Enclosures

 

Question number 29 by Mr Peter Ainsworth to DEFRA

 

My analysis of these DEFRA figures.   

 


   Dr Ruth Watkins analysis of the answer to a parliamentary question tabled by Mrs Beckett 8th January 2002.

 

Summary table:

 

 Country

Total number of farms culled

Total number of IPs with a Positive laboratory result for FMD

Total number of IPs with a negative laboratory result for FMD

Total number of IPs never sampled:

Infection unconfirmed no lab diagnosis

% of IPs sampled **

+++

% of IPs incorrectly diagnosed

% DCs and CPs sampled

% of culled farms positive for FMD

Number of farms culled for each positive

Wales

806

60

42

13

102 of 115 = 88.7%

42 of 102 = 41.2%

20 of 664 = 3%

60 of 806 = 7.4%

746 for 60 = 12.4

Scotland

1572

110

58

19

168 of 187 = 89.8%

58 of 168 = 34.5%

37 of 1357 = 2.7%

110 of 1572 = 7%

1462 for 110 = 13.3

England

7083

1157

301

266

1458 of 1724 = 84.6%

301 of 1458 = 20.6%

339 of 5157 = 6.6%

1157 of 7083 = 16.3%

5926 for 1157 = 5.1

 

 

 

 

 

 

 

 

 

 

Totals

9461

1328

 

 

 

 

 

 

 

 


Notes on my analysis of the figures:

 

** DEFRA have moved the DCs and CPs and SOS that were laboratory positive into the IP column.  I am told by Roy Hathaway these were labelled IP at the time when the positive results came back. The current total of IPs is given as 2026.  In my opinion the total number of FMD infected farms is 1328, those that were proven to be infected on laboratory testing.  298 farms are of indeterminate status, and could be broken down into those which were diagnosed with typical FMD infection in a number of cattle and those in which the likelihood of FMD is clinically doubtful, such as one bovinel only involved or the diagnosis made in sheep and not cattle etc.

 

However DEFRA have not removed the IP designation from those that tested negative in the laboratory. The case of the Dents is enclosed as an example of this policy.  This meant that farms under section D notices remained so and are now consequently saddled with huge debts with no prospect of compensation.

 

            When samples are taken from animals that display symptoms of FMD, (young lesions will be virus positive and in the case of old lesions the animal will be seropositive), then the laboratory can normally be expected to obtain positive results (either virus or specific antibody).  FMD is not difficult to diagnose in the laboratory and I am sure the standards at Pirbright were high. 

            Difficulty arises when sampling animals early in the incubation period as when DCs or CPs are sampled at the time of clinical diagnosis in the index IP.  If the animals on the DC or CP are well then it is possible they have not been infected at all and are not incubating infection or that they have been exposed and infected and are incubating FMD.  In the latter case Fred Brown advised that sampling on day 0 and day 3  by a sensitive virus detection test such as PCR would resolve most cases.

            With regard to keeping laboratory negative farms as clinical confirmed IPs, this reflects a lack of understanding of the role of the laboratory.  Roy Hathaway said it was his and DEFRA’s judgement call but I told him he is not qualified to make it.  The new farmgate tests will be validated by comparison with the standard laboratory tests on duplicate samples (when a farm is reported as having animals ill with possible FMD).  These standard laboratory tests were done in this epidemic, and if in future a negative farmgate test is accepted as such (which is the whole point of doing farmgate testing, to avoid culling uninfected farms) then it makes no sense to insist on retaining laboratory negative farms as confirmed cases as IPs.  It also invalidates any epidemiology on the epidemic as the figures are wrong.  

 

+++  After the 30th of September antibody positive sheep flocks were culled on the basis that these were past infections and therefore one could reason these were not IPs (!)  (this would not interfere with the 3 month period of waiting for OIE FMD-free status that Jim Scudamore had applied for). There have been 40 to50 of such flocks.  The cattle were neither tested nor culled on the same farms as the sheep that gave positive serology tests according to Jim Scudamore (personal communication).  I strongly suspect that these are not included as DEFRA have been determined not to call these IPs at all:  no new IPs were published after 30th September.  .

 

Because the figures are not clarified for the CPs and the DCs one can attempt no more than an overall view.  It is likely that the CPs tested were fairly early in the epidemic, probably in one place, perhaps Cumbria, and may have been triggered by undisclosed events and motivations such as to justify killing contiguous premises. 

