectious animals.
Predict and prevent should be the ethos rather than test and treat, said Mr Sibley.
One of the tests used by Mr Sibley is PCR which will look for shed fragments of the organism and this can be followed up with the phage test which is a very sensitive test of a blood sample to detect infected animals. He said it is important to differentiate between infected and infectious animals.
Dairy farming couple cleared of tampering with bTB tes
The farm had 150 cows 74 tested positive to infection and 21 inconclusive reactors. Thirty animals were slaughtered and a further 44 were kept on the farm in isolation for six months. This left only 50 cows being milked.
I can't get my head around that at all. It obviously gives further evidence that the skin rest is unreliable, and is causing stress to farmers. But, unless it's too early for my head, none of those figures add up.
The couple are now claiming compensation from DEFRA.

Government urged to remove hurdles to trialling Suffolk-made bovine TB test
Suffolk consultant biologist and farmer Tom Langton is calling on the government to adopt a bovine TB blood test because of the lack of reliability of the current test.
Consultant biologist Tom Langton, of Dews Farm, Bramfield, near Halesworth, said the Department of the Environment Food and Rural Affairs’ (DEFRA) approach to the cattle disease, affecting herds in the west of the country, was “a national scandal”.
He claimed government efforts to combat it weren’t working, and risked bringing it closer to East Anglia. He called on the department to take the necessary steps to adopt a blood (or milk) test developed by a Suffolk firm.
Officials currently rely on a skin test to detect the symptoms of bovine TB but this was unreliable, he argued.
Dr Clarke said he was making progress in introducing the test, which has been developed from an approved human test, in Canada, France and the USA - but not in the UK.
“If you want to have a licensed, registered test you have to have approval from the government, but the government won’t allow us to test our system,” he said. “It’s actually very difficult for any new technology to be adopted in the UK because of the reluctance of DEFRA to allow new technologies to be explored.”
When the veterinary surgeon arrived at a dairy farm in Devon recentlyy, he already knew at least 30 cows were infected with tuberculosis.
Their blood had tested positive using a new kind of TB test that is being pioneered by researchers at Nottingham University.
Yet when he felt the cows’ necks for the telltale lumps that reveal TB — which is the standard, government-backed way of detecting the disease — all 30 animals were clear, leaving their owner with a dilemma.
Read the rest of the stry at: https://www.thetimes.co.uk/article/test-finds-tb-rampant-in-dairy-herds-that-are-officially-disease-free-2kw2wchpw
Bovine Tuberculosis: Disease Control:Written question - 107782
Asked by Dr David Drew
Asked on: 16 October 2017
Department for Environment, Food and Rural Affairs
Bovine Tuberculosis: Disease Control
To ask the Secretary of State for Environment, Food and Rural Affairs, what plans he has to examine the effectiveness of the Phage and PCR tests for the testing of cattle for bovine TB.
Answered by: George Eustice
Answered on: 26 October 2017
Defra has provided financial and other support for research on a number of candidate diagnostic tests for M. bovis, the causative agent of tuberculosis in cattle, and continues to do so.
Neither the Phage nor PCR tests are currently validated to OIE (World Organisation for Animal Health) level for use in diagnosing TB in bovine species. If and when the manufacturers validate their tests we would consider their official use in TB control.
In exceptional circumstances, non-validated tests may be carried out on bovine species under strict criteria with the approval of the Secretary of State. This allows diagnostic companies to undertake the work required to validate the test.
The PCR test used in this instance is the same as that previously used to detect M. bovis in badger faeces and a comprehensive assessment of the PCR test (Defra study SE3289) indicated that this PCR test was not suitable for use in TB surveillance activities in wildlife. Until the PCR test is validated for use in cattle it is difficult to determine the percentages of truly TB-infected and TB-free animals that are correctly identified by this method.
Bovine tuberculosis testing
The Ecologist asks, 'Are the shortcoming of existing cattle TB tests soon to be exposed by a simple, clever blood test that has been waiting in the wings? The development may shine light on practical compromises in the extended, failing fight against TB in England - at huge tax-payers expense'.
