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Volume 12, Number 12—December 2006

Perspective

On the Question of Sporadic or Atypical Bovine Spongiform Encephalopathy and Creutzfeldt-Jakob Disease

Paul Brown*Comments to Author , Lisa M. McShane†, Gianluigi Zanusso‡, and Linda Detwiler§
Author affiliations: *Bethesda, Maryland, USA; †National Institutes of Health, Bethesda, Maryland, USA; ‡University of Verona, Verona, Italy,; §Virginia-Maryland Regional College of Veterinary Medicine, College Park, Maryland, USA

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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.
†The required number of tests, all of which must be negative, is given by log (α)/log (1-prevalence); BSE, bovine spongiform encephalopathy.

*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.

*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.

Main Article

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