Prevalence of Escherichia coli serogroups and human virulence factors in faeces of urban Canada geese ( Branta canadensis )

This was the first study to exhaustively characterize the prevalence of Escherichia coli sero-groups in any wildlife species. Faecal samples from Canada geese (Branta canadensis) were collected over a single year in Fort Collins, Colorado, USA. The overall prevalence for E. coli ranged from 2% during the coldest time of the year to 94% during the warmest months of the year. During the time of year when nonmigratory geese dominated the local goose population (March-July) the prevalence of enterotoxogenic (ETEC) forms of E. coli was 13.0%. The prevalence of enterohemorrhagic (EHEC) forms was 6.0%, while prevalence for enteroinvasive (EIEC) and enteroagglomerative (EAEC) forms was 4.6 and 1.3%, respectively, during the same period. We also examined all samples positive for E. coli for genes coding for virulence factors, including: SLT-I, SLT-II, eae, hly-A, K1, LT, STa, STb, CNF1, and CNF2. Three isolates were positive for human virulence factors, representing a 2% prevalence for faeces containing potential human toxins. Genes for STa were isolated from ETEC strains O-8 and O-167, while the gene for K1 was isolated from an O-8 (ETEC) serogroup. These data will prove useful in focusing attention on the risks that increasing populations of urban Canada geese pose to public health.