Proceedings of the Vertebrate Pest Conference

Routes that cattle become exposed to and contaminated with Escherichia coli O157 remain enigmatic. To ascertain the potential role of wild birds, particularly European starlings, in the transmission of Escherichia coli O157:H7 among dairy farms, the ecology of this pathogen in these birds was studied. Bird movement from roost sites to farms was monitored using radio-telemetry (n = 49). Concurrently, frequency of livestock feed contamination and E. coli O157:H7 carriage in birds and in cattle was ascertained. Most of the birds tagged from farms in the limited geographic region roosted communally at a location within 20 km of the farms where they were tagged. Individual birds returned frequently to the same farm on a daily basis for feeding. E. coli O157:H7 was cultured from approximately 3% of starlings and 4% of cattle in the study population. We have previously reported the isolation of indistinguishable molecular subtypes of E. coli O157 from starlings from different farms. Clearly, European starlings can serve as a vehicle to disseminate this pathogen from farm to farm. What remains to be determined is the magnitude of the contribution that birds have in the overall ecology of E. coli O157 in livestock populations, and how this might be mitigated.