Biologist TOM LANGTON looks at a growing dilemma in the world of bovine TB cattle testing.
Bovine tuberculosis testing
The Ecologist asks, 'Are the shortcoming of existing cattle TB tests soon to be exposed by a simple, clever blood test that has been waiting in the wings? The development may shine light on practical compromises in the extended, failing fight against TB in England - at huge tax-payers expense'.
Biologist TOM LANGTON looks at a growing dilemma in the world of bovine TB cattle testing.
As bovine TB is said to be spreading across the UK (and more badger cull areas have been agreed), it is no secret that the new government, like the previous is in turmoil over its response.
Chief Scientist Ian Boyd and now Chief Vet Nigel Gibbons are both leaving their roles.
Not specifically because spread of a disease that they have been unable to stop, but their time is up and they can slip away from the deteriorating situation. Interestingly both made it plain at the March 2017 London bTB conference that industry behaviour is holding progress back.
Read the full article. A history of the disease in the UK and alarming facts about existing controls. but will the new blood test bring the required results? What about vaccination - again this option seems to have disappeared from the agenda.
An East Anglian bio-tech firm has pioneered a new test for bovine tuberculosis (TB), which it claims could revolutionise the speed and accuracy of disease diagnosis.
PBD Biotech, based in Thurston, near Bury St Edmunds, has secured £200,000 of investment to commercialise its diagnostic kit, which detects the presence of disease-causing mycobacteria in blood and milk samples.
Founder and chief executive Dr Berwyn Clarke said the current testing method – which can take days to assess an immune response from the animal plus six weeks of laboratory work to confirm inconclusive results – is only 75pc accurate.
By contrast, he said his test could provide definitive, accurate results within six hours, which could save time money for farmers, and reduce animal stress.
He is in the process of securing the necessary approvals from animal health regulators, but said the first commercial kits could be ready as soon as October.
The new TB test could potentially bring major benefits to cattle farmers – but first it must win regulatory approval.
Shipdham dairy farmer Ken Proctor is a Norfolk representative on the Bovine TB Eradication Advisory Group for England (TBEAG).
After attending a meeting at the APHA (Animal and Plant Health Agency) laboratories in Weybridge in Surrey, he said: “It is one of several tests the APHA is watching with great interest. The problem at the moment is that it needs OIE (the World Organisation for Animal Health) approval.
Validation data presented today by researchers at the 4th Congress of the European Association of Veterinary Laboratory Diagnosticians (EAVLD) shows that Thermo Fisher Scientific’s VetMAX M. tuberculosis Complex PCR kit is a reliable tool to confirm the presence of mycobacteria belonging to the M. tuberculosis complex. Development of the new real-time PCR kit extends the company’s portfolio of tests for the detection of bovine tuberculosis (bTB). When used in combination with the company’s existing bTB portfolio, consisting of reagents for skin tests and IFNγ release assays (Bovigam), the newest solution provides veterinarians with an effective combination of tests for their bTB screening programs.
Dr. Jean Louis Moyen, Director of the Regional Analysis and Research Laboratory of Dordogne, France, who was among the scientists to present data at the conference, said: “We have tested positive and negative field lymph node samples from cattle, wild boar and badger with the VetMAX M. tuberculosis Complex Real-Time PCR kit in our laboratory as part of the validation study. The test showed excellent diagnostic sensitivity and specificity with 87 out of 88 infected lymph nodes correctly identified and no false positive results in the 284 samples tested. Implementation of the test in the lab was really easy.”
Enhanced Detection
The new PCR test detects all seven strains belonging to the Mycobacterium tuberculosis complex (i.e. M. tuberculosis, M. bovis, M. africanum, M. microti, M. canetti, M. caprae, and M. pinnipedii) and does not detect 42 other tested related pathogens. It includes a ready-to-use master mix and uses the Xeno internal positive control in a single well, duplex PCR approach.
“In the context of increasing TB prevalence, the field needs diagnostic tools that are easy to handle and provide sensitive, reliable and fast results to help ensure the efficacy of surveillance and control programs,” said Martin Guillet, global head and general manager of AgriBusiness at Thermo Fisher. “The results we present at the EAVLD show that this kit meets these expectations and is in line with our mission of enabling our customers to make the world healthier, cleaner and safer.”
