Table 3.

Odds ratios for H7N9 virus according to H9 virus and characteristics of the environment, Zhejiang province, China, March 2013–April 2015

Characteristics	H9(−)					H9(+)
	H7N9(−)	H7N9(+)	aOR	95% CI	P value	H7N9(−)	H7N9(+)	aOR	95% CI	P value
Area type
Urban	4871	227	1·00	Ref.		632	102	3·46	2·64–4·53	<0·001
Rural	9167	353	0·94	0·77–1·14	0·529	646	277	4·93	3·90–6·23	<0·001
Premise type
Live poultry  markets	8131	548	12·39	8·57–17·9	<0·001	1017	338	46·80	31·83–68·81	<0·001
Other premises	5907	32	1·00	Ref.		261	41	22·62	13·31–38·44	<0·001
Prefecture
Hangzhou	919	107	1·00	Ref.		78	46	2·94	1·87–4·61	<0·001
Huzhou	1151	166	1·00	0·74–1·35	0·988	83	118	6·86	4·61–10·21	<0·001
Jiaxing	1938	93	0·34	0·25–0·47	<0·001	39	15	2·66	1·3–5·44	0·007
Jinhua	2135	95	0·40	0·3–0·55	<0·001	348	143	2·36	1·72–3·22	<0·001
Lishui, Quzhou,  Taizhou	3385	97	0·17	0·12–0·23	<0·001	515	50	0·35	0·24–0·52	<0·001
Ningbo, Shaoxing,  Wenzhou, Zhoushan	4510	22	0·04	0·02–0·06	<0·001	215	7	0·28	0·12–0·63	0·002
Year
2013	2259	32	1·00	Ref.		199	0	0·00		0·995
2014	7987	292	2·58	1·77–3·76	<0·001	658	99	7·73	5·03–11·87	<0·001
2015	3792	256	5·77	3·93–8·48	<0·001	421	280	40·67	27·11–61·02	<0·001
Sample type
Poultry faeces	6168	187	1·00	Ref.		390	130	6·51	4·92–8·63	<0·001
Poultry cage swab	2927	142	1·80	1·41–2·3	<0·001	225	64	5·58	3·89–7·99	<0·001
Drinking water for  poultry	1418	38	2·00	1·37–2·91	<0·001	158	32	6·00	3·8–9·47	<0·001
Sewage from cleaning  poultry	1080	63	2·52	1·83–3·46	<0·001	160	51	9·63	6·49–14·28	<0·001
Swabs of tables for  slaughtering or  holding poultry	1499	105	2·00	1·54–2·62	<0·001	276	81	7·58	5·42–10·59	<0·001
Others	946	45	2·58	1·79–3·72	<0·001	69	21	26·15	13·6–50·26	<0·001

aOR, Adjusted odds ratio; CI, confidence interval.