Abstract

Assessing the prevalence of pathogenic bacteria wild birds carry is important to understanding their role in disease transmission, especially in environments that bring these birds close to domestic livestock. Cloacal swabs from 243 wild birds from five dairy farms in Humboldt County, California (USA), were cultured for enteric bacteria between July 2002 and February 2004. Fecal swabs from 80 dairy cattle were also cultured for enteric bacteria to determine if the cattle and birds shared similar bacterial species, indicating possible transmission. Birds sampled included 34 European starlings (Sturnus vulgaris), 56 brown-headed cowbirds (Molothrus ater), 65 house sparrows (Passer domesticus), 29 white-crowned sparrows (Zonotrichia leucophrys), 16 Brewer’s blackbirds (Euphagus cyanocephalus), and 43 red-winged blackbirds (Agelaius phoeniceus). Among all birds, the most prevalent enteric bacteria were Escherichia coli (40%), Enterobacter spp. (19%), Citrobacter spp. (11%), Proteus spp. (8%), Pseudomonas spp. (6%), Klebsiella spp. (5%) and Yersinia spp. (5%). Escherichia coli (92%) was by far the most common bacterium cultured from cattle feces; followed by Citrobacter spp. (20%), Klebsiella spp. (11%) and Proteus spp. (11%). Preliminary analysis indicates that bacterial species composition varied more among cattle on different farms than among bird species on different farms, although birds carried a wider range of enteric bacteria than cattle. Furthermore, few bacteria were shared between birds and cattle. However, both birds and cattle carry potentially pathogenic bacteria at low prevalences.