The PCR-based kit is designed to reduce costs for the farmer and government-funded programs by delivering results typically in three hours instead of several weeks with bacterial culture, thus limiting the spread of infection while also reducing labor in the lab.
“The eradication of bTB is complex and the flexible application of testing schemes will help avoid unnecessary culling and lengthy farm closures, as well as help eliminate the occurrence of bovine TB worldwide,” Guillet said. “We feel this can shorten the overall length of a TB program in a country.”
The VetMAX M. tuberculosis Complex PCR kit is currently in development with registrations pending.
The European Commission has told anti-badger cull campaigners it backs investment in better tests for TB in cattle to help eradicate the disease.
Dominic Dyer, CEO of the Badger Trust and joint founder of a new Europe-wide badger protection group, said talks held with EU Commissioner and Acting Head of the Commission's Directorate for Heath and Food Safety Bernard Van-Goethem, should have brought the introduction of the gamma interferon blood test closer.
Mr Dyer, who reported back from the meeting in Brussels this week, said: “When pressed on the issue of gamma interferon testing for cattle, Bernard Van-Goethem confirmed that the European Food Safety Authority had found this test method when used in conjunction with the TB skin test, could result in the identification and removal of more TB infected cattle from herds.
“He confirmed that the Commission was happy to see EU funds being used for greater use of gamma interferon testing, although it is yet to be approved for TB free disease free status within the EU or the World Organisation for Animal Health.”
New bovine TB test being trialled
A DORSET vet is part of a team pioneering a new bovine TB test which could transform how cattle are assessed.
Alastair Hayton, of Synergy Farm Health, which is based at Evershot, said the new blood and or milk test – which has just been given the thumbs up by Defra to validate – will be significantly cheaper than the current interferon test, and is hoped will significantly aid the detection of bovine TB, especially in endemic TB herds, when used in conjunction with the current tests. The expectation is that it should help herds return to TB free status more quickly, as well as aiding in other areas such as pre or post purchase or movement testing.
The fact that there is the potential that milk could be tested to determine if an animal has the disease opens up a far easier method for farmers and vets to test cows.
Mr Hayton said: “We are pretty confident that the test can deliver what we need it to do, previous work suggests that it has the potential and we are hoping that the new form of the test will perform even better.”
The team includes experts from Scotland and Ireland. The test works by measuring antibodies to bovine TB, unlike the two tests which are currently used, the skin and interferon tests, which measure the cattle’s cellular response. The tuberculin skin test, used across Europe, works by injecting a small amount of tuberculin into the skin of an animal. If an animal is infected, the immune system will react and cause swelling a few days later.
Mr Hayton said: “The immune system can be described as having two arms. The first arm relates to cell mediated immune responses and the second arm relates to antibody related responses. It would make sense when detecting disease to use methods that will look for both areas rather than focusing purely on cell mediated responses, even if this side of the immune response to TB is considered to be the most important. This being particularly the case in bovine TB where we recognise that cell mediated responses can wane in the face of disease such that when chronically or severely infected cattle are tested with the skin test or interferon test they can fail to respond to the current tests.”
According to research by the University of Cambridge, the TB test currently used in Britain could miss as many as one in five TB infected cattle.
Mr Hayton said: “It is still in the late development stage but we have been told by Defra we can move towards validating it which is great news and hopefully we can move quickly to getting the data we need for it to be accepted at the EU and UK level.
“This is a big thing for the industry. You don’t get new bovine TB tests every day. We’ve had great support from the NFU in helping us to get where we are. We are looking at being on the cusp of going out and sampling cows and we will be looking for help from farmers in the next stage, as we will need permission to use the test on their animals and to have access to the follow up data.”
The new bovine TB testing contracts are being allocated to vets. Whilst TB testing remains such a lucrative part of veterinary business is it any surprise that vaccination is not being brought in for cattle?
Over a fifth of infected cattle found at slaughter? The skin test is not adequate. When will cattle vaccination be an option? Yet again badger culling has taken attention away from the most viable solution.