 

As you can see from the notes 120 CPs tested positive, and 218 tested negative, altogether 338 must have been sampled (not just 218) - it should be 3425 CPs altogether.

 

The laboratory negative farms in the IP column must be clinical misdiagnoses, roughly 30 %.  (It has been previously published that sheep suspected of FMD have a 50% likelihood of having something else – no samples were taken from sheep for virus infections other than FMD, these would have to be sent to a different laboratory.  This also argues for a multiple PCR for sheep that includes orf and FMD for mouth lesions).  The variation among counties is likely to reflect variation in veterinary clinical acumen – this was low in Wigtown for example.  In Cumbria where there was comparatively the highest ‘weight ‘ of infection clinical diagnosis appeared to be more accurate- there may have been sufficient cases for vets to improve clinical acumen and they were less likely to be wrong (the same sheep flocks could have had orf and FMD).

 

Mrs Beckett’s tables do not provide information on which domestic animal species the diagnosis was made, nor the details of the laboratory diagnosis.  I know of one farm which was labelled a laboratory positive diagnosis when the virus was only found in sheep after arrival at the abattoir and not on the farm itself- this was contamination at the abattoir because 2 other farms which delivered sheep at the same period went down with FMD 2 days and one week later.  This also shows that we were eating acutely infected animals particularly lamb. 

 

It is also notable that in several regions relatively large numbers of farms were culled out for each laboratory confirmed positive.  There was clearly excessive culling in Wigtown and Gwynedd.

 

We should remember that for every IP, and the contiguous farms culled with it there were many times more farms given a section D stand still notice.  These farms continue to suffer the consequences now whilst the culled and compensated farmers have had the chance of a clean slate.

 

 

 


Details of selected counties (from the answer to the parliamentary question asked by Peter Ainsworth and tabled by Mrs Beckett

 

 

County

Total number of farms culled

Total number of IPs with a Positive laboratory result for FMD

Total number of IPs with a negative laboratory result for FMD

Total number of IPs never sampled:

Infection unconfirmed no lab diagnosis

% of IPs sampled

 

**

+++

% of IPs incorrectly diagnosed

% DCs and CPs sampled

% of culled farms positive for FMD

Number of farms culled for each positive

Powys

392

44

23

7

67 of 74 = 90.5%

23 of 67 = 34.3 %

11 of 304 = 3.6%

44 of 392 = 11.2%

348 for 44 = 7.9

Gwynedd

230

5

5

2

10 of 12 = 83.3%

50%

5 of 211 = 2.4%

5 of 230 = 2.2%

225 for 5 = 45

Gwent

149

9

13

3

22 of 25 = 88%

13 of 22 = 59 %

3 of 119 = 2.5%

9 of 149 = 6%

140 for 9 = 15.6

 

 

 

 

 

 

 

 

 

 

Shropshire

131

5

3

4

8 of 12 = 66.7%

3 of 8 = 37.8 %

4 of 113 = 3.5%

5 of 131 = 3.8%

126 for 5 = 25.2

Cheshire

53

7

9

1

16 of 17 = 94%

7 of 16 = 44%

5 of 33 = 15.2%

7 of 53 = 13.2%

46 for 7 = 6.6

Lancashire

271

44

7

2

51 of 53 = 96.2%

7 of 51 = 13.7 %

22 of 215 = 10.2%

44 of 271 = 16.2%

227 for 44 = 5.2

Cumbria

2844

675

86

131

761 of 892 = 85.3%

86 of 761 = 11.3 %

108 of 1911 = 5.7%

675 of 2844 = 23.7%

2169 for 675 = 3.2

Northumberland

413

58

17

13

75 of 88 = 85.2%

17 of 75 = 22.7 %

22 of 313 =    7%

58 of 413 = 14%

355 for 58 = 6.1

North Yorkshire

764

122

10

1

132 of 133 = 99.2%

10 of 133 = 7.5 %

63 of 611 = 10.3%

122 of 764 = 16%

742 for 122 = 6.1

West Yorkshire

34

8

0

0

100%

0%

4 of 25 = 0.16%

8 of 34 = 24%

26 for 8 = 3.25

Wigtown

218

2

11

2

13 of 15 = 86.7%

11 of 13 = 84.6 %

0 of 200

2 of 218 = 1 %

216 for 2 = 108

 

 

 

 

 

 

 

 

 

 

Devonshire

1012

98

45

29

143 of 172 = 83.1%

45 of 143 = 31.5 %

28 of 801 = 3.5%

98 of 1012 = 9.7%

914 for 98 = 9.3