Environmental pathogen hazards reveal need for improved sanitation infrastructure in Alabama's Black Belt

Olivia August Harmon , Megan E.J. Lott, Mark Elliott, Emily McGlohn, Joe Brown

Many rural communities in Alabama’s Black Belt region lack adequate sanitation resulting in wastewater discharges that may pose risks to residents. To understand the scope of the problem in one community, we conducted three cross-sectional surveys in a small town with limited sanitation in 2023. We measured a range of enteric pathogens in environmental samples by multi-parallel qPCR as well as fecal indicator bacteria E. coli and Enterococcus by culture and molecular methods. We examined soil samples (n = 55)  from sites near failing septic systems or suspected direct surface discharges and comparison soil (n = 10) far from potential discharges to estimate sanitation-related pathogen hazards. We examined surface water samples from community (n = 8) and localized (n = 16) sites that may have been impacted by wastewater discharges. Comparing impacted and unimpacted soils samples revealed greater fecal contamination near known or suspected discharges, compared with control samples. The mean culturable E. coli count in impacted soils was 224 MPN/g (95% CI 0-510.5 MPN/g) and in unimpacted soils was 0.5 MPN/g (95% CI 0-1.5 MPN/g).We detected several pathogens via qPCR in impacted soil and surface water, including Acanthamoeba spp., Balantidium coli, Blastocystis spp., Cryptosporidium spp., and rotavirus. In community-level surface waters (n = 8), 88% of samples were positive for E. coli by culture (mean 3.04 x 105, 95% CI 0-8.96, x 105 MPN/100mL ); 100% were positive for Enterococcus by culture (mean 1.10 x 104, 95% CI 0-2.55 x 104 MPN/100mL); and we detected Acanthamoeba spp., Blastocystis spp., Cryptosporidium spp., Plesiomonas shigelloides., rotavirus, and Yersinia enterocolitica, suggesting community-level wastewater discharges may degrade local surface water quality. Evidence suggests sanitation failures contribute to enteric pathogen hazards in this community, and culturable E. coli may provide a sensitive indicator of fecal contamination in prospective monitoring efforts.