Purpose: This study used multilevel modeling to quantify farm-practice risks associated with the occurrence of E.coli O157:H7.
Methods: Fecal, water, sediments, and equipment swab samples were collected from cow/calf operations in Oklahoma and Louisiana, over a five-year period. Each farm was visited twice yearly. Collected samples were tested for E. coli O157:H7 using culture and molecular techniques. Farm practices were assessed using a questionnaire covering water source/container, cattle breed, herd density, type of feed, and farm-cleanliness (Likert scale of one to five). Associations between occurrence of pathogens and management practices was determined using a multivariable logistic regression model.
Results: In Oklahoma and Louisiana, E.coli O157:H7 was present in 1.8 and 11.7% fecal, 4.4 and 21% water, 7.2 and 46% sediments, and 1.7 and 15.2% equipment swab samples, respectively. The odds of detecting E.coli O157:H7 in feces was lower than in sediments, water troughs, and equipment swabs. This suggests horizontal transfer of pathogens between the studied variables. Modeling indicated that using surface water increased the odds-ratio (OR) of a farm being positive for E. coliO157:H7 by 3.12 times that of groundwater. The OR increased with herd density, but decreased on farms with a combination of pure- and crossbreeds compared to those with crossbreeds, only. The OR was lower for grain-feed than for hay/commercial feed. Among farm-cleanliness factors, OR increased for equipment (3.6), chute (1.1), and alleyway (1.5), when cleaned rarely compared to quite often.
Significance: Quantification of risks associated with farm practices may aid in developing efficient ways to manage pathogen occurrence and transmission.