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15 Jan 2007 : Column WA115

Written Answers

Monday 15 January 2007

Agriculture: Scrapie

Lord Greaves asked Her Majesty's Government:

The Minister of State, Department for Environment, Food and Rural Affairs (Lord Rooker): The National Scrapie Plan (NSP) was launched in 2001 against a background of concern about the risks from transmissible spongiform encephalopathies (TSEs) in sheep (that is, scrapie) and the theoretical risk of bovine spongiform encephalopathy (BSE). Its complementary aims have been to protect both public health and animal health and welfare by increasing the TSE resistance of the national flock, principally through its voluntary ram genotyping scheme (RGS).

The Veterinary Laboratories Agency has tested samples where suitable material has been available from all sheep diagnosed as positive for scrapie, from 1998 to the present time, for the possible presence of BSE. Samples from nearly 3,000 animals have been tested and all have been negative for BSE. Recently, in the light of this testing, and the latest scientific knowledge and research, the Spongiform Encephalopathy Advisory Committee's sheep sub-group was asked to consider the latest science underpinning the RGS. It concluded that the prevalence of BSE in the UK sheep population is most likely to be zero, or very low if present at all, and that consequently the current RGS would have little impact on public health. They concluded that the RGS was still scientifically valid with respect to

15 Jan 2007 : Column WA116

animal health to protect against classical scrapie. The subgroup's statement is available at http://www.seac.gov .uk/statements/sheepsubgrp-statement131006.pdf.

The voluntary breeding programme elements of the NSP which include the RGS (but not the statutory, EU-required elements including compulsory controls on scrapie-affected farms) are currently under review.

Lord Greaves asked Her Majesty's Government:

Lord Rooker: No reliable estimate is available of the distribution of the 15 known scrapie genotypes of sheep in the national ram flock prior to the commencement of the first National Scrapie Plan (NSP) genotype testing in 2001. Relatively few breeds had been commercially testing their rams prior to 2001. Modelling done prior to the NSP(1) estimated that approximately 28 per cent of rams were of the most resistant genotype that carries two copies of the ARR allele (the allele that is most resistant to classical scrapie) and that thus had the “ARR/ARR” or NSP Type 1 genotype.

There are 420,000 rams and ram lambs in the national flock. Since 2001, the NSP has tested over 2.6 million sheep (in all schemes) in Great Britain. Table 1 below shows the genotypes of all those sheep. Table 2 illustrates the change in the allele percentage of ram lambs born in flocks participating in the NSP from 2002 to 2005 (the ARR allele is the most resistant to classical scrapie and the VRQ is the most susceptible in the majority of breeds). The ram lamb data for 2002 are a good starting point as the majority of these animals will have been the progeny of previously untested rams as NSP testing only commenced on a small scale in October 2001.

(1) Arnold et al. Published in Preventative Veterinary Medicine 56, 227-229 (2002). (2) Gene component derived from one parent and contributing hereditary information from that parent.

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Table 1 NSP data as at 29/12/20062001-06 All sheep tested in all NSP schemes
NSP TypeGenotype & Degree of resistance/susceptibility to classical scrapieNumberPer cent

I

ARR/ARR

Sheep that are genetically most resistant to scrapie.

849,304

32.3%

II

ARR/AHQ

Sheep that are genetically resistant to scrapie, but will need careful selection when used for further breeding.

251,464

9.6%

ARR/ARH

143,612

5.5%

ARR/ARQ

714,617

27.1%

III

AHQ/AHQ

Sheep that genetically have little resistance to scrapie and will need careful selection when used for further breeding.

40,552

1.5%

AHQ/ARH

10,061

0.4%

AHQ/ARQ

139,571

5.3%

ARH/ARH

35,488

1.3%

ARH/ARQ

35,961

1.4%

ARQ/ARQ

237,291

9.0%

IV

ARR/VRQ

Sheep that are genetically susceptible to scrapie and should not be used for breeding unless in the context of a controlled breeding programme approved by the NSP Administration Centre.

90,708

3.4%

V

AHQ/VRQ

Sheep that are highly susceptible to scrapie and should not be used for breeding.

20,236

0.8%

ARH/VRQ

6,039

0.2%

ARQ/VRQ

48,755

1.9%

VRQ/VRQ

4,489

0.2%

Unknown

-

4,940

0.2%

Total tested

2,633,088

100.0%

Table 2 Changes in allele per cent frequencies of ram lambs 2002-05
ARRAHQARHARQVRQ

2002

50.4

7.4

9.9

29.2

3.0

2003

55.6

7.5

7.7

26.9

2.3

2004

62.0

6.5

6.9

22.9

1.7

2005

65.4

5.9

6.3

20.9

1.5

Lord Greaves asked Her Majesty's Government:

Lord Rooker: Some 155 cases of atypical scrapie in sheep have been detected in Great Britain. The table below breaks this down by year and genotype. Nearly all (149) have been detected through the “active” surveillance programme launched in 2002. Under this programme, almost 206,000 brain samples from sheep sent for slaughter and from fallen stock have been tested thus far for the presence of a transmissible spongiform encephalopathy. The remaining six cases have been detected through passive surveillance (animals reported as exhibiting clinical signs).

Data as at 3 January 2007
NSP TypeGenotype20022003200420052006Total

I

ARR/ARR

3

7

4

1

1

16

II

ARR/AHQ

4

11

4

12

11

42

ARR/ARH

-

1

-

-

-

1

ARR/ARQ

2

7

1

3

5

18

III

AHQ/AHQ

4

6

1

2

7

20

AHQ/ARH

-

-

1

-

2

3

AHQ/ARQ

3

14

2

3

12

34

ARH/ARH

-

-

-

-

-

-

ARH/ARQ

-

-

-

1

-

1

ARQ/ARQ

2

5

3

3

6

19

IV

ARR/VRQ

-

-

-

-

-

-

V

AHQ/VRQ

-

-

-

-

-

-

ARH/VRQ

-

-

-

-

-

-

ARQ/VRQ

-

1

-

-

-

1

VRQ/VRQ

-

-

-

-

-

-

Total

18

52

16

25

44

155


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