ABSTRACT
CONTENTS 1.1 Introduction ................................................................................................... 3 1.2 Molecular Subtyping and Public Health .................................................. 5 1.3 PulseNet USA................................................................................................ 7 1.4 PulseNet and the Concept of Strain Emergence ..................................... 8 1.5 Organisms Tracked by PulseNet................................................................ 9 1.6 PulseNet and Emergence of Foodborne Bacterial Pathogens ............. 13
1.6.1 Emerging Vehicles .......................................................................... 14 1.6.2 Travel ................................................................................................ 15 1.6.3 Changes in Public Health Practices:
The Good and the Bad................................................................... 16 1.6.4 Natural Disasters ............................................................................ 16 1.6.5 Discovering Hidden Outbreaks.................................................... 17
1.7 Next Generation Subtyping ...................................................................... 17 1.8 Concluding Remarks.................................................................................. 19 References ............................................................................................................. 21
Foodborne diseases cause an estimated 76 million illnesses each year in the United States with over 5.2 million of the infections attributed to foodborne bacterial pathogens (Mead et al. 1999). Of these, approximately 4.6 million infections are due to organisms currently tracked by the PulseNet system (Table 1.1). It is extremely important for the public health system to develop and implement new surveillance, outbreak detection, and response strategies geared toward reducing the number of foodborne illness in the United States and abroad (Spratt 1999; Swaminathan et al. 2001; Allos et al. 2004; CDC 2006c; Swaminathan et al. 2006). The future of foodborne disease control and prevention depends on the effectiveness and adaptability of
the surveillance and outbreak detection strategies in place, in particular, in an era where clusters of illness associated with less traditional vehicles of transmission are becoming more common (Tauxe 1998). In the modern outbreak scenario described by Tauxe (1997), the control of clusters of illness is complicated by the fact that cases tend to be diffuse in nature, often spanning multiple localities, states, regions, or even countries. This new outbreak scenario emerges amidst changes in the food industry geared toward improving efficiency in the preparation, processing, and distribution of food products in an expanding global market (Swerdlow 1998; WHO 2004). It is now common for foods to be prepared in central plants, packaged in a different locality, often under many different brand names or labels, and distributed across large communities, states, and often countries. Contamination of food products at the farm or during the early stages of processing could lead to the distribution of a tainted food product to any location in the country. Multiple locality outbreaks present a formidable challenge for epidemiologists in the United States and abroad in particular in development and implementation of strategies for the rapid detection of clusters of illness that would allow for rapid intervention and ultimately prevention of additional infections from occurring (Tauxe 1997; Sobel et al. 2002). Although identifying the source of infection is absolutely important in the control of an outbreak, it is also of great importance to gain insight on how foodborne pathogens persist in animal reservoirs, survive, and adapt to environmental changes, and how different processing and distribution practices may enhance their ability to enter the human food chain.
