Temporal and spatial patterns of bovine Escherichia coli O157 prevalence and comparison of temporal changes in the patterns of phage types associated with bovine shedding and human E. coliO157 cases in Scotland between 1998-2000 and 2002-2004

Table 1 Mean farm-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*	0.218 (0.141, 0.320)	0.205 (0.135, 0.296)	0.831
*By season*
Spring	0.222 (0.144, 0.325)	0.191 (0.125, 0.279)	0.614
Summer	0.230 (0.150, 0.335)	0.262 (0.177, 0.367)	0.637
Autumn	0.262 (0.173, 0.375)	0.231 (0.154, 0.330)	0.648
Winter	0.149 (0.094, 0.229)	0.130 (0.082, 0.199)	0.674
*By animal health district*
Highland	0.153 (0.096, 0.234)	0.198 (0.130, 0.289)	0.396
North East	0.248 (0.163, 0.359)	0.199 (0.130, 0.290)	0.442
Central	0.249 (0.164, 0.359)	0.204 (0.134, 0.296)	0.480
South West	0.189 (0.121, 0.283)	0.261 (0.177, 0.366)	0.257
South East	0.189 (0.166, 0.364)	0.231 (0.168, 0.354)	0.374
Islands	0.171 (0.108, 0.259)	0.111 (0.070, 0.172)	0.197
*By phage type*
PT2	0.033 (0.002, 0.352)	0.017 (0.008, 0.034)	0.857
PT8	0.011 (0.006, 0.020)	0.019 (0.01, 0037)	0.278
PT21/28	0.135 (0.067, 0.252)	0.124 (0.066, 0.219)	0.865
PT32	0.031 (0.0021, 0.378)	0.060 (0.019, 0.176)	0.779

ISSN: 1471-2180