Pathogen Risks Related to the Movement of Birds Frequenting Livestock and Fresh Produce Growing Areas in the Southwestern U.S.

Concentrated animal feeding operations (CAFOs) are sometimes located in close proximity to fresh produce fields, both of which serve as easily accessible food and water sources for wild birds. When birds travel between these two areas, they have the potential to transfer pathogens from cattle, a documented source of enteric zoonotic foodborne pathogens, to fresh produce crops through fecal deposition. However, the presence of pathogens in wild birds is not a risk unless the birds or their fecal material come into contact with fresh produce crops. Therefore, the objective of this study was to determine if birds visiting CAFOs use flyways that cross fresh produce fields, thereby increasing the risk for contaminating fresh produce intended for human consumption. During 2014, birds trapped at a CAFO in southern Arizona were fitted with Lotek nano-coded radiotransmitters. Two receivers were placed at the CAFO and two receivers were placed in nearby fresh produce fields. A total of 103 birds were fitted with radiotransmitters, including 66 red-winged blackbirds, 21 Eurasian collared doves, 11 brown-headed cowbirds, four common ravens, and one European starling. Over four million data points were collected indicating the date, time, and bird ID number for each time a bird was recorded within 1 km of a receiver. Radiotelemetry results showed that birds travel regularly between the CAFO and fresh produce fields. Using PCR and culture techniques, 2 (1.9%) birds tested positive for Salmonella, and 5 (4.9%) tested positive for non-O157 Shiga toxin-producing Escherichia coli (STEC). During the same time period, Salmonella (4%), STEC O157 (16%), and non-O157 STEC (44.5%) were detected in 400 cattle fecal samples from the CAFO. Our results will aid in determining the pathogen risks that birds pose to fresh produce when they are frequent visitors to a CAFO and fresh produce fields