The Express carried an exclusive story yesterday (http://www.express.co.uk/news/uk/429440/EXCLUSIVE-Government-Chief-Vet-admits-he-can-t-define-what-s-a-humane-kill-of-badgers) proclaiming Government Chief Vet admits he can't define what's a 'humane' kill of badger. This beggars belief when the government has been stressing that the reason for the two ongoing badger culling trials are to test for how humane free shooting is.
The Government's Chief Veterinary Officer admitted there is “no definitive criteria” for measuring how humane the current pilot operations are.
Express Online has obtained a copy of a letter written from chief vet Nigel Gibbens in which he has admitted that ministers will have no hard and fast rules on what constitutes a humane kill when they come to decide whether the pilot badger cull has been a success.
The Department for Food and Rural Affairs (Defra) has previously insisted any decision to roll the pilots in Somerset and Gloucestershire out nationwide will significantly depend on whether killings have been humane.
A letter sent by Mr Gibbens to the Humane Society International UK on Thursday in which he tried to outline how the cull will be assessed said:
“Ministers will have access to advice from individuals with expertise in these areas [animal welfare and veterinary pathology].
“The independent panel includes individuals with such expertise, who will assess the results of the monitoring and report to Ministers.
“There are, however, no definitive criteria for determining humaneness in this context.”
Also disturbing from reading the excellent article, 'What I have learned about the badger cull', by a county councillor in Somerset, Mike Rigby, 'the marksmen are responsible for selecting which carcasses to forward for assessment. They’re hardly going to send in botched jobs for analysis are they?'
Green Party spokesman on animal issues Caroline Allen, who is a vet, demanded an immediate halt to the cull.
She said: “They don’t know how they are going to measure humaneness, so they are not going to be meeting a key objective of the cull.
“I think as the Government’s chief vet you have to take the welfare of the animals very seriously, and it seems he has neglected to do that.”
Genetic Predisposition to Pass the Standard SICCT Test for Bovine Tuberculosis in British Cattle (full report, published March 2013, can be accessed at www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0058245)
Bovine tuberculosis (bTB) imposes an important financial burden on the British cattle industry, yet despite intense efforts to control its spread, incidence is currently rising. Surveillance for bTB is based on a skin test that measures an immunological response to tuberculin. Cattle that fail the test are classified as “reactors” and slaughtered. Recent studies have identified genetic markers associated with the reaction of cattle to the tuberculin test. At marker INRA111 a relatively common ‘22’ genotype occurs significantly more frequently in non-reactor cattle. Here we test the possibility that the putative protective ‘22’ genotype does not confer resistance but instead causes cattle that carry it to react less strongly to the prescribed test, and hence avoid slaughter, potentially even though they are infected. We show that, after controlling for age and breed, ‘22’ cattle react less strongly to the immunological challenge and may therefore be less likely to be classified as a reactor. These results highlight the potential discrepancy between infection and test status and imply that the effectiveness of the test-and-slaughter policy may be being compromised by selection for cattle that are genetically predisposed to react less strongly to tuberculin.
Bovine TB Research Shows Promising Results
USDA scientists with the Agricultural Research Service are striving to improve tests and vaccination methods to overcome obstacles that prevent the eradication of bovine tuberculosis in cattle.
At the National Animal Disease Center in Ames, Iowa - scientists are developing better tests to help producers identify and remove TB-infected cattle from herds and keep healthy animals.
Veterinary Medical Officer Ray Waters says the tuberculin cattle skin test has helped eradication efforts - but has drawbacks - like a 72-hour waiting period for results.
Interferon-gamma release tests require live white blood cells that must be processed quickly.
Waters says traditional serum tests would be more convenient and less expensive.
Scientists have demonstrated that improved antigens - substances that cause the immune system to produce antibodies against foreign bacteria - are crucial in developing effective serum tests.
The findings were instrumental in the recent development of a new serum TB test.
Microbiologist Tyler Thacker - also collaborating on this effort at USDA - has developed another type of test based on polymerase chain reaction analysis of DNA.
This new test detects the causative agent of bovine TB in fresh tissues.
