Figure 3. Control program C applied in the Dordogne department between 2007 and 2010.

Step 1: yearly bTB screening using SITT (the herd being considered disease-free). All animals are tested (µ i,k Q(i,k) = 1). Sensitivity (Se) and specificity (Sp): those of SITT. Immediate transition to step 2 if an animal is positive (n^pos>0). Step 2: confirmation of SITT positive results using PDD γIFN (γIFN1) and ESAT-6 γIFN (γIFN2). All the positive animals of step 1 are tested (µ i Q(i,1) = 1. Sensitivity (Se) and specificity (Sp): parallel combination of both tests (positivity to any of both tests). Immediate transition to step 3 if an animal is positive; otherwise: transition to step 1. Step 3: interpretation of the positive results of step 2 as convergent (both γIFN tests are positive) or not (only one of both tests is positive). All the positive animals of step 2 (µ i Q(i,2) = 1) are concerned. Sensitivity (Se) and Specificity (Sp): sequential combination of both tests in positive animals of step 2. Transition to step 5 if an animal is positive, and to step 4 otherwise, two months later. Step 4: second confirmation of SITT positive results using PDD γIFN (γIFN1) and ESAT-6 γIFN (γIFN2). All the positive animals of step 1 are tested (µ i Q(i,1) = 1). Sensitivity (Se) and specificity (Sp): same as for step 2. Transition to step 5 if an animal is positive, two months later; otherwise: transition to step 1, 12 months later. Step 5: confirmation of SITT positive results using SICCT. All the positive animals of step 1 are tested (µ i Q(i,1) = 1), as well as 10% of the negative animals (µ i Q(i,0) = 0.1). Sensitivity (Se) and specificity (Sp): those of SICCT. Transition to step 6 if an animal is positive, three months later. Step 6: slaughter of SICCT-positive animals and isolation of M. bovis from lesions. All the positive animals of step 5 (µ i Q(i,5) = 1) are slaughtered (m = 1) and bacterial culture is performed from observed lesions. Sensitivity (Se): sequential combination of a visual inspection at the slaughterhouse and of a bacterial culture. Transition to step 7 if an animal is positive, 1 month later (Δt = 1 month). Step 7: total slaughter. All the animals (µ i,k Q(i,k) = 1) are slaughtered (m = 1). Routine detection of lesions at slaughterhouse. Sensitivity (Se_ev): sequential combination of a visual inspection at the slaughterhouse and of a bacterial culture. If a positive animal is thus detected, regardless of the current stage of control program, transition to step 7. See table 2 for the definition of the other parameters.