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.