Table 5.
Estimates of WHPapp threshold value ± asymptotic s.e. and approximate 95% confidence intervals for the detection of a MAP-positive herd using a combination of two, three or five environmental locations tested by FC, qPCR or the combination of both, respectively, at different probabilities of detection
| Single sampling | Double sampling | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| FCa | qPCRb | FC and qPCRc | FC | qPCR | FC and qPCR | |||||||
| Pdd (%) | WHPapp ± s.ee | 95% CIappf | WHPapp ± s.e. | 95% CIapp | WHPapp ± s.e. | 95% CIapp | WHPapp ± s.e. | 95% CIapp | WHPapp ± s.e. | 95% CIapp | WHPapp ± s.e. | 95% CIapp |
| Combination of two environmental samples (main alleyway, holding pen) | ||||||||||||
| 50 | 7·2 ± 1·2 | 4·7–9·6 | 5·7 ± 0·7 | 4·2–7·2 | 5·2 ± 0·8 | 3·7–6·7 | 7·2 ± 1·2 | 4·7–9·6 | 3·5 ± 1·1 | 1·3–5·7 | 3·5 ± 1·1 | 1·3–5·7 |
| 90 | 10·2 ± 2·6 | 4·9–15·4 | 7·9 ± 1·5 | 4·8–11·0 | 7·7 ± 1·6 | 4·5–10·8 | 10·2 ± 2·6 | 4·9–15·4 | 7·5 ± 2·0 | 3·4–11·5 | 7·5 ± 2·0 | 3·4–11·5 |
| Combination of three environmental samples (milking area, main alleyway, holding pen) | ||||||||||||
| 50 | 5·1 ± 0·5 | 4·2–6·1 | 4·9 ± 1·5 | 1·9–7·9 | 2·9 ± 1·0 | 1·0–4·9 | 5·1 ± 0·5 | 4·2–6·1 | 3·5 ± 1·1 | 1·3–5·7 | 2·9 ± 1·0 | 1·0–4·9 |
| 90 | 6·4 ± 0·9 | 4·6–8·2 | 10·9 ± 4·0 | 3·0–18·9 | 6·2 ± 1·6 | 3·0–9·4 | 6·4 ± 0·9 | 4·6–8·2 | 7·5 ± 2·0 | 3·4–11·6 | 6·2 ± 1·6 | 3·0–9·4 |
| Combination of five environmental samples (milking area, maternity, crossing to calf area, main alleyway, holding pen) | ||||||||||||
| 50 | 5·1 ± 0·5 | 4·2–6·1 | 4·1 ± 1·4 | 1·3–6·9 | 2·9 ± 1·0 | 1·0–4·9 | 5·1 ± 0·5 | 4·2–6·1 | 2·9 ± 1·0 | 1·0–4·9 | 2·9 ± 1·0 | 1·0–4·9 |
| 90 | 6·4 ± 0·9 | 4·6–8·2 | 9·9 ± 3·3 | 3·3–16·4 | 6·2 ± 1·6 | 3·0–9·4 | 6·4 ± 0·9 | 4·6–8·2 | 6·2 ± 1·6 | 3·0–9·4 | 6·2 ± 1·6 | 3·0–9·4 |
WHPapp, Apparent within-herd prevalence; s.e., standard error; MAP, Mycobacterium avium spp. paratuberculosis; FC, faecal culture; qPCR, quantitative real-time polymerase chain reaction; CI, confidence interval.
Herds classified as MAP-positive by testing environmental samples by FC.
Herds classified as MAP-positive by testing environmental samples by qPCR.
Herds classified as MAP-positive by testing environmental samples by using both qPCR and FC.
Probability of detection MAP-positive herds as positive.
Estimated threshold value of the WHPapp ± approximate s.e. for the detection of a MAP-positive herd.
Approximate 95% CI of the estimated threshold value of the WHPapp for the detection of a MAP-positive herd.