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.
Results—Escherichia 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)