Fecal Pollution, Public Health, and Microbial Source Tracking

Abstract

This chapter defines the problems associated with fecal pollution (with special attention to gastroenteritis), and describes some of the different uses of source tracking tools. It briefly describes the methods commonly used in source identification, and establishes the link between source tracking and food-borne and waterborne illnesses. The chapter discusses the impact accurate identification has on microbial risk assessment and in the implementation of risk management strategies. Fecal contamination of waters can be assessed in public health terms and economic terms. Most of the bacterial, viral, and protozoan pathogens associated with waterborne outbreaks are commonly found in the feces of higher mammals; hence, preventing mammalian fecal contamination of source water and recreational waters is critical to human health. Cryptosporidium parvum, which is the most identified human pathogen of the genus, is often isolated from multiple hosts. In addition, a limited number of environmental isolates are often obtained as part of waterborne and food-borne outbreaks, limiting the amount of source typing that is performed. Many waterborne outbreaks are associated with water ingestion during recreational activities. Food-borne illnesses are also associated with pathogens of fecal origin. In fact, many of the etiological agents are the same for food-borne and waterborne outbreaks. Public health and environmental protection officials have recognized the importance of discriminating between sources of fecal pollution for several decades. Potential applications of microbial source tracking (MST) have been driving methods development, and we currently find ourselves with multiple library-dependent and library-independent approaches in various stages of development and validation.