Select Committee on Environment, Food and Rural Affairs Minutes of Evidence

Supplementary memorandum submitted by Professor David King, Chief Scientific Adviser, Office of Science and Technology

  Thank you for your letter of 7 November, in which you asked me to provide further material relating to the answers I gave at the evidence session earlier that day. I apologise for the delay in replying. This was caused by having to obtain further information from various sources.

  First; on testing for BSE in sheep. Between November 2000 and the end of September 2001, 465 sheep scrapie suspects have been tested at the Veterinary Laboratories Agency using a molecular testing method based on a modified version of a Western blot test used to detect BSE in cattle. 284 were found to be positive for scrapie; none have given results that suggest BSE. However, this test remains unvalidated for distinguishing between BSE and scrapie.

  Scrapie-infected sheep brains, collected since 1996, are also being strain-typed at the Institute for Animal Health, using mouse bio-assay. In about 180 cases this work has reached the first point at which, if BSE were clearly present, it should have become apparent. It has not done so, but the work is still ongoing and these experiments cannot yet be interpreted as being definitively negative for BSE.

  The second query was about the current incidence of BSE in cattle. The BSE epidemic peaked in the UK during the winter of 1992-93, when over 1,000 suspected cases were being reported each week. In the current year, clinical BSE cases are likely to be around 750 and the epidemic appears to be declining broadly in line with epidemiological predictions. Active surveillance checks have been, or are being, carried out by MAFF/DEFRA to find levels of sub-clinical disease in cattle. These are:

    —  Surveys of animals aged 5 years and over, presented for slaughter under the Over Thirty Months Slaughter Scheme from January to March 1999 and from May to December 2000.

    —  Since 1 January 2001, any animals aged over 30 months and slaughtered for human consumption must be tested for BSE before the carcass is released. In the UK, this relates to a small number of animals from herds belonging to the Beef Assurance Scheme.

    —  A voluntary survey of fallen stock aged 30 months and notified to the department from January to July 2001, superseded by a compulsory survey that began on 1 July 2001.

    —  A survey of animals aged 30 months or over and subject to emergency slaughter (casualty animals) also began on 1 July 2001.

    —  Cattle born between 1 August 1996 and 31 July (the year after the effective feed ban) as they enter the Over Thirty Month Scheme. This testing began in September 2001.

    —  Testing the offspring of BSE cases aged over 30 months from 10 September 2001.

    —  From January 2002, 24-30 months fallen stock and casualty cattle will be tested.

  This testing has found pre-clinical cases of BSE, but not at a level so far to indicate that the disease exists widely in an undetected state.

  The Committee's third request was for my comments on a written answer given by Elliot Morley (HC Deb, 6 November 2001, 146W) relating to the number of premises culled out as Dangerous Contacts and Slaughter on Suspicion cases which were found subsequently to have Foot and Mouth Disease. I understand that DEFRA will shortly be issuing a corrected answer and that the relevant figures are: 284 premises currently classified as Slaughter on Suspicion and 396 premises currently classified as Dangerous Contact had laboratory tests conducted for the presence of Foot and Mouth Disease. Of these, one returned an initial positive result.

  The fact that all but one of the premises have tested negative does not mean that the policy of culling out Dangerous Contacts and Slaughter on Suspicion cases is too stringent. FMD is an extremely infectious disease and, in order to bring the epidemic under control, it was necessary to get ahead of the infection by removing animals that were potentially already incubating the virus and, if not slaughtered, would themselves pass the infection on. Currently available diagnostic tests are not fast or sensitive enough to spot incubating infection quickly enough to prevent it becoming a risk to surrounding farms.

13 December 2001

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