Review of fecal pathogens in roof animals to model health risk of rainwater harvesting

The practice of collecting precipitation from rooftops (roof runoff) is an environmentally friendly way to supplement water supplies. One of the barriers to implementation of roof runoff in the US is limited risk-based treatment guidance for the use of roof runoff. Guidance is limited due to sparse information, environmental factors, roof runoff infrastructure, as well as the variability of pathogen characteristics (infection rate, prevalence, intensity, and virulence). A method for the estimation of health risks associated with roof runoff, is to assume there is a direct relationship between the pathogens in roof runoff and the pathogens in the feces of animals on rooftops. To expand the application of this method a literature review was conducted by searching for the terms “pathogens” and “feces” on Web of Science and by filtering for animals that frequently accessed rooftops. Included in the review are relevant articles referenced in articles from the Web of Science search. The most studied roof animals were birds, followed by cats, rodents, marsupials, insects, bats, racoons, and reptiles. The most studied pathogens were Salmonella, Escherichia coli, and Cryptosporidium. The prevalence of pathogens in animal populations was highly variable with Escherichia coli (0-96% of population infected) having a higher prevalence followed by Salmonella (0-48% of population infected) and Cryptosporidium (0-33% of populatios infected). In future work a meta-analysis will be conducted on the data from the literature review to validate the method and to conduct a more robust risk assessment. This work will hopefully aid in the development of treatment guidance for roof runoff.