Summary of the 80th SEAC meeting
on 26th November 2003

The Spongiform Encephalopathy Advisory Committee (SEAC) held its 80th meeting in London on 26 November 2003, when it discussed the following matters:

Review of cattle bone in food production

The Food Standards Agency (FSA) asked SEAC to advise on the current knowledge of infectivity of bovine bone and bone marrow. In 1998, the detection of infectivity of sternal bone marrow from cattle (exposed orally to BSE) was reported using a mouse bioassay. The infectivity of bone marrow is being examined in the more sensitive cattle bioassay and no infectivity has been reported at 55 months post inoculation. SEAC agreed that the research from the cattle bioassay would indicate that the level of infectivity is at most very low; the single positive finding from the mouse bioassay may be an experimental artefact but could not be discounted. SEAC agreed that a more detailed risk assessment was required.

Report back from expert panel meeting on 17th September to discuss unconfirmed results in UK Scrapie Surveillance Survey

A survey published by Defra on the national surveillance of scrapie in Great Britain showed that the TSE status could not be determined for a small number of sheep (28 out of 29,201 abattoir sheep) due to inconclusive analytical results. The 28 sheep tested positive by the Bio-Rad Platelia assay but negative by immunohistochemistry (an OIE approved TSE test). An Expert Panel was called at the request of Defra and FSA to consider these results. Professor Bostock, Chair of the Expert Panel, informed SEAC of the panel’s discussions and recommendations. SEAC accepted the findings of the Expert Panel and endorsed their report. The Committee agreed that the research recommended in the report should be pursued.

Epidemiological update on Born After the Real Ban (BARB) cases of BSE

SEAC was updated on an epidemiological investigation of the 59 cases of BSE in animals in Great Britain born after 31 July 1996 (after the total ban on sale and supply of mammalian meat and bone meal (MMBM) or any feedstuff containing MMBM. These are known as born after the reinforced ban (BARB) cases.

SEAC concluded that although feed contamination was a plausible explanation for the findings, other hypotheses such as maternal or horizontal transmission or environmental factors could not be excluded as plausible explanation for at least some of the BARB cases.

SEAC recommended that it was important that genotyping, biochemical and strain typing studies were carried out in these animals. SEAC recommended that further investigations such as a case-control study were important.

vCJD Update

SEAC were updated on the latest figures from the National CJD surveillance unit. Up until November 3rd 2003, a total of 143 vCJD cases have been confirmed in the UK, including 6 cases still alive. All vCJD cases tested to date are of the same genotype at codon 129 of the PrP gene (methionine homozygous). Short-term analysis of the number of deaths from vCJD in the UK continues to show statistically significant evidence that the epidemic is no longer increasing exponentially.

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