Epidemiological studies on Escherichia coli O157:H7 in Egyptian sheep.

In the present work, the epidemiological role of apparently healthy sheep in transmission of Escherichia coli O157:H7 in different seasons was investigated. Fecal samples (convenience sampling) of apparently healthy farmed sheep (three farms, n = 70) and from 15 wandering flocks fed on city wastes (n = 80) in the Giza governorate were examined. The samples were collected in spring under mild weather conditions and during hot summer to be compared. Out of the 150 animals, 13 (8.7%) were E. coli O157 shedders. The 13 ovine sorbitol-negative E. coli O157 were characterized by different PCR sets. The eae gene was detected in 11 isolate (85%), stx1 in 3 isolates (23%), stx2 in 8 isolates (62%), and finally the hlyA in 11 isolate (85%). Among the 13 isolates, 2 strains (15%) were positive for eae, stx1, stx2, and hlyA as gene combination, one isolate (8%) for eae, stx1, and hlyA, 5 isolates (38%) for eae, stx2, and hlyA, 1 isolate (8%) for eae and stx2, 2 isolates (15%) contained eae and hlyA, 1 isolate (8%) contained hlyA only, and finally, 1 isolate (8%) did not contain any of these genes. None of the isolates showed the gene combination eae stx1, stx1 hlyA, or stx2 hlyA. The results indicated significant association of unfavorable weather and management conditions on O157:H7 shedding while the age or sex did not play any role in this process.