A pathogen: any
microorganisms that has the capacity to cause disease.Virulence: a quantitative
measure of pathogenicity , or the likelihood of causing diseaseVirulence
factors: properties that enable a microorganisms to establish itself on or
within a host of a particular species and enhance its potential to cause diseasewhich regularly cause disease in some
proportion of susceptible individuals with apparently intact defense systems; e.g.,
Streptococcus pneumoniae, Staphylococcus aureus, Mycobacterium tuberculosis, SARS coronavirus, high-pathogenic
avian influenza virus A/H5N1which do not usually cause disease in people with
intact host defense systems, yet it can clearly cause devastating disease in
any hospitalized and immunocompromised patients; e.g., Pseudomonas aeruginosa, Acinetobacter baumannii
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