- The ability of any agent of infection to produce disease. The virulence of a microorganism (such as a bacterium or virus) is a measure of the severity of the disease it is capable of causing. The adjective virulent implies extremely noxious, damaging, deleterious, disease-causing (pathogenic). Marked by a rapid, severe, and malignant course. Poisonous, venomous. The word “virulence” comes from the Latin “virulentia” from “virus” meaning a slimy liquid, particularly one that is foul and poisonous.
* * *The disease-evoking severity of a pathogen; numerically expressed as the ratio of the number of cases of overt infection to the total number infected, as determined by immunoassay. [L. virulentia, fr. virulentus, poisonous]
* * *a) relative severity and malignancy <ameliorate the \virulence of a disease>b) the relative capacity of a pathogen to overcome body defenses compare INFECTIVITY
* * *n.
* * *vir·u·lence (virґu-ləns) [L. virulentia, from virus poison] the degree of pathogenicity of a microorganism as indicated by the severity of the disease produced and its ability to invade the tissues of a host. It is measured experimentally by the median lethal dose (LD50) or median infective dose (ID50). 1. by extension, the competence of any infectious agent to produce pathologic effects.
Medical dictionary. 2011.