Seroprevalence and Risk Factors of Chlamydia abortus Infection in Tibetan Sheep in Gansu Province, Northwest China

Table 4

Odds ratios for ages, seasons, and geographical origin of Tibetan sheep are taken as risk factors for Chlamydia abortus seroprevalence in Tibetan sheep.

Factor	Category	Tested numbers	Positive numbers	Prevalence (%)	OR (95% CI)	value
Region	Tianzhu County	962	157	16.32	Reference
	Maqu County	588	133	22.62	0.91 (0.56–1.48)	0.694
	Luqu County	182	33	18.13	1.40 (1.07–1.84)	0.014
Season	Winter	375	48	12.80	Reference
	Spring	480	89	18.54	1.67 (1.08–2.57)	0.022
	Autumn	479	98	20.46	1.78 (1.21–2.62)	0.003
	Summer	398	88	22.11	1.97 (1.33–2.91)	0.001
Age (yr)	0 < yr ≤ 1	335	25	7.46	Reference
	1 < yr ≤ 2	392	62	15.82	2.48 (1.51–4.07)	<0.001
	2 < yr ≤ 3	194	38	19.59	2.99 (1.72–5.19)	<0.001
	yr > 3	811	198	24.41	4.02 (2.58–6.26)	<0.001