Table 7.

The best-fit Accelerated Failure Time (AFT) model for the total infectious phase duration (threshold-defined and non-threshold approach) in cattle (Weibull distribution shape parameter = 4.49 for threshold and 3.86 for non-threshold), n is the number of animals in each category.

Variables	Category	n	Coefficient (β)	95% Cl	Time ratio	p-value
MODEL FOR THRESHOLD-DEFINED APPROACH
	Intercept		2.52	2.42 to 2.62		<0.0001
Serotype	O	26	−0.15	−0.30 to −0.002	0.9	0.0474
	Asia1	12	−0.05	−0.29 to 0.20	1.0	0.7177
	A	61	0
Exposure method 3	CTC	8	−0.16	−0.43 to 0.12	0.9	0.2622
	PTC	30	−0.07	−0.23 to 0.08	0.9	0.3506
	IDL	6	−0.22	−0.5 to 0.05	0.8	0.114
	SN	55	0
MODEL FOR NON-THRESHOLD APPROACH
	Intercept		2.71	2.6 to 2.82		<0.0001
Serotype	O	28	−0.11	−0.31 to 0.09	0.90	0.2916
	Asia1	12	−0.09	−0.42 to 0.25	0.92	0.614
	A	61	0
Exposure method 3	CTC	8	−0.30	−0.64 to 0.03	0.74	0.0764
	PTC	30	−0.09	−0.29 to 0.12	0.92	0.4018
	IDL	6	0.004	−0.54 to 0.54	1.00	0.9888
	SN	57	0