Table 4: Cox’s proportional hazard regression model for persistence of M. bovis over three different sampling periods (Fall/Winter “A”, Winter/Spring “B” and Spring/Summer “C”) or seasons.

Risk factorParameter estimateStandard errorHazard ratio (95% confidence interval)

Season A−2.130.490.12 (0.05–0.32)
Season B−1.940.490.14 (0.5–0.38)
Season C0
Sample Type−0.280.160.76 (0.55–1.05)
Sterilized−0.500.350.61 (0.31–1.20)
Shade−0.680.330.51 (0.26–1.05)