Environmental and Adaptive Changes Necessitate a Paradigm Shift for Indicators of Fecal Contamination

Changes in the occurrence, distribution, and seasonal variation of waterborne pathogens due to global climate change may increase the risk of human exposure to these microorganisms, thus heightening the need for more reliable surveillance systems. Routine monitoring of drinking water supplies and recreational waters is performed using fecal indicator microorganisms, such as Escherichia coli, Enterococcus spp., and coliphages. However, the presence and numbers of these indicators, especially E. coli and Enterococcus spp., do not correlate well with those of other pathogens, especially enteric viruses, which are a major cause of waterborne outbreaks associated with contaminated water and food, and recreational use of lakes, ponds, rivers, and estuarine waters. For that reason, there is a growing need for a surveillance system that can detect and quantify viral pathogens directly in water sources to reduce transmission of pathogens associated with fecal transmission. In this review, we present an updated overview of relevant waterborne enteric viruses that we believe should be more commonly screened to better evaluate water quality and to determine the safety of water use and reuse and of epidemiological data on viral outbreaks. We also discuss current methodologies that are available to detect and quantify these viruses in water resources. Finally, we highlight challenges associated with virus monitoring. The information presented in this review is intended to aid in the assessment of human health risks due to contact with water sources, especially since current environmental and adaptive changes may be creating the need for a paradigm shift for indicators of fecal contamination.