Table 4. Estimated numbers of exposed individuals and subclinical carriers, the mean exposed dose and the threshold estimates in bID50 for vCJD infection [43], and the expected numbers of vCJD cases exceeding the threshold dose based on the Weibull and Frechet extreme-value distribution fittings separately, assuming that the contamination rate is 
.
| Birth cohort | Number of exposed individualsa | Number of subclinical carriers | Mean exposure doseb | Extreme value distribution | Parameter estimates | Threshold dose estimate | Predicted vCJD cases | Observed vCJD casesc | |||
| MM | MV | VV | |||||||||
| α | σ | ||||||||||
| Pre-1970 | 7,020,967 | 5,368 | 3,575 | 7,153 | 0.18 | Weibull | 1.2 (1.1–1.3) | 1.8 (1.4–2.1) | 12.6 (10.8–16.4) | 64 (50–81) | 65 |
| (6,603,616–7,678,196) | (5,044–5,874) | (3,358–3,913) | (6,723–7,828) | Frechet | 1.6 (1.3–2.0) | 0.016 (0.003–0.047) | 10.0 (9.6–10.5) | 66 (51–83) | |||
| 1970–1979 | 1,681,722 | 2,643 | 1,763 | 0 | 0.16 | Weibull | 1.1 (1.0–1.2) | 1.7 (1.4–2.0) | 69 (53–87) | 69 | |
| (1,588,184–1,837,774) | (2,493–2,892) | (1,663–1,930) | (0–0) | Frechet | 1.2 (1.0–1.5) | 0.009 (0.001–0.029) | 71 (55–88) | ||||
| 1980–1989 | 1,265,595 | 2,428 | 0 | 0 | 0.11 | Weibull | 0.6 (0.4–0.7) | 0.3 (0.1–0.4) | 40 (28–55) | 40 | |
| (1,185,741–1,400,092) | (2,272–2,689) | (0–0) | (0–0) | Frechet | 1.1 (0.9–1.4) | 0.004 (0.000–0.011) | 42 (30–57) | ||||
| 1990–1996 | 312,619 | 7,848 | 12,560 | 3,144 | 0.06 | Weibull | 1.7 (0.6–4.8) | 0.3 (0.04–1.2) | 0 (0–0) | 0 | |
| (288,591–351,776) | (6,103–10,224) | (9,690–16,455) | (2,418–4,128) | Frechet | 1.2 (0.9–1.8) | 0.002 (0.000–0.015) | 1 (0–4) | ||||
| Total | 10,280,903 | 18,287 | 17,898 | 10,297 | Weibull | 173 (131–223) | 174 | ||||
| (9,666,132–11,267,838) | (15,912–21,679) | (14,711–22,298) | (9,141–11,956) | Frechet | 180 (136–232) | ||||||
The numbers in parentheses are the corresponding 95% confidence intervals.
a
The number of exposed individuals are for all genotypes who were alive at the end of 2013.
b
The mean exposure dose is obtained by dividing the estimated ratio of consumption of total amount of infectious dose in bID50 for each birth cohort by the corresponding number of exposed individuals who were alive at the end of 1996.
c
The three cases infected through blood transfusion are excluded [1].