§ Lord Lucasasked Her Majesty's Government:
What were the Veterinary Laboratories Agency's and the Wellcome Trust Centre for Epidemiology of Infectious Disease's forecasts for United Kingdom BSE cases in 2000 and 2001 (a) in 1997; (b) in 1998;
222WA(c) in 1999; and (d) at the latest date available; and to what factors any changes are ascribed. [HL2062]
§ Baroness HaymanThe Veterinary Laboratories Agency (VLA) provide estimates of future BSE cases in Great Britain for the current year and the following two years. These forecasts do not include Northern Ireland.
At any point in time there are insufficient data on current cases, such as results of all brain examinations, to extrapolate accurate estimates beyond that point. They did not therefore produce forecasts for 2000 or 2001 during 1997. Forecasts for 2000 and 2001 which have been produced by the VLA model are shown in the following table.
Predictions of the Number of Confirmed BSE Cases Expected in 2000 and 2001 (VLA) Year 2000 Year 2001 Date of Prediction Lower Central Upper Lower Central Upper September 1998 451 618 784 January 1999 548 729 911 April 1999 743 951 1159 June 1999 763 973 1183 260 393 526 October 1999 883 1,107 1,331 323 468 613 January 2000 889 1,114 1,339 325 470 615 April 2000 887 1,112 1,337 325 470 615 The Wellcome Trust Centre for Epidemiology of Infectious Disease (WTCEID) published forecasts of future BSE cases in 1997. If 10 per cent maternal transmission for the last six months of the incubation period is assumed, the number of BSE cases in 2000 and 2001 were estimated to be between 198–280 and 76–105 respectively. In 1999, the group presented revised estimates to the Spongiform Encephalopathy Advisory Committee (SEAC). In 2000, it was estimated that there will be 1,527–2,202 BSE cases and in 2001, between 733–1,283 cases. With the acquisition of additional data since 1996 and 1997, the confidence intervals surrounding the central estimates for cases in 2000 and 2001 have narrowed considerably.
Predictions of future BSE cases are based upon existing case data, knowledge of mechanisms of transmission and assumptions about the rate of decline of exposure. The models used by VLA and WTCEID outlined above are different. Each model will generate variations in the predictions depending on the set of criteria used and the process is continually refined to take account of the progress of the epidemic and improved understanding of the disease. The epidemic still continues to decline in line with the current, and therefore most accurate, predictions.