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21 July 2008

Bovine Tuberculosis: Disease Control

Mr. Paice: To ask the Secretary of State for Environment, Food and Rural Affairs what research his Department has commissioned on the role of maize and trace element deficiency in the spread of M.bovis. [218918]

Jonathan Shaw [ holding answer 15 July 2008] : While the role of maize in the spread of Mycobacterium bovis (M. bovis) has not been specifically investigated by any DEFRA funded research projects, the case-control studies carried out as part of the Randomised Badger Culling Trial (RBCT) did investigate associations between a number of feed types and risk of a herd TB breakdown. Studies TB99 and CCS2005, found an association between feeding silage and the use of grass feeding types for grazing/forage and an increase in risk of TB breakdown, respectively. The findings of these studies are in the final report of the Independent Scientific Group report on cattle TB In addition TB99 also identified not using feeding supplements as a risk factor for confirmed cases of TB.

The association between M. bovis infection and trace elements such as selenium, copper and vitamin B12 status of cattle was investigated as part of the DEFRA  funded project “Pathogenesis and Diagnosis of Tuberculosis in Cattle - Complementary Field Studies” (project SE3013), carried out at the Veterinary Laboratories Agency (VLA). While little evidence was found for a difference by TB status in copper or B12, associations were found between low levels of selenium and a higher risk of an animal being infected with M.bovis. However, given the design of the study and the evidence that the action of some micro-nutrients can be substantially influenced by the levels of others it was not possible to conclude that the observed associations were causal. The full report can be downloaded from DEFRA’s website.

I remain open minded about the possibility of a nutritional link but because of the number of variables involved and the likelihood a causal link could never be proven I am not inclined to fund further research into this subject.

Mr. Paice: To ask the Secretary of State for Environment, Food and Rural Affairs what assessment he has made of the effectiveness of the cattle testing regime in preventing cattle-to-cattle transmission of bovine tuberculosis; and what representations he has received on the frequency of the tests under the regime. [218919]

Jonathan Shaw [holding answer 15 July 2008 ]: The underlying principle of our bovine TB test and slaughter programme is to identify infected cattle as early as possible and minimise the risk of the transmission of the disease within and between cattle herds. Many countries where infection is maintained solely through spread between cattle have eradicated bovine TB through the systematic testing and reactor slaughter programme that we use today.

DEFRA has funded, and is currently funding, a number of research projects modelling the potential impacts of various cattle movement control scenarios on the spread of TB - final reports are published on the DEFRA website. We recognise the importance of monitoring the effectiveness of the TB control programme - and we will enhance controls in the light of emerging evidence. New policies introduced in recent years include: zero tolerance for overdue TB tests (i.e. herd movement restrictions applied immediately a test becomes overdue); mandatory pre-movement testing of cattle in high risk areas; and increased use of the gamma interferon blood test. These measures increase our ability to identify infected cattle, thereby reducing the risk of disease spread. We have also been working with stakeholders to raise awareness of simple biosecurity measures to further reduce transmission risks between animals.

Increasing the frequency of bovine TB testing in some areas was one of the additional measures recommended by the Independent Science Group (ISG). Initial cost benefit analysis of increasing the frequency of cattle testing suggests that they would come at a high cost with limited benefits - and so would be difficult to justify in terms of Government expenditure. Decisions about the value of such measures, and how they might be funded, are as much, if not more, a question for industry as for Government and will need to be discussed by the Bovine TB Partnership Group.

Our current approach to determining the minimum levels of routine testing for cattle herds is risk-based and consistent with the requirements of EU Council Directive 64/432/EEC. Parish Testing Intervals reflect the local level of bovine TB prevalence, and are reviewed each year to take account of any change in the disease situation. An increase in the levels of disease in an area triggers more frequent testing. Divisional Veterinary Managers (Animal Health) are already empowered to increase testing if local or individual herd circumstances indicate that such action is required.

Mr. Paice: To ask the Secretary of State for Environment, Food and Rural Affairs what estimates he has made of the number of cattle likely to be slaughtered under the bovine tuberculosis regime in the next three years. [218920]

Jonathan Shaw [holding answer 15 July 2008]: My Department has not attempted to estimate the numbers of cattle likely to be slaughtered under the bovine tuberculosis control regime in the next three years.

