Purpose: To determine the prevalence of Salmonella, E. coli O157, and non-O157 STECs in cattle housed at CAFOs in the southwest desert, and in wild birds and rodents that frequent those CAFOs. We also examined movement patterns of wildlife to determine if they could transfer pathogens from the CAFO to nearby leafy green fields, thereby posing a risk to human health.
Methods: We collected fecal samples from cattle (n = 300), wild birds (n = 383) and rodents (n = 775) each season from summer 2013 to winter 2014. Cattle feces were collected from pen floors. Wild birds and rodents were live-captured, tagged, and swabbed to collect fecal material. Wild birds were fitted with radio transmitters and rodents with ear tags to determine movement between animal and vegetable production areas. Pathogens were isolated by pre-enrichment followed by IMS (STECs), selective plating, and PCR confirmation.
Results: CAFO cattle show a significant peak in the prevalence of Salmonella (16.5%), E. coli O157 (52.5%) and non-O157 STEC (17.0%) during fall compared to spring and summer (P = 0.019). Rodents and birds trapped at the CAFO do not show a significant seasonal difference in pathogen prevalence, but movement data do indicate that birds traveled regularly between the CAFO and produce fields.
Significance: Rodents at CAFOs likely pose a minimal pathogen risk to nearby fresh produce fields. However, birds have a greater home range and travel regularly between feeding and roosting sites. There is a need for practical and cost-effective approaches to co-manage agriculture with the surrounding natural environment.