Water Resources Research Act Program

Details for Project ID 2020HI313B

Fecal Indicators and Their Associated Health Risk in American Samoa's Watersheds

Institute: Hawaii
Year Established: 2020 Start Date: 2020-03-01 End Date: 2021-02-28
Total Federal Funds: $61,213 Total Non-Federal Funds: $73,646

Principal Investigators: Marek Kirs

Abstract: Shifts in rainfall driven by climate change are anticipated to affect watershed processes and water quality, hence there is a need for water monitoring programs that would be protective of human health under a wide variety of contamination and climate scenarios. This is especially important for small island communities which are most vulnerable to change. Currently, under the Watershed Management and Protection Program, none of the watersheds monitored in American Samoa supports recreational water use based on the pathogen indicator concentrations. The contamination appears to be from non-point sources, but is mostly not known. Recreational water quality in American Samoa, as in the US, is evaluated based on the microbial pathogen indicators (enterococci and Escherichia coli) which in many situations are not indicative of health risk, nor do they indicate the source of contamination. These organisms can originate from various animals, such as dogs and pigs, abundant in American Samoa. Also it has been hypothesized that these organisms can grow in tropical soils. The concentrations of these organisms in American Samoa soils have not been studied, and growth of those organisms in natural environments have not been conclusively demonstrated. While molecular methods to determine the contamination sources exist, these methods have not been utilized in American Samoa, and need to be validated for specificity and sensitivity based on the local animals before they can be used. As the health risk associated with different sources (humans, different animals, soils) is expected to vary, the health risk associated with microbial pathogen indicators needs to be established under different contamination scenarios. This would enable formulation and application of meaningful science based site-specific water quality standards. The overarching goal of this project is to improve surface water monitoring programs in American Samoa by validating methods capable of discriminating between contaminations sources and investigating the health risk association of pathogen indicators in selected watersheds on Tutuila island. To achieve this goal, we will: 1) determine pathogen indicator (enterococci and E. coli) and alternative pathogen indicator (Clostridium perfringens) concentrations in American Samoan soils, 2) conduct experiments to determine if these pathogen indicators can grow in American Samoan soils, 3) determine specificity and sensitivity of two human, one dog, and one pig associated test based on animal and sewage samples collected in American Samoa, and 4) investigate health-risk relationship of pathogen indicators by analyzing water samples from five water sheds for pathogen indicators and reference pathogens as well as conduct source-specific tests. We will use cultivation-based and molecular qPCR-based tests for pathogen indicators (enterococci, E. coli), alternative pathogen indicators (C. perfringens), source specific markers (targeting humans, dogs and pigs), as well as for a set of human pathogens responsible for 97% of water-associated illnesses. The study will be conducted in two tiers: first year the soil and microbial source tracking studies will be conducted in five watersheds ranging from pristine to extensive land-use, this will also include validation of two human, one pig, and one dog associated marker for specificity and sensitivity in American Samoa; second year health risk association of pathogen indicators will be determined using quantitative microbial risk assessment approach in the watersheds. It is field- and lab-work intensive study with limited amount of time budgeted for computer analyses and reporting. Substantial effort will be made to reach out and engage the community. Training will be provided for the ASCC student and a graduate assistant.