TABLE 1.

Prevalence of the E. coli O157-specific rfbE gene and STEC virulence genes stx₁, stx₂, and eaeA among 16 ORG and 9 LIC dairy herds^a

Herd and parameter	Prevalence of gene (product)
	rfbE	stx1 (Shiga toxin 1)	stx2 (Shiga toxin 2)	eaeA (intimin)
ORG	+
	+		+
	+	+	+	+
			+
	+	+	+	+
		+	+	+
	+
	+	+	+
		+
	+	+	+	+
	+		+
	+	+	+	+
		+	+
	+
		+		+
		+	+
Prevalence	0.61	0.61	0.67	0.39
90% CI	0.42-0.79	0.42-0.79	0.48-0.83	0.21-0.58
Modusb	3	1	3	1
LIC		+	+	+
		+	+
	+	+	+	+
	+	+	+
		+	+
	+	+	+	+
		+	+	+
Prevalence	0.36	0.73	0.73	0.45
90% CI	0.15-0.61	0.49-0.91	0.49-0.91	0.22-0.70
Modusb	3	1	2	2
Total prevalence	0.52	0.67	0.70	0.41
90% CI	0.36-0.67	0.51-0.81	0.55-0.84	0.26-0.56
Modusb	3	1	2	1

^a+ indicates presence, as determined by Taqman PCR of the rfbE gene (E. coli O157) and STEC virulence genes stx₁, stx₂, and eaeA. Prevalence and associated 90% CIs are based on the binomial distribution, modeled in @Risk software.

^bModus of the number of positive pooled samples (maximum is 3).