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  • Author or Editor: Jan M. Sargeant x
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Objective—To determine the distribution of Escherichia coli O157:H7 in pasture-based cattle production areas.

Sample Population—Two 100-km2 agricultural areas consisting of 207 pasture, 14 beef-confinement, and 3 dairy locations within 24 cattle operations.

Procedure—13,726 samples from cattle, wildlife, and water sources were obtained during an 11-month period. Escherichia coli O157:H7 was identified by use of culture and polymerase chain reaction assays and characterized by pulsed-field gel electrophoresis (PFGE).

Results—Odds of recovering E coli O157:H7 from feeder-aged cattle were > 4 times the odds for cowcalf or dairy cattle. There was no difference in prevalence for pastured versus confined cattle after controlling for production age group. Number of samples collected (37 to 4,829), samples that yielded E coli O157:H7 (0 to 53), and PFGE subtypes (0 to 48) for each operation varied and were highly correlated. Although most PFGE subtypes were only detected once, 17 subtypes were detected on more than 1 operation. Ten of 12 operations at which E coli O157:H7 was detected had at least 1 subtype that also was detected on another operation. We did not detect differences in the probability of having the same subtype for adjacent operations, nonadjacent operations in the same study area, or operations in the other study area.

Conclusions and Clinical Relevance—Strategies aimed at controlling E coli O157:H7 and specific subtypes should account for the widespread distribution and higher prevalence in feeder-aged cattle regardless of production environment and the fact that adjacent and distant cattle operations can have similar subtypes. (Am J Vet Res 2004;65:1367–1376)

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in American Journal of Veterinary Research


Objective—To describe the frequency and distribution of Escherichia coli O157:H7 in the feces and environment of cow-calf herds housed on pasture.

Sample Population—Fecal and water samples for 10 cow-calf farms in Kansas.

Procedure—Fecal and water samples were obtained monthly throughout a 1-year period (3,152 fecal samples from 2,058 cattle; 199 water samples). Escherichia coli O157:H7 in fecal and water samples was determined, using microbial culture.

ResultsEscherichia coli O157:H7 was detected in 40 of 3,152 (1.3%) fecal samples, and 40 of 2,058 (1.9%) cattle had ≥ 1 sample with E coli. Fecal shedding by specific cattle was transient; none of the cattle had E coli in more than 1 sample. Significant differences were not detected in overall prevalence among farms. However, significant differences were detected in prevalence among sample collection dates. Escherichia coli O157:H7 was detected in 3 of 199 (1.5%) water samples.

Conclusions and Clinical Relevance—Implementing control strategies for E coli O157:H7 at all levels of the cattle industry will decrease the risk of this organism entering the human food chain. Devising effective on-farm strategies to control E coli O157:H7 in cow-calf herds will require an understanding of the epidemiologic characteristics of this pathogen. (Am J Vet Res 2000;61:1375–1379)

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in American Journal of Veterinary Research