Current and future trends in fecal source tracking and deployment in the Lake Taihu Region of China

The emerging discipline of microbial and/or chemical source tracking (collectively termed fecal source tracking (FST)) is being used to identify origins of fecal contamination in polluted waters in many countries around the world. FST has developed rapidly because standard methods of measuring contamination in water by enumerating fecal indicator bacteria (FIB) such as fecal coliforms and enterococci do not identify the sources of the contamination. FST is an active area of research and development in both the academic and private sectors and includes:
• Developing and testing new microbial and chemical FST methods.
• Determining the geographic application and animal host ranges of existing and emerging FST techniques.
• Conducting experimental comparisons of FST techniques.
• Combining direct monitoring of human pathogens associated with waterborne outbreaks and zoonotic pathogens responsible for infections among people, wildlife, or domesticated animals with the use of FST techniques.
• Applying FST to watershed analysis and coastal environments.
• Designing appropriate statistical and probability analysis of FST data and
• developing models for mass loadings of host-specific fecal contamination.This paper includes a critical review of FST with emphasis on the extent to which methods have been tested (especially in comparison with other methods and/or with blind samples), which methods are applicable to different situations, their shortcomings, and their usefulness in predicting public health risk or pathogen occurrence. In addition, the paper addresses the broader question of whether FST and fecal indicator monitoring is the best approach to regulate water quality and protect human health. Many FST methods have only been tested against sewage or fecal samples or isolates in laboratory studies (proof of concept testing) and/or applied in field studies where the “real” answer is not known, so their comparative performance and accuracy cannot be assessed. For FST to be quantitative, stability of ratios between host-specific markers in the environment must be established. In addition, research is needed on the correlation between host-specific markers and pathogens, and survival of markers after waste treatments. As a result of the exclusive emphasis on FIB by regulatory agencies, monitoring and FST development has concentrated on FIB rather than the actual pathogens. A more rational approach to regulating water quality might be to use available epidemiological data to identify pathogens of concern in a particular water body, and then use targeted pathogen monitoring coupled with very specific FST approaches to control the pathogens. Baseline monitoring of FIB would be just one tool among many in this example.