Pathogen risk refers to the danger presented by microorganisms that cause disease.
There is a clear evolutionary opportunity for a pathogenic or parasitic existence, living at the expense of nutrient-rich, warm, renewable hosts. These advantages are reflected by the number and variety of infectious organisms that are pathogenic to humans alone, with a comprehensive literature review identifying 1415 species (Taylor et al. 2001). These pathogens can be divided into five major taxonomic divisions: 15% are viruses (including prions), 38% bacteria (including rickettsia), 22% are fungi, 5% are protozoa, and 20% are helminths (Taylor et al. 2001). To further illustrate the appeal of a host environment, nonpathogenic bacteria (distinguished from pathogens by lack of host-damage) far outnumber human cells within our bodies (Rohmer et al. 2011). While nonpathogenic bacteria are tolerated by...
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