The Kinetics of E.Coli O157:H7 from Feces to Soil and Ground Water, on a Dairy Farm Reared under Field Conditions in Baghdad Province and Its Relation to Public Health

Abstract

The aims of this study were to investigate the kinetics of E.coli O157:H7 from faces and its migration through soil into well- water, and the ability of E.coli OI57:H7 to persist on/in soil in Iraqi dairy farms reared under entirely different environmental conditions. The prevalence of E. coli O157:H7 in fecal, soil surface (Z1, Z5, and Z10) and depth (D0, D5 and D10) and well-water samples from January through May 2012 were determined. Colonies isolated from fecal, soil, and water samples with morphological characteristic of E.coli O157: H7 on CT-SMAC, CHROMagar, were further confirmed as E.coli O157: H7 by biochemical reaction, and subjected to agglutination reaction to identifying the O157 somatic and H7 flagellar antigens. Of 32 fecal samples collected over 4 weeks sampling period, 24 (75%) were positive for E.coli O157:H7. Of 63 soil samples collected during the period of the study 43 (68%) were positive for E.coli O157:H7 in all directions of the farm. The prevalence of E.coli O157:H7 contamination transferred to the interior of soil decreased with increased depths, this correlation is highly significant. A total of 45 well-water samples were collected during April and May, 23 (51%) were found to be E. coli O157:H7 positive. The highest prevalence was in April (63%) compared to May (33%). A total of 140 samples (fecal, soil, and water) were collected in this study, 90 (64%) were found to be E.coli O157:H7 positive. Fecal samples had higher prevalence (75%) than soil and water (68% and 51%) respectively. In conclusion, the results of this study demonstrated that E. coli O157:H7 can persist for extended periods of time in the faeces, soil, and well-water in the dairy farm reared under natural conditions. This is important because it suggests that these may contribute to the dissemination of E. coli O157:H7 on food products intended for human consumption.

Keywords: E.coli O157:H7, dairy farm, kinetics, environmental pollution, public health