SEAC : Public summary of the meeting on 21st/22nd September 1998

Public summary of the meeting on
21st/22nd September 1998

The Spongiform Encephalopathy Advisory Committee (SEAC) held a two-day meeting at the offices of the Ministry of Agriculture, Fisheries and Food, London on 21 and 22 September 1998.

The Committee conducted its regular review of research findings and epidemiological information on BSE and vCJD.

The number of cases of BSE continues to decline in line with predictions about the decay of the epidemic.

The Committee noted that the total number of vCJD cases in the UK remained at 27. Although there are no indications of an increase in the annual incidence of vCJD it is still too soon to make accurate predictions about the eventual size of the epidemic.

The Committee also reviewed the epidemiological data on feline spongiform encephalopathy. There is only a small number of cases (85 in Great Britain) but the epidemiological data is consistent with a food-borne source of infection. Gathering data is difficult, but the Committee concluded that further epidemiological studies should be initiated to learn as much as possible from this novel TSE of cats.

The Committee discussed the possible risks of transmission of vCJD through medical procedures consequent to the finding of abnormal prion protein in the appendix and tonsils of vCJD patients. The Committee agreed a summary of their discussions on reducing the risks of iatrogenic transmission which would be made available to inform further consideration of this issue by the joint ACDP/SEAC subgroup which had been set up to look at decontamination procedures and related matters. This working group would take SEAC’s views into account in their discussions and report back to the main Committees (ACDP and SEAC).

SEAC also considered the proposal to screen human lymphoid tissue, especially appendix and tonsils, for the presence of abnormal prion protein. While advocating that these studies should proceed they stressed that the results would need to be interpreted with great care. The presence of abnormal prion protein in lymphoid tissue would not necessarily indicate that the patient would later develop clinical neurological disease nor would it indicate the source. Negative results should also be interpreted with caution. Neither the sensitivity of the test, nor the stage of the disease at which abnormal prion protein would be found is known.

The Committee considered and supported a proposal for further studies of cattle which were offspring of BSE affected dams. The study would add to the understanding of the epidemiology of maternal transmission.

SEAC also reviewed proposals for disposal of excreta from large numbers of experimentally infected cattle in the MAFF research programme. They confirmed that after 28 days following oral inoculation the excreta could be composted for a year and then safely used to fertilise arable land and the crops subsequently grown could in principle be used for both human food and animal feed. Excreta from the first 28 days after challenge should be incinerated because if material from the oral inoculation were present in the faeces it would be during this period that the risk would be apparent.

The Committee again reviewed the practice of spreading condensate from rendering plants on farmland. They asked for further information as to exactly what went into the process which produced the condensate to be provided for their next meeting in order to come to a conclusion about the safety of this practice with regard to grazing animals. The Committee had previously concluded that any potential risk to human health from this practice was negligible.

Meeting with the Dormont Committee

On the 22 September SEAC were joined by the Dormont Committee, the French scientific committee on TSEs. The two Committees had previously met in Paris in February 1997. There was a broad exchange of information and views on CJD, BSE and scrapie in France and the UK. There was consensus between the scientists of both Committees on aspects of the epidemiology, genetics, pathogenesis and transmission of these TSEs and in the measures necessary to protect public health. They noted that there were complementary research programmes in place in France and the UK, including collaboration on EU research projects. The Committees agreed to hold a joint meeting again next year.

SEAC
October 1998