Source tracking swine fecal waste on household surfaces proximal to swine concentrated animal feeding operations in southeastern North Carolina, USA

Abstract

BACKGROUND AND AIM: In North Carolina, swine industrial livestock operations (ILOs) are located disproportionately in low-income and communities of color. Swine ILO neighbors have raised concerns about emissions from ILOs. We aim to compare the detection frequency and quantity of a swine-specific Bacteroides fecal microbial source-tracking marker (pig-2-bac DNA) contamination on outdoor and indoor household surfaces at ILO worker (ILO) compared to ILO neighbor (ILO-N) and metropolitan resident (metro) homes in North Carolina. METHODS: At enrollment, ILO, ILO-N, and metro participants collected 2 outdoor and 2 indoor household surface settled dust samples wiping a Copan flocked swab across a 10 cm2 area. Using quantitative real-time PCR, pig-2-bac DNA copy number per area was estimated in household samples. We used logistic and linear regression to evaluate differences in pig-2-bac prevalence and quantity between the three household groups and on outdoor compared to indoor surfaces. RESULTS: Ninety-one households (354 swabs) were sampled: 30 ILO (113 swabs), 31 ILO-N (119 swabs) and 30 metro (122 swabs). Prevalence of Pig-2-bac detection on >=1 household surface was 33%, 39%, and 0% among ILO, ILO-N, and metro households, respectively. Compared to metro households, higher log-10 pig-2-bac DNA copy number per 10 cm2 was observed at ILO (beta=0.5; 95% confidence interval [CI]=0.2, 0.7) and ILO-N households (beta=0.2; 95% CI=0.06, 0.4). Compared to indoor surfaces, higher log-10 copy number per 10 cm2S was observed on outdoor surfaces (beta = 0.181, 95% CI=0.02, 0.3). CONCLUSIONS: Swine-specific fecal contamination was detected at a higher prevalence in ILO-N compared to ILO workers and metro resident homes. Both ILO and ILO-N groups had statistically significant increases in copy number compared to the metro group. KEYWORDS: microbial contamination, pig-2-bac, industrial livestock operations, concentrated animal feeding operations