Figure 2

Comparison of age-related changes in Peyer's patch (PP) development and estimated risk of TSE infection relative to the most susceptible age class, for sheep, cattle and humans. (A) PP areas for n = 19 Cheviot sheep of mixed genotypes in 3 age classes (left hand axis, open circles), compared with estimates of risk of scrapie infection relative to the most susceptible age class (solid line) (± 50 percentiles-dashed lines) from field data on n = 34 cases in mixed PrP genotype (VRQ/VRQ and VRQ/ARQ) Cheviot sheep (see Methods) in the same age classes (right hand axis). (B) PP tissue weight against age for n = 94 cattle (open points, data from ref. 18), compared with estimates of risk of BSE infection relative to the most susceptible age class (solid line) as a function of age made from n = 158,550 BSE cases in British cattle [5] (C) Numbers of PPs in the small intestine in 8 age classes of humans (open circles, data taken from ref. 19), compared with estimates of risk of vCJD infection relative to the most susceptible age class (solid line, ± 50 percentiles-dashed lines) from n = 129 vCJD cases in British people for the same age classes (redrawn from ref. 6).