Prevalence of Escherichia coli O 157 : H 7 in cow-calf herds in Kansas

Fecal samples from cows and calves and samples of water sources were collected monthly for 8 months from 10 Kansas cow-calf farms to determine the prevalence of E. coli O157:H7. The bacterium was found in 8% of fecal samples from cows that were within 24 hours of calving, 1.4% of fecal samples from cows which were not within 24 hours of calving, 1.4% of calf fecal samples, and 1.5% of water samples. E. coli O157:H7 was identified from at least one sample on all farms.


Introduction
Over the past decade, Escherichia coli prevalence of E. coli O157:H7 in cow-calf O157:H7 has emerged as a significant public herds in Kansas.health concern.Humans infected with this bacterium experience a range of illnesses, including severe bloody diarrhea, hemolytic uremic syndrome, and occasionally death.
Ten commercial cow-calf herds in Kansas Many cases of the disease in humans are participated in the study; five were large linked to consumption of contaminated beef (>300 cows) and five were small (<100 products.The food processing industry has cows).All herds had a spring calving prointroduced HACCP (Hazard Analysis Critical gram.Each farm was visited approximately Control Points) programs aimed at reducing once per month from Dec., 1996 to July, the risk of contamination of beef products 1997.At each visit, we collected fecal samwith pathogens, including E. coli O157:H7.
ples from 10% of the cows and a water Considerable interest exists in extending sample from all water sources available to the HACCP programs to the farm to further minimize the risk that E. coli O157:H7 will O157:H7.The cow-calf industry is generally Therefore, little is known about the frequency of E. coli O157:H7 in these animals.The objective of this study was to determine the

Experimental Procedures
cattle.After the start of the calving season, Figure 1 shows the prevalence of E. coli we also collected fecal samples from 10% of O157:H7 by farm.Although smaller farms the calves.We collected fecal samples from tended to have a higher prevalence, the 50 cows that were within 24 hours of calving, difference was not significant (P>.05).The 1277 cows that were not within 24 hours of prevalence was quite low on all farms (<4%), calving, and 418 calves.We also collected but every farm in this study had at least one 135 water samples.
The fecal and water samples were tested infection is present to some degree on many for E. coli O157:H7 using standard culture farms.This has implications for control techniques, which included immunomagnetic programs but also suggests that producers separation and latex agglutination.
should use hygienic practices such as hand-

Results and Discussion
E. coli O157:H7 was isolated from 8.0% Figure 2 shows the prevalence of infecof the cows that were near calving, 1.4% of tion by month.The prevalence of E. coli the cows that were not near calving, 1.4% of O157:H7 was higher (P<.05) in March comthe calves, and 1.5% of the water samples.
pared to May and June.The graph indicates The presence of E. coli O157:H7 in water that infection was also more common in samples is of concern, because this might December.However, relatively few cattle spread the bacterium to uninfected cattle.
were sampled in December, so this rate was Prevalence did not differ (P>.05) between lence in March may be related to calving the types of samples, and tended to be higher patterns and not a true seasonal effect.The in cows near calving.majority of samples from cows near calving This suggests that, although the rate is low, washing after handling cattle and prior to eating.
not different (P>.05).The increased prevawere collected in March, and cows near calving tended to have a higher prevalence of E. coli O157:H7.