Table 1

Odds ratios for possible risk factors for detecting Salmonella Cubana on farms in the outbreak in pig farms in Sweden 2003.


Odds ratio (90% confidence interval)



Farm positive in feed and/or faeces (n = 49)
Farm positive in faeces (n = 31)

Type of production:


Integrated vs piglet
3.14 (1.09 – 9.02)
1.78 (0.61 – 5.15)
Fattening vs piglet
3.38 (1.11 – 10.28)
1.25 (0.41 – 3.83)
Herd size:


No. of pigs (OR per extra 100 pigs)
1.05 (1.00 – 1.10)
1.03 (1.00 – 1.06)
No. of stable units:


1–5 stable units vs ≥ 11
0.21 (0.05 – 0.85)
0.26 (0.08 – 0.83)
6–10 stable units vs ≥ 11
0.28 (0.06 – 1.29)
0.39 (0.11 – 1.42)
Herd size (divided on type of production):


Piglet producing


big vs small (<500 pigs)
17.50 (1.88 – 163.22)
9.33 (1.08 – 81.0)
Fattening


big vs small (<950 pigs)
0.33 (0.07 – 1.57)
0.30 (0.08 – 1.21)
Integrated


big vs small (<1250 pigs)
1.56 (0.46 – 5.34)
1.76 (0.54 – 5.74)
Type of feed:


soy vs other types
18.32 (3.20 – 104.90)
1.62 (0.68 – 3.85)
Feeding system:


dry vs wet (H2O)
0.92 (0.34 – 2.51)
0.60 (0.21 – 1.69)
wet (whey) vs wet (H2O)
2.50 (0.94 – 6.62)
0.93 (0.37 – 2.33)
wet (whey) vs dry
2.73 (1.02 – 7.29)
1.56 (0.60 – 4.07)
Feed delivery week:


(farms with only one delivery, n = 46)


18 vs 23
0.08 (0.01 – 1.22)
N.a.
19 vs 23
0.50 (0.06 – 4.03)
0.06 (0.01 – 0.45)
20 vs 23
0.21 (0.03 – 1.69)
0.08 (0.01 – 0.70)
21 vs 23
0.28 (0.03 – 2.37)
0.06 (0.01 – 0.52)
22 vs 23
0.22 (0.03 – 1.96)
0.13 (0.01 – 1.10)
No. of feed deliveries:


one vs three or more
1.13 (0.31 – 4.15)
0.35 (0.10 – 1.29)
two vs three or more
0.80 (0.20 – 3.25)
0.45 (0.11 – 1.83)
Amount of feed: (OR per extra ton)
1.04 (1.00 – 1.08)
1.02 (0.99 – 1.04)

Reference variables (baseline) in italics. Odds ratios with p < 0.10 in bold. N.a. = not applicable, due to too few observations in one group.

Österberg et al. Acta Veterinaria Scandinavica 2006 47:13   doi:10.1186/1751-0147-47-13