Table 2.

Mean pat-level prevalence of bovine E. coli O157 shedding for the SEERAD (March 1998-May 2000) and IPRAVE (February 2002-February 2004) surveys.

Category	Mean Prevalence (Lower, Upper 95% Confidence Limits)		P-value
	SEERAD	IPRAVE
All categories	0.089 (0.075, 0.105)	0.040 (0.028, 0.053)	<0.001
By season
Spring	0.104 (0.084, 0.126)	0.044 (0.024,0.0 66)	<0.001
Summer	0.084 (0.053, 0.118)	0.039 (0.022, 0.058)	0.018
Autumn	0.085 (0.061, 0.110)	0.045 (0.024, 0.069)	0.016
Winter	0.074 (0.035, 0.107)	0.030 (0.011, 0.054)	0.045
By animal health district
Highland	0.094 (0.044, 0.170)	0.023 (0.008,0.045)	0.034
North East	0.114 (0.075, 0.161)	0.024 (0.005, 0.050)	<0.001
Central	0.093 (0.068, 0.118)	0.033 (0.011, 0.058)	<0.001
South West	0.051 (0.030, 0.073)	0.068 (0.026, 0.133)	0.550
South East	0.106 (0.074, 0.139)	0.054 (0.022, 0.091)	0.030
Islands	0.064 (0.028, 0.108)	0.042 (0.013, 0.077)	0.396
By phage type
PT2	0.013 (0.008, 0.019)	0.004 (0.001, 0.007)	0.007
PT8	0.004 (0.001, 0.007)	0.004 (0.000, 0.009)	0.821
PT21/28	0.052 (0.039, 0.067)	0.019 (0.012, 0.028)	<0.001
PT32	0.010 (0.006, 0.014)	0.007 (0.003, 0.011)	0.262