Volume 16: Reference Material
3. Statistics
Confirmed cases: contemporaneous and revised

3.16 The real extent of BSE, in its earlier stages at least, was always one step ahead of the latest available reported or confirmed figures (see also paragraphs 3.5-3.6). Figures 3.30a and 3.30b below give the same example, in figures and graphically, of how the confirmation figures were revised for the period between November 1987 and March 1990, with later confirmations assigned to the date of clinical onset. The first set of figures in Figure 3.30a is what was available to Ministers and others at the time to indicate the extent of the epidemic; the second set shows the true extent of it as revealed by later confirmation of cases which had earlier onsets.

Figure 3.30a: Cumulative totals of confirmed cases of BSE in cattle in Great Britain, November 1987 to March 1990: those reported at the given date, compared with confirmations as at 20 March 1996 by date of clinical onset

Figure 3.30b: Cumulative totals of confirmed cases of BSE in cattle in Great Britain, November 1987 to March 1990: those reported at the time, compared with confirmations as at 20 March 1996 by date of clinical onset