vs. 0.75 vs. 0.75 Testing Bulk Milk and Cheese Lots

155 Table : Impact of parameters of testing cheese lots on the risk per serving, relative to the risk per serving of baseline testing or pasteurized-milk cheese for Elderly population in Canada and the U.S. Alternative vs. Baseline Cheese lots testing Baseline: Baseline Test Canada U.S. Baseline: Pasteurized- milk cheese, no testing Canada U.S. Baseline dMedian 1 ref 1 ref dMedian 0.16 0.24 Baseline dMean 1 ref 1 ref dMean 0.08 0.13 125 g vs. 25 g dMedian 0.0005 0.0026 dMedian 0.0001 0.0006 125 g vs. 25 g dMean 0.0038 0.0047 dMean 0.0003 0.0006 1 Cheese vs. 5 Cheeses dMedian 0.58 0.69 dMedian 0.09 0.17 1 Cheese vs. 5 Cheeses dMean 0.77 0.72 dMean 0.06 0.10 Single L. monocytogenes detection probability: 0.50 vs. 0.75 dMedian 1.28 1.38 dMedian 0.21 0.33 Single L. monocytogenes detection probability: 0.50 vs. 0.75 dMean 1.51 1.37 dMean 0.12 0.18 Single L. monocytogenes detection probability: 0.90 vs. 0.75 dMedian 0.82 0.98 dMedian 0.13 0.24 Single L. monocytogenes detection probability: 0.90 vs. 0.75 dMean 0.86 0.96 dMean 0.07 0.13 In-plant env. L. monocytogenes contaminates: .5 vs. 2.5 dMedian 0.94 1.18 dMedian 0.15 0.28 In-plant env. L. monocytogenes contaminates: .5 vs. 2.5 dMean 1.11 1.08 dMean 0.09 0.14 In-plant env. L. monocytogenes contaminates: 1 vs. 2.5 dMedian 0.82 1.15 dMedian 0.13 0.28 In-plant env. L. monocytogenes contaminates: 1 vs. 2.5 dMean 1.10 1.22 dMean 0.09 0.16 95 cheese lots tested vs. 100 cheese lots tested dMedian 59 79.49 dMedian 9.68 19.2 95 cheese lots tested vs. 100 cheese lots tested dMean 24 23.83 dMean 1.94 3.20 90 cheese lots tested vs. 100 cheese lots tested dMedian 160 218 dMedian 26.1 52.7 90 cheese lots tested vs. 100 cheese lots tested dMean 44.4 46.9 dMean 3.57 6.31 ref: reference case. As well, Table 66 adds some precision to common-sense qualitative statements about testing protocols and the effect of testing on risk per serving at random. Particularly, testing i larger analytical samples 125 ml vs. 25 ml bulk milk; 125 g vs. 25 g cheese; ii with tests with higher sensitivity single L. monocytogenes detection probability 0.5, 0.75 0.9 for bulk milk or cheese lots; iii higher percentages of bulk milk or cheese lots 100 vs. 90 or 95; or, iv sample made from more than 1 cheese 1 cheese vs. 5 cheeses leads to smaller median and smaller mean risk per serving at random. As well, testing more effectively detects contaminated cheese lots that have higher within-lot contamination prevalence than contaminated cheese lots that have lower within-lot contamination prevalence. 156 -14 -12 -10 -8 -6 -4 -2 Pasteurized milk, Baseline Raw milk, Baseline Tested raw milk, Baseline Alternatives: tested raw milk: 125 ml vs 25ml Sensitivity test: 0.5 vs. 0.75 Sensitivity test:

0.9 vs. 0.75

95 of the milkings tested vs 100 90 of the milkings tested vs 100 Median risk per serving Mean risk per serving Median Reference Pasteurized milk Mean Reference Pasteurized milk Figure 23: Log 10 median ♦ and log 10 mean ■ risk per serving at random for the Elderly population, Canada, comparing pasteurized-milk soft-ripened cheese baseline, farmstead raw-milk cheese with farm bulk milk tested every milk collection and alternatives. See text for details. 157 -18 -16 -14 -12 -10 -8 -6 -4 -2 Pasteurized milk, Baseline Raw milk, Baseline Raw milk tested cheese lot Baseline Alternatives: 125 g vs 25g 1 cheese vs 5 cheeses Sensitivity test:

0.5 vs. 0.75