Table 5.

Results of the multilevel analysis with farm-based characteristics (P < 0·10) as independent factors in relation to non-dairy sheep farm residents C. burnetii seroprevalence

Variable	Category	OR (95% CI)
Goat density (number of goats/km2 excluding own animals in a 5-km radius)	<2·9	Reference
	2·9–11·3	1·60 (0·75–3·43)
	⩾11·4	3·80 (1·67–8·65)
Year farm started	Before 1990	Reference
	1990 or later	3·97 (1·79–8·82)
Blessumer breed present on farm	Yes	5·19 (2·36–11·41)
	No	Reference
Cattle at same pasture but not simultaneously with sheep	Yes	5·14 (2·17–12·19)
	No	Reference
How often bedding in stable is refreshed	Every other day or more	3·24 (1·49–7·07)
	Once or twice a week	Reference
	No stable	8·91 (2·17–36·68)
Air enters stable through door	Yes	0·46 (0·23–0·92)
	No	Reference
	No stable	8·91 (2·17–36·68)
Dairy cattle present during stabling period of sheep	Yes	3·33 (1·17–9·46)
	No	Reference
Lambing outside	Yes	0·34 (0·14–0·86)
	No	Reference
Sheep supplied from Groningen	Yes	4·17 (1·59–10·97)
	No	Reference
Sheep supplied from Noord-Holland	Yes	3·93 (1·74–8·90)
	No	Reference

OR, Odds ratio; CI, confidence interval; QIC, quasi-likelihood under the independence model criterion.

Number of observations used: 212. Number of levels used: 107 (QIC = 232·9560).