Establishing Methods to Monitor Swine Fecal Contamination of Surface Water, Drinking Water, and Settled Dust in Communities Neighboring Swine Concentrated Animal Feeding Operations, Yucatán, Mexico, 2022

Background:
Yucatán, Mexico, has experienced an expansion of swine concentrated animal feeding operations (CAFOs). These operations produce large quantities of concentrated waste that may contaminate surrounding areas and infiltrate surface and groundwater. This pilot study explored the viability of swine fecal contamination testing across several impacted communities and was conducted to build local technical capacity and to address community complaints against the industry.

Methods:
Community and study team members collected well, surface, cenote (natural underground reservoir), and tap water samples in nine and settled dust samples from road signs, apiaries, and outdoor home surfaces in three Mayan communities in Yucatán. Samples were tested for the presence of the swine fecal source tracking marker Pig-2-Bac by quantitative PCR.

Results:
Challenges in shipping from Yucatán, Mexico, to Baltimore, USA, led to prolonged holding times of samples under suboptimal storage conditions. Nonetheless, Pig-2-Bac was detected in 4/21 well, 0/6 cenote, 0/1 tap, and 1/7 surface water samples. Among the settled dust samples, 1/2 road sign, 0/38 apiary, and 0/9 household surfaces tested positive for Pig-2-Bac, providing preliminary evidence of contamination of water and outdoor surfaces with swine fecal waste in multiple communities.

Conclusion:
Despite limitations in sample storage conditions, Pig-2-Bac was detected in multiple communities and media. These and future data can support indigenous Mayan communities and affected residents that are engaged in lawsuits against the CAFO industry. Capacity building and technological transfer of procedures to perform microbial source tracking would improve communities’ ability to expeditiously test environmental samples for pig fecal contamination.