Exploration of risk factors contributing to the presence of influenza A virus in swine at agricultural fairs

Figures & data

Table 1 Summary statistics and crude odds ratios for presence of influenza A virus in pigs at fairs

	Flu (+)	Flu (–)	P value	Odds ratio	95% CI
Commercial swine population (×1000)	11.83	43.89	0.08	0.96	0.92–1.01
County population	202 255.7	70 490	0.71	1.00	0.99–1.01
Number of exhibitors	253.1	146.446	0.01	1.01	1–1.02
Number of pigs	407	217.5667	0.01	1.01	1–1.02
Length of exhibition	5.2	5.33	0.64	0.89	0.45–1.75
County fair attendance	129 180.2	80,175.79	0.52	1.00	0.99–1.01
Pig space (ft^2/pig)	13.5	12.56	0.15	1.13	0.87–1.48
Average daily mean temperature (°C)	24.22	20.67	0.03	1.32	1.01–1.75
	n	%	n	%	P value	Odds ratio	95% CI
Is there a breeding show in addition to the junior market show?
Yes	4	40	1	3.3	<0.001	43.5	4.1–461.79
No	6	60	29	97.7
Is there an operational hand-sanitizer or hand-wash station near the swine barn?
Yes	6	60	19	63.3	1	0.86	0.2–3.77
No	4	40	11	36.7
Is the junior market swine show terminal?
Yes	4	40	22	73.3	0.12	0.24	0.05–1.09
No	6	60	8	26.7
Open-class swine show in addition to the junior market show?
Yes	7	70	9	30.0	0.06	4.67	0.99–22.01
No	3	30	21	70.0
Sex requirements of junior market swine
Barrows only	0	0	3	10.0	0.56	N/A
Barrows and gilts	10	100	27	90.0
Showmanship occurs separate from the junior market show?
Yes	10	100	21	70.0	0.08	N/A
No	0	0	9	30.0
Pre-fair tag-in/weigh-in
Yes	4	40	19	63.3	0.27	0.39	0.09–1.67
No	6	60	11	36.7
Are any swine vaccines required?
Yes	0	0	1	3.3	1	N/A
No	10	100	29	97.7
Are there other pigs on the fairgrounds?
Yes	6	60	12	40	0.30	2.25	0.52–9.7
No	4	40	18	60

Table 2 Adjusted odds ratios from multivariable exact logistic regression model

	Adjusted odds ratio	P value	95% CI
Breeding show	21.676	0.005	2.417–∞
Number of pigs	1.012	0.012	1.002–1.026