Chapter 9 Pathogen Surveillance Through Monitoring of Sewer Systems

It is now possible to monitor sewage systems for pathogen occurrence in a community. An epidemiological approach to monitoring sewer systems is especially relevant for an early warning of pathogens used as biological weapons. In many situations, bioterrorist contamination events will result in the pathogen shedding to wastewater before a community level epidemic begins. Detecting the organism early allows the governments to respond on time and eliminate a potential catastrophe. A. Monitoring for human pathogens in sewage Monitoring of human pathogens in sewage is possible because they may be excreted in a range of bodily fluids, skin, and hair during active infection (Feachem et al., 1983). All of these materials will find their way into sewage systems during the process of waste elimination (toilet flushing) and cleaning (e.g., bathing, hand washing). In addition to release during active infection, pathogens can be washed into sewage systems from cleaning of indoor (floor washing, kitchen sink use) and outdoor (auto washing, driveway cleaning, storm water collection) facilities. Thus, sewer systems collect pathogens from over a wide area to a common carrier, where they are transported to a central facility for processing. Wastewater presents a time dynamic collection point where many physical, chemical, and biological substances of our society are brought to a central location. Monitoring of centralized wastewater allows detection of intentional, natural, or accidental contamination events. Because of recent bioterrorism concerns in the U.S., routine monitoring is potentially useful since it can result in better preparedness of utilities and the public health response system (Meinhardt, 2005). The qualitative microbial risk assessment (QMRA) framework can be used as a tool to develop and interpret this type of wastewater monitoring system. Because the threat level drives the risk assessment analysis, a monitoring system should be coordinated with findings from modeling studies on the survival and dispersion of contaminants (Kim et al., 2007, Romero et al., 2008, Sinclair et al., 2008), the contaminant point of introduction (Danneels and Finley, 2004), the health risk (Haas et al., 1999), and the locations of early warning systems/sensors in wastewater and water treatment systems (Murray et al., 2004). A recent U.S. National Research Council study called for more resilient design/operation of wastewater and drinking water systems (USNRC, 2007) to improve response and recovery from adverse water quality events in collection systems, water distribution systems, and water/wastewater treatment systems. Monitoring programs for pathogens or surrogates could potentially aid in the accomplishment of these goals. The aim of this review of published literature and reports is to assess the feasibility of monitoring sewage systems as an early warning system for the release of pathogens from an intentional, natural, or accidental biological contamination event. We address issues from a QMRA perspective and explore methods to detect and monitor pathogens in wastewater. The review presents our conclusions on: (1) the potential biological agents that might be released into a sewage system, (2) the likely background level of those agents in sewage, (3) laboratory methods and detection, and (4) the probability of detecting select biological agents in sewage.