European Starlings (Sturnus vulgaris) challenged with Escherichia coli O157 can carry and transmit the human pathogen to cattle

Abstract

European starlings (Sturnus vulgaris) are an invasive species in the United States and are considered a nuisance pest to agriculture. The goal of this study was to determine the potential for these birds to be reservoirs and/or vectors for the human pathogen Escherichia coli O157:H7. Under biosecurity confinement, starlings were challenged with various doses of E. coli O157:H7 to determine a minimum infectious dose, the magnitude and duration of pathogen shedding, and the potential of pathogen transmission among starlings and between starlings and cattle. Birds transiently excreted E. coli O157:H7 following low-dose inoculation; however, exposure to greater than 10(5.5) colony-forming units (CFUs) resulted in shedding for more than 3 days in 50% of the birds. Colonized birds typically excreted greater than 10(3) CFU g(-1) of faeces, and the pathogen was detected for as long as 14 days postinoculation. Cohabitating E. coli O157:H7-positive starlings with culture-negative birds or 12-week-old calves resulted in intra- and interspecies pathogen transmission within 24 h. Likewise, E. coli O157:H7 was recovered from previously culture-negative starlings following 24-h cohabitation with calves shedding E. coli O157:H7. European starlings may be a suitable reservoir and vector of E. coli O157:H7. Given the duration and magnitude of E. coli O157:H7 shedding by European starlings, European starlings should be considered a public health hazard. Measures aimed at controlling environmental contamination with starling excrement, on the farm and in public venues, may decrease food-producing animal and human exposure to this pathogen.