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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]
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a) relative severity and malignancy <ameliorate the \virulence of a disease>
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n.
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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.