Table 7. Final model of herd-level risk factors associated with brucellosis sero-positivity among 681 herds which nested within 45 sites.

Variable code	Level	Odds ratio (95% C.I)	P-value
Strata	Stratum in which the investigations took place
	Periurban	1(Ref.)
	Urban	1.5(0.37–6.25)	0.334
	Rural	1.8(0.55–5.70)	0.557
Herd size	Number of animals in the herd
	< = 10	1 (Ref.)
	>10 and < = 50	1.9(0.71,5.15)	0.199
	>50	11.0(3.75,32.46)	<0.001
Abortion	Presence of females who aborted among the animals belonging to the herd surveyed
	No	1(Ref.)
	Yes	3.0(1.40–6.41)	0.005
Transhumance	Method of rearing animals of sedentary type (not migratory : No) or nomadic (transhumant : Yes)
	No	1(Ref.)
	Yes	5.4(2.84–10.41)	<0.001
Random effects		SE	95% CI
Site level variance	1.69	0.68	(0.77–3.72)

Legend: Ref.: reference group.