Should young UK cattle be considered free of BSE or is it endemic?
A single case of a BSE infection was reported in June 2000 in a cow that had been born after the feed regulations were introduced in early August 1996 (born after the ban; a 1996-BAB). This article is aimed at showing how, and when it can be claimed, that such cattle are either vertically infected (in which case they may be of lesser significance) or represent a further mode of disease transmission of BSE in the UK, in which case UK beef may remain undesirable to foreign markets. These calculations require the age at which BSE infection takes place in cattle to be known: this is demonstrated to be within the first seven months of life and generally within the first month. The possibility that BSE cases infected before the feed ban in 1996 were the result of an environmental source is considered. It is shown that, should this be so, the case number seen in the UK would become greater than that predicted for vertical transmission between December 2000 and May 2001 assuming that the proportion of cases that are reported remains as previously.