TABLE 1.

Yersinia pseudotuberculosis in conventionally and organically produced pigs at farm level

Production type	Value for rectal swab samples
	n	No. (%) positive	95% CIa
			Random samplingb	Clustering at farmsc
Organic	121	23 (19)	12-27	5-48
Conventional (total)	243	6 (3)	1-6	0-14
High capacityd	125	6 (5)	2-11	0-27
Low capacitye	118	0 (0)	0-3	NCf
Total	364	29 (8)	6-12	2-21

^aCI, confidence interval.

^bNinety-five percent confidence interval of prevalence when sampling was assumed to be randomized (exact binomial estimates).

^cNinety-five percent confidence interval of prevalence when the fact that 21 to 26 pigs were sampled from each farm was considered (Fleiss quadratic 95% confidence interval).

^dProduction capacity of 1,000 fattening pigs or more per year.

^eProduction capacity of fewer than 1,000 fattening pigs per year.

^fNC, could not be calculated.