Table 2. Univariate exact conditional logistic regression analysis of potential exposures and risk factors for influenza A (H7N9) virus human infection — Zhejiang Province, China, 2013.

Exposures/risk factors*	Overall				Urban				Rural
	% exposed		OR	95% CI	% exposed		OR	95% CI	% exposed		OR	95%CI
	Case (n = 43)	Control (n = 215)			Case (n = 25)	Control (n = 125)			Case (n = 18)	Control (n = 90)
Buying live or freshly slaughtered poultry	42	11	7.9	3.0–23	48	12	8.9	2.6–39	33	8.9	6.6	1.3–42
Raising poultry at home or around the house	33	10	9.0	2.6–39	12	2.4	6.4	0.70–78	61	21	11	2.3–111
Tending to poultry	26	4.7	19	4.0–182	4.0	0.80	5.0	0.06–392	56	10	33	4.4–435
Existence of a poultry farm in vicinity of residence	16	2.8	13	2.4–133	8.0	0.80	10	0.52–590	28	5.6	16	1.6–788
Having neighbors that raised poultry at home	56	20	6.4	2.9–15	44	13	5.1	1.8–15	72	30	9.8	2.4–59
Presence of underlying medical conditions	65	22	7.1	3.2–17	76	13	30	7.0–272	50	18	4.7	1.4–19
Chronic obstructive pulmonary disease	24	0	31	4.2–∞	12	0	18	1.9–∞	11	0	11	0.84–∞
Cardiovascular disease	30	0	41	6.1–∞	16	0	21	2.6–∞	17	0	18	1.9–∞
Hypertension	54	13	8.1	3.1–24	56	11	23	5.1–215	28	16	2.6	0.60–12
Diabetes	33	3.7	5.7	1.6–23	24	2.4	11	1.9–117	11	4.4	2.1	0.17–20
Other diseases	39	0.55	61	9.8–∞	32	0	50	7.7–∞	11	1.1	9.7	0.75–∞
Smoking cigarettes	44	25	2.9	1.3–6.6	48	19	5.0	1.6–17	39	32	1.4	0.37–5.2

*The following exposures and factors were evaluated but were not statistically associated with disease onset: Slaughtering poultry, contact with dead poultry, visiting lake/park/pond/paddy field.