So far, in genetic analysis the resolving power has been limited only by the refinement of techniques.
In the type of recombination on which classical genetic analysis is based, these structures are the chromosomes and their linearly arranged elements. The latter are recognized as genes as a consequence of their specific activities in metabolism and development (Pontecorvo, 1958).
Complete genome sequences are now available for multiple strains of several bacterial pathogens and comparative analysis of these sequences is providing important insights into the evolution of bacterial virulence. Recently, DNA microarray analysis of many strains of several pathogenic species has contributed to our understanding of bacterial diversity, evolution and pathogenesis (Fitzgerald & Musser, 2001).
Comparative genomics has shown that pathogens such as Escherichia coli, Helicobacter pylori and Staphylococcus aurues contain extensive variation in gene content whereas Mycobacterium tuberculosis nucleotide divergence is very limited. Overall, these approaches are proving to be a powerful means of exploring bacterial diversity, and are providing an important framework for the analysis of the evolution of pathogenesis and the development of novel antimicrobial agents (Fitzgerald & Musser, 2001).
It is of little relevance whether the agents of risk are organic or inorganic; their effects both relate to processes of 'contamination' and 'spreading'. They can both be understood as 'actors'. In the discourses that have brought viruses to our attention, pathogen motivation is of crucial importance. Viruses make us ill because they are replicating themselves; like waste, they are virulent objects of modernity. However, unlike waste, they 'take over' bits and pieces of our bodies because they are motivated by self-replication. That is, they borrow bits of genetic material (DNA or RNA) and ribosome from their hosts (Cann, 1997; Levine, 1992).
Popular culture can indeed be seen as playing a crucial role in the social and symbolic organization of risk management; expositions of newly emergent pathogen virulence have fully embraced the technological culture of the risk society. However, our exploration would not be able to escape the ironic turning-inward if it would merely circulate on the plane of textual analysis. Therefore, we turn to more sociological explanations of infections and epidemics to argue that pathogen virulence is part of a wider network of actors (humans, animals, technologies, and spirits). Moreover, it allows us to understand the social in terms of a complex spatialization of body politics and biopolitics, in which pathogen virulence constitutes a particularly effective medium of both 'sense-making' and the management of body boundaries (Joel Cracraft, Michael M. Miyamoto, 1991).
De Bary (1879) broad definition of symbiosis includes parasitism and disease, areas in which significant discoveries are being made. This has been most evident in bacterial pathogenesis. During the past decade, scientists have introduced innovative approaches and concepts from disciplines such as bacteriology,