E. coli O157 on Scottish cattle farms: Evidence of local spread and persistence using repeat cross-sectional data

Table 2 Single variate analysis of risk factors

Variable	Odds Ratio (95%CI)	p
Farm positive Survey 1	1.68 (1.00-2.83)	0.051
Farm in sampling cluster positive	2.97 (1.83-4.81)	<0.001
Season		0.162
Spring	1.52 (0.71-3.25)	0.277
Summer	2.23 (1.08-4.86)	0.298
Autumn	1.89 (0.90-3.95)	0.091
Winter	-	-
Animal Health Division		0.137
Island	0.21 (0.07-0.66)	0.008
Highland	0.75 (0.35-1.61)	0.460
North East	0.63 (0.29-1.35)	0.231
Central	0.61 (0.28-1.34)	0.215
South East	0.81 (0.43-1.84)	0.749
South West	-	-
Management: dairy	2.23 (1.26-3.96)	0.006
Management: beef cattle	0.57 (0.36-0.93)	0.023
Management: change	1.93 (0.98-3.80)	0.058
Pigs present	2.63 (0.92-7.45)	0.070
Farm size: large area (>100km²)	1.57 (0.97-2.56)	0.069
Farm size: farm area (km²)	1.93 (1.00-3.61)	0.040
Total number of cattle	3.85 (2.04-7.26)	<0.001
Farms within 1 km	1.53 (0.90-2.61)	0.120
Any movement^a (open vs closed)	2.54 (0.98-6.60)	0.057
Movement within 1 week of sampling	2.40 (1.24-4.64)	0.010
Movement within 2 week of sampling	2.01 (1.10-3.68)	0.023
Movement within 3 week of sampling	1.88 (1.07-3.32)	0.029
Movement within 4 week of sampling	2.24 (1.33-3.76)	0.003
Movement within 8 week of sampling	2.10 (1.29-3.41)	0.003
No. cattle moved within 4 weeks of sampling	2.94 (1.38-6.23)	0.005
No. cattle moved within 8 weeks of sampling	2.57 (1.41-4.68)	0.002
Arable agricultural^b	1.66 (0.90-3.08)	0.108
Any E. coli non O157 present	1.73 (1.06-2.80)	0.027

Variables identified from single variate logistic regression models for the presence of E. coli O157 on the 447 Scottish farms that were sampled in both Survey 1 (SEERAD, 1998-2000) and Survey 2 (IPRAVE, 2002-2004).
^a Movement (as defined by Cattle Tracing System (CTS) [20]) is deemed to have occurred when an animal is moved on to a specific farm or between herds.
^b Arable agriculture (Land Capability for Agriculture class 1-3.1). Prime agricultural land capable for being used to produce a wide range of crops. Favourable climate; slopes are no greater than 7 degrees; soils are at least 45 cm deep; imperfectly drained [21].

ISSN: 1746-6148