Purpose: The aim of this study was to assess the association between biosecurity practices and the prevalence of STEC in livestock raised on diversified farms.
Methods: This study analyzes a subset of 14 farms that were part of a larger year-long cross-sectional study conducted from 2015 to 2016. Cattle, swine, and small ruminant fecal samples (n=503) were cultured for STEC and positive isolates were serogrouped. Each farm completed a survey that included questions regarding livestock health, biosecurity, and management practices. An overall biosecurity score was calculated from the farm survey. Based on the median (32 points), the biosecurity score was divided into high (range 32 to 45) or low (range 20 to 31). Logistic models were used to evaluate the association between a high or low biosecurity score and STEC presence, using generalized linear mixed models with farm as a random effect.
Results: STEC was found in 13.72% (69 of 503) of samples and on 57.14% (8 of 14) of farms. Livestock raised on diversified farms with higher levels of biosecurity were less likely to be STEC positive (odds ratio (OR): 0.19; 95% confidence interval (CI): 0.048, 0.76). Other significant factors included raising cattle (OR: 4.06; 95% CI: 1.43, 11.61); farming less than 42 acres (OR: 11.71; 95% CI: 2.43, 56.5); and farming for more than 15 years (OR: 9.97; 95% CI: 1.59, 62.1).
Significance: This study highlighted the need to further investigate potential food safety risks on diversified farms. Identification of strategies to reduce these risks will promote public and livestock health in this emerging agricultural industry.