TABLE 6.
Number of animals from control herds and vaccinated herds included in each shedder category according to IS900 and ISMap02 PCR results, grouped according to their combined results from conventional methods
| Group and results (shedder category, CT value) in IS900 and ISMap02 PCRa | No. (%) of animals (n = 615) with result using conventional methodsb |
Total | |
|---|---|---|---|
| Negative | Positive | ||
| TC | |||
| 0, >40 | 196 (61.44) | 36 (11.29) | 232 (72.73) |
| 1, >35 | 31 (9.72) | 27 (8.46) | 58 (18.18) |
| 2, 31–≤35 | 4 (1.25) | 10 (3.13) | 14 (4.39) |
| 3, ≤31 | 0 | 15 (4.7) | 15 (4.7) |
| All positives (1 to 3) | 35 (10.97) | 52 (16.3) | 87 (27.27) |
| Total | 231 (72.41) | 88 (27.59) | 319 |
| VH | |||
| 0, >40 | 209 (70.61) | 22 (7.43) | 231 (78.04) |
| 1, >35 | 12 (4.05) | 29 (9.8) | 41 (13.85) |
| 2, 31–≤35 | 1 (0.34) | 18 (6.08) | 19 (6.42) |
| 3, ≤31 | 0 | 5 (1.69) | 5 (1.69) |
| All positives (1 to 3) | 13 (4.39) | 52 (17.57) | 65 (21.96) |
| Total | 222 (75) | 74 (25) | 296 |
IS900 and ISMap02 real-time PCR results are from month zero. TC, test and cull control group; VH, vaccinated herd; 0, nonshedder; 1, low shedder; 2, intermediate shedder; 3, heavy shedder.
The conventional methods used were conventional PCR, fecal culture, and ELISA, performed during 5 years of sampling; animals were considered positive when positive to at least one of the conventional methods in any of the 5 annual samplings, and the rest were considered negative. Conventional method results were used as the reference to estimate the follow-up sensitivity and specificity of the triplex PCR. Follow-up specificity was 84.85% for the TC group and 94.14% for the VH group. Follow-up sensitivity was 59.09% for the TC group and 70.27% for the VH group.