i) Definitive evidence on the accuracy of the Pirbright tests.
(Dr Kitching affirms that the tests are sensitive, reliable and are capable of detecting FMD in its various stages. See below.)
In the early days of the epidemic, MAFF policy was to stress how thorough the testing was to detect the presence of FMD virus and antibodies. Ms Quin in a Parliamentary Answer to Mr Jenkin on March 30th said of the testing routine, "Where it is necessary to take samples for testing, these are collected, packaged and despatched to the Institute for Animal Health at Pirbright in surrey. The IAH carries out an ELISA test which takes about 5-6 hours to complete. Positive results are then faxed to MAFF's Emergency Control Centre in London for immediate action. The ELISA test can give false negative results and so all negatives are checked by attempting to isolate the foot and mouth virus in a cell culture. This process can take 4-5 days to complete."
However, that description was later changed, and Ministers started describing these tests as not very accurate. This was frequently the information given over the phone by Animal health offices, when asked why healthy animals had been killed. DEFRA's Ray Anderson, referring the negative blood tests that came back for the slaughtered sheep at Bardon, Cumbria famously stated that a negative test did not mean that the animals weren't infected. "While the test is robust in establishing the presence of virus it is not sufficiently robust to say there is definitely no virus there." (Westmorland Gazette, October 12th)
Similarly,Mr Morley, on July 17th in a written Answer to David Maclean about slaughter and negative tests stated, "A negative test result does not necessarily mean that the premises was free from disease. For instance, positive results may not be produced from tests on blood or tissue taken when the disease is in later stages or from newly infected animals where antibodies have not yet developed."
This is incorrect information, and has been completely refuted by Kitching and Donaldson in their letter "FMD Diagnosis" to the Veterinary Record, May 19th....... The VR letter details the tests carried out by Pirbright, highlights the great accuracy, and reminds one of the world class status of Pirbright as a FMD testing centre. For the Ministers to be casting aspersions on Pirbright tests is quite frankly laughable.
My own personal research has confirmed the above. On May 21st I spoke on the telephone with Tony Garland, Pirbright about the testing, with particular reference to the massive slaughter that I feared was going to take place in the Settle district. He reassured me (wrongly as it happens) that he did not think slaughter on a large scale would take place in this area because Pirbright had the necessary accurate and quick tests available. What he envisaged was the slaughter of the Infected Premises with monitoring and testing of surrounding areas.
Finally the ultimate confirmation that the Ministers' statements were inaccurate came in e-mails (dated October and November) from Dr Kitching, in response to a communication asking for his comments on the above statements by Anderson and Morley. He said,
"Blood samples received at Pirbright are tested for both virus and antibodies; if both are negative then it would not be possible for that animal to have or have had FMD assuming they sent samples from the animals they suspected of having the disease ... the blood tests approach 100% accuracy."
"Epithelial samples were tested by ELISA, PCR and tissue culture the tests are very sensitive and specific, approximating 100%".
In a recent e-mail to me he stated, "If we assume that samples were collected on IPs from animals with suspect clinical signs, the these are very sensitive and specific, approximating 100%. The samples were tested by ELISA, PCR and tissue culture.
If blood was submitted, this was tested for virus and antibody. Virus appears before clinical signs, so if an animal had suspect FMD, it would be virus or antibody positive, some times both, never neither. Again the tests approach 100%."
sent by Anne Lambourn