FOODBORNE PATHOGENS AND DISEASE Volume 3, Number 4, 2006 © Mary Ann Liebert, Inc. Review Listeria monocytogenes in Multiple Habitats and Host Populations: Review of Available Data for Mathematical Modeling RENATA IVANEK, 1 YRJÖ T. GRÖHN, 1 and MARTIN WIEDMANN 2 ABSTRACT Listeria monocytogenes has the ability to survive and multiply in diverse habitats and to cause infection in a va- riety of animal species and humans. We evaluated the literature on survival and multiplication within and trans- mission among multiple host populations and habitats, including man, sewage, general environment (soil, water, and vegetation), silage (fermented plant material), animals (including wild and domestic animals), and food pro- cessing plants. The available knowledge on L. monocytogenes transmission dynamics was translated into the key process nodes of interrelated host- and habitat-specific mathematical models, providing a starting framework for future modeling work and the ultimate development of a system-wide model for evaluation of its transmission, and strategies to reduce human exposure. Because of the ability of L. monocytogenes to survive and multiply in many habitats and hosts, and the number of possible transmission routes, it is highly unlikely that it could be eradicated from any habitat or host, including man. However, L. monocytogenes load within and transmission among habitats and host populations could probably be reduced. Based on the published information, we hy- pothesize that three recent anthropogenic practices increase the load within and transmission among reviewed habitats and host populations: extended refrigerated storage of ready-to-eat foods allowing L. monocytogenes growth in foods that are contaminated during production or subsequent handling; feeding domestic ruminants with silage often contaminated with L. monocytogenes; and dispersal of contaminated products of sewage treat- ment to agricultural fields and waters. Future mathematical modeling work could test how much the reduction of L. monocytogenes load and transmission in hosts and habitats associated with these anthropogenic practices would reduce human exposure and consequently human listeriosis. 319 INTRODUCTION L ISTERIA MONOCYTOGENES is an ubiquitous gram-positive bacterium associated with potentially serious invasive diseases in humans and a variety of animal species (Seeliger, 1961). L. monocytogenes has the ability to multiply in diverse habitats and is capable of surviving in adverse conditions for longer than many other nonsporing bacteria (Fenlon, 1999; Mitscherlich and Marth, 1984). It is transmitted among host species and habitats through multiple routes (Fenlon, 1999). The ecology and transmission of this pathogen are very complex and pre- vention of infection of mammalian hosts, in- cluding man, is challenging. Mathematical modeling provides a useful approach in the study of complex phenomena (de Jong, 1995). While the development of mathematical models for the survival, multi- plication, and transmission of L. monocytogenes would certainly aid in designing effective mea- 1 Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York. 2 Department of Food Science, Cornell University, Ithaca, New York.