Volume 12, Number 12—December 2006
Perspective
On the Question of Sporadic or Atypical Bovine Spongiform Encephalopathy and Creutzfeldt-Jakob Disease
Paul Brown*
, Lisa M. McShane†, Gianluigi Zanusso‡, and Linda Detwiler§
, Lisa M. McShane†, Gianluigi Zanusso‡, and Linda Detwiler§
Table 1
Total number of older cattle with negative test results required to achieve 95% or 99% confidence* that sporadic cases of BSE are not present at a level higher than the illustrated prevalence rates†
| Maximum prevalence | Log10 prevalence | No. tested cattle | |
|---|---|---|---|
| 95% Confidence | 99% Confidence | ||
| 1 per million | –6.000 | 2,995,731 | 4,605,168 |
| 1 per 2 million | –6.301 | 5,991,463 | 9,210,338 |
| 1 per 3 million | –6.477 | 8,987,195 | 13,815,508 |
| 1 per 4 million | –6.602 | 11,982,928 | 18,420,678 |
| 1 per 5 million | –6.699 | 14,978,660 | 23,025,849 |
| 1 per 6 million | –6.778 | 17,974,392 | 27,631,019 |
| 1 per 7 million | –6.845 | 20,970,124 | 32,236,189 |
| 1 per 8 million | –6.903 | 23,965,857 | 36,841,359 |
| 1 per 9 million | –6.954 | 26,961,589 | 41,446,529 |
| 1 per 10 million | –7.000 | 29,957,321 | 46,051,700
*α = 0.05 or 0.01. *α = 0.05 or 0.01. |
*α = 0.05 or 0.01.
†The required number of tests, all of which must be negative, is given by log (α)/log (1-prevalence); BSE, bovine spongiform encephalopathy.
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