USDA says the test is quicker, accurate and helps distinguish between the causative agent of bovine TB and environmental mycobacteria that can cause false-positive results.
Info from: www.kmjnow.com/09/10/13/Bovine-TB-Research-Shows-Promising-Resul/landing.html?blockID=711987&feedID=806
Email from MG 5/6/13 draws out attention to the vervatum discussion that arose to the following extract from the EFRA report - '(Para 77) 'The mandatory skin test has a sensitivity of between 60-80% - i.e. it can miss up to 40% of infections. Johne’s disease, liver fluke, pregnancy and even the diligence of the tester can affect the result of the skin test'.
Q243 Chair: How accurate do you think the current tuberculosis skin test is?
Carl Padgett: We can go from the studies that Defra have the figures for. If we look at sensitivity, spotting those animals that are affected, there is a range of 60% to 80%. The more you undertake the tests-on lots more animals, on a full herd, for example-the sensitivity goes up because the more it is repeated, the more chance there is of finding the infected animal, so sensitivity increases. It is highly specific so you do not get many false positives with that particular diagnostic test.
Q244 Chair: The Commission said yesterday that, in their view, they thought it was 99% effective. You are saying 80% effective.
Carl Padgett: Specificity is 99.9% or greater. That means that, if you took 100 negative animals, 99 of them would come back as truly negative and one false positive might occur, to agree with a 99% figure.
Q245 Chair: Can the result be affected by another disease in the animal or the fact that the animal was pregnant? Would that have an implication for the skin test?
Carl Padgett: A number of infections have been looked at. There is certainly speculation about the role of bovine viral diarrhoea (BVD, which alters the immune status of the herd involved. So, are we getting the same reaction to the skin test when it is effectively an immune reaction that we are testing for? There is some work from the University of Liverpool recently that indicated the role of liver fluke in reducing the sensitivity of the test.
Q246 Chair: Do you think that non-reactive cattle are a source of transmission of TB?
Carl Padgett: With the characteristics of the test we have at the moment, it is highly likely that some herds have infected animals left at the end of the testing procedure, yes. Indeed, some work from Cambridge at the moment is looking at that. They published something saying along of the lines of one in four or five cleared herds may still have infected animals in them.
Q247 Chair: Do you think the skin test should be used in conjunction with other tests, such as the ancillary gamma interferon diagnostic test?
Carl Padgett: I think we have to try to deploy it as best we can within the armoury of other diagnostic tests, yes. One thing we need to remember about the skin test is that it has served worldwide, although in slightly different patterns and protocols for use, as a very good diagnostic and eradication tool. If we look at lowinstance areas of the country at the moment, it serves well there in the eradication of infection and the little foci of infection that appear. So it is a very good test that can actually eradicate the disease when we are dealing with the infection in focused elements of individual herds.
Q248 Barry Gardiner: It must be an awful thing to have to tell a farmer that one of their herd has reacted as positive. It can really devastate that farmer’s livelihood, can it not?
Neil Blake: Yes, it can. It is a difficult conversation to have every time it happens. Unfortunately, in the last 10 years or so, it is happening with increasing regularity. Yes, it is always a difficult conversation and I suspect Farm Crisis Network, for example, are a lot busier nowadays than they used to be.
Q249 Barry Gardiner: That means that the pressure placed on vets not to report, particularly where the results are borderline, is a real pressure. It is a human pressure.
Neil Blake: With every disease on a farm you are working with farmers to try to alleviate the problems associated with that disease. TB is a statutorily controlled programme. You apply the test diligently and we are required to notify where we discover disease. That is what we endeavour to do. So, irrespective of the difficult conversations we have to have, we are pretty well trained in terms of delivering that bad news.
Q250 Barry Gardiner: You will be aware of the practice on Anglesey last year where they were suspended from testing pending the completion of retraining of the staff, because the audit of their testing had shown that they were not being as rigorous as they ought to have been.