It is very difficult to make such forecasts due to the chronic, multifactorial and insidious nature of bovine TB. The number of cattle slaughtered as tuberculosis (TB) test reactors and direct contacts largely depends on (i) the underlying prevalence of the infection in the cattle (and badger) population and (ii) the intensity and accuracy of the TB screening programme for cattle herds. The former is subject to cyclical changes in the endemic TB areas that are difficult to predict, whereas the latter is subject to annual changes as TB herd testing frequencies are reviewed every year in response to the incidence of herd breakdowns in the previous years. Furthermore, the enhancements to the TB testing regime introduced over the last two years (such as pre-movement testing and gamma-interferon blood testing) are expected to result in higher numbers of reactors being identified each year, at least in the short to medium term.

Mr. Paice: To ask the Secretary of State for Environment, Food and Rural Affairs pursuant to the Statement of 7 July 2008, Official Report, columns 1157-8, on bovine TB, if he will publish the evidence which underlay his evaluation of the PCR test reported to the House on 7 July 2008. [219028]

Jonathan Shaw [holding answer 15 July 2008]: A number of diagnostic tests for the detection of Mycobacterium bovis ( M . bovis) infection in badgers have been developed through DEFRA funded research projects at the Veterinary Laboratories Agency (VLA). The final reports of completed research projects have been published on the DEFRA website.

Bovine TB is currently confirmed by culture of M. bovis in the laboratory. However, M. bovis grows very slowly so culture results can take six weeks to several months to come through. DEFRA funded VLA project SE3008 (April 1999-December 2004), ‘Detection and enumeration of M. bovis from clinical and environmental samples’, aimed to develop PCR-based methods that may allow rapid screening of samples from infected cattle and monitoring of the environment and badger populations for the presence of M. bovis. This research showed that while the PCR test specific for M. bovis was found to be only 50 per cent. as sensitive as the gold standard of culture, the sensitivity of the M. tuberculosis complex PCR test (i.e. a less specific PCR able to detect mycobacteria that are members of the M. tb complex) was increased from 70 per cent., to 90 per cent., by the end of the project. While such low sensitivities for M. bovis detection rules out the use of this PCR test for use on environmental samples and excretions collected from badgers, with further development and evaluation this test could be used in the laboratory to achieve faster confirmation and subsequent tracing of bTB infection in slaughterhouse cases.

Work funded by DEFRA to validate the PCR test developed by Warwick University to detect M. bovis in the environment is ongoing (Project SE3231: ‘Validation and epidemiological application of molecular methods for monitoring M. bovis survival and dissemination into the environment’). This is a joint project between the VLA, Warwick University and University College, London and includes validation of the test using field samples. A full project description is available on the DEFRA website. A final report on the work will be published following its completion in April 2010.

If it is shown to be usable as a robust practical field test, consideration of its potential use in any bTB control policy will need to take account of the results of the Randomised Badger Culling Trial, which showed that localised culling was associated with an increase in cattle herd TB breakdowns due to the perturbation effect on badgers and increased transmission of bTB.

Mr. Paice: To ask the Secretary of State for Environment, Food and Rural Affairs if he will give a breakdown of his Department's expenditure on bovine tuberculosis expenditure in 2007-08 by main budget heading; what estimate he has made of such expenditure for the rest of the current comprehensive spending review period; and what assumptions underlay that estimate. [219029]

Jonathan Shaw [holding answer 15 July 2008]: GB expenditure on bovine tuberculosis (bTB) in 2007-08 was £79.8 million. However, we are unable to provide an accurate forecast of expenditure on bTB in the period of the 2008-11 comprehensive spending review as budgets have not yet been finalised.

The following table shows the breakdown expenditure on bovine TB in 2007-08;

Activity 2007-08

Cattle Testing






Surveillance activity by the VLA


Other Research(1)






(1) Figure does not include research into culling methods or the badger population survey.
1. Cattle testing - the cost of carrying out the testing of cattle for TB by arranging, assessing and monitoring tests, conducting investigations of incident herds and diagnostic testing by local veterinary inspectors on behalf of DEFRA. Note: These costs include Scotland and Wales (funded by DEFRA).
2. Compensation - includes payments for 'reactors' and 'contact animals' which are compulsorily slaughtered. This includes 'salvage' money received by the Government for those carcasses which are permitted to go into the food chain or are eligible for over 30 month scheme payments. Note: These costs include Scotland and Wales and are funded by their respective Governments.
3. Surveillance activity by the VLA - includes all DEFRA-funded work carried out by the Veterinary Laboratories Agency relating to TB in cattle and badgers including the supply of tuberculin.
5. HQ/overheads - includes staff costs for veterinary advice and administration of TB policy in England, Scotland and Wales.