Public toilets have reduced enteric pathogen hazards in San Francisco

Abstract

Uncontained fecal wastes in cities may present exposure risks to the public. We collected discarded feces from public spaces in San Francisco, CA for analysis by RT-qPCR for a range of enteric pathogens. Out of 59 samples, we found 12 (20%) were of human origin and 47 (80%) were non-human; 30 of 59 stools were positive for ≥1 of the 35 pathogens assessed, including pathogenic E . coli , Shigella , norovirus, Cryptosporidium , and Trichuris . Using quantitative enteric pathogen estimates and data on observed fecal waste from a public reporting system, we modeled pathogens removed from the environment attributable to a recently implemented program of public toilet construction. We estimated that each new public toilet reduced the annual number of enteric pathogens released into the immediate environment (within 500 m walking distance), including 6.3 x 10 12 enteropathogenic E . coli (95% CI: 4.0 x 10 12 –7.9 x 10 12 ), 3.2 x 10 11 enteroaggregative E . coli (95% CI: 1.3 x 10 11 –6.3 x 10 11 ), and 3.2 x 10 8 Shigella (6.3 x 10 7 –2.5 x 10 9 ). Improving access to public sanitation can reduce enteric pathogen hazards in cities. Interventions must also consider the hygienic disposal of animal waste to reduce microbial hazards with zoonotic infection potential.