Carl Padgett: I am not aware of the specifics of the case as such, but I understand the generality. Yes, quality assurance of TB testing is a major issue and we have to have measures and procedures in place that ensure the test is being undertaken to the best of the veterinary surgeon’s ability to give the best results. We have a population of veterinary surgeons who are no different from any other human beings. Some people unfortunately, as with any system, may cut the odd corner or two, or feel that they have the most expeditious route of delivering the test. We therefore have to have an independent quality control mechanism, developed more robustly and delivered to ensure that veterinary surgeons are testing to the best of their ability. My own belief is that most of them are.
Q251 Barry Gardiner: This is a very sensitive area, and I am trying to ask these questions sensitively because I respect the job that these guys have to do and it is a tough one. Wales has adopted an auditing programme. Should we have an audit of tests in England to ensure there is not an underreporting of TB reactors by vets?
Carl Padgett: We should have an auditing system in place, and indeed we are involved with helping AHVLA develop one that makes sure testing is done properly, rather than for the avoidance of underreporting.
The Environment, Food and Rural Affairs Committee has published its report today on progress to develop a vaccine solution for bovine TB. In it it is scathing about the imperfect test. Bear in mind this test forms the backbone of existing policy ....
'We currently rely on a skin test that could miss one in four infected cows. Liver fluke, Johne’s disease and even pregnancy may impact on the result of the skin test. While the skin test has served us well, if other more sensitive tests exist, they should be employed alongside it. We accept that the gamma interferon blood test is expensive and not without limitations, but a test that catches infection earlier when animals are less likely to have transmitted the disease is a valuable tool and one that should be deployed as widely as possible. The Government should explore whether it is possible to improve the performance of the test and bring down its cost.'
'Farmers must be able to reassure themselves that the livestock they bring onto their farms are free of TB. We remain convinced that, alongside enhanced bio-security and movement control, improvements to the testing regime can deliver real benefits.'
''In 2012 alone more than 8 million tests were carried out on cattle in Great Britain and 37,754 cattle were slaughtered. According to Defra, there are approximately 10 million cattle in the UK: ‘a little over two million adult dairy cows in the UK, a little under two million adult beef cows, and about six million younger animals’. In 2012 it is estimated that 1% of the dairy herd was slaughtered because of bovine TB.''
(Para77) 'The mandatory skin test has a sensitivity of between 60-80% - i.e. it can miss up to 40% of infections. Johne’s disease, liver fluke, pregnancy and even the diligence of the tester can affect the result of the skin test'.

It is inevitable that increased bTB testing (necessitating handling cattle for two days each time), brings greater risks to human health than any risk of catching bTB.
We have been given details of the seven incident reports received by the Health and Safety Executive (HSE) involving injury as a result of bTB testing over the last few years. It is stressed that there may well be more as the search undertaken relied only on the use of the term 'TB'. In addition the HSE tends to deal only with employees - the self employed, we are told, are responsible for their own health and safety. Brief details are set out below.
There was no incident report for the Pembrokeshire farmer who died during TB testing earlier this year - because this case is still under investigation.
08/05/2009 a vet, whilst undertaking TB testing on a herd was pushing cow into crush from behind when another cow behind her kicked out causing lacerations.
19/05/2009 a vet - steer escaped during a TB test, charged and kicked right chest and shoulder.
19/06/2009 a vet - right arm, fracture to radius whilst reading TB test. He entered the pen where some cattle were being held and without warning one of the cattle kicked her right arm throwing her across the pen - she landed on her back.
11/04/2010 animal health officer, during TB testing a cow his arm was trapped between the animal and crush when he was trying stik a needle into the animal. - notes say possible broken are 'due to return to hospital to have an X Ray to determine whether or not it is broken'.
13/06/2011 farm worker kicked in abdomen during TB test.
'06/08/12 down as a major injury - he went to hospital. Farmer -'we were trying to put the cattle in the cattle crush ti do testing and one of the young heifers kicked out which made contact with the injured person on his back and he fell down. The heifer then tried to move away, on doing so it stood on the injured person's ankle.
31/01/2013 vet was undertaking TB test some cattle attempted to break out past the vet (herding them from the handling yard to shed where testing was taking place) who attempted to stop them and turn them around but he was knocked/fell to the ground and dislocated a shoulder.

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