Table 4.

Herd, climate and individual cow parameters pre-selected (P < 0·25) for inclusion in EHEC modelling

Parameter	Level	n	OR*	95% CI	P value
Hygiene score	>2	5	0·53	0·199–1·409	0·203
	1 or 2†	23
Cow contact	Each unit increase	n.a.	0·971	0·958–0·984	<0·0001
Parity	⩾3	7	0·512	0·206–1·272	0·149
	2	6	0·572	0·219–1·495	0·255
	1†	15
Days in milk	Each day increase	n.a.	0·884	0·819–0·953	0·0014
Any disease or treatment	Any	10	1·758	0·761–4·06	0·187
	None listed†	18
Antibiotic or other treatment	Ever antibiotic	8	1·66	0·709–3·886	0·243
	Ever other	2	0·467	0·107–2·035	0·311
	None listed†	18
Average weekly temperature (°F)	Each unit increase	n.a.	1·06	1·027–1·093	0·0002
Average weekly humidity (%)	Each unit increase	n.a.	1·031	0·987–1·076	0·167
Weekly precipitation (inches)	Each unit increase	n.a.	1·19	0·91–1·54	0·21

EHEC, Enterohaemorrhagic E. coli; OR, Odds ratio; CI, confidence interval; n.a., not applicable.

^*Comparison odds of shedding EHEC.

^†Reference category.