= Virulence
<Virulence> is the degree to which a <pathogen> causes damage or <disease> in a specified <host> and setting. It is a quantitative aspect of pathogenic behaviour, not simply a label meaning that an <organism> can cause an <infection>.<Virulence in MeSH by the National Library of Medicine>[Definition and indicators]{ref}
A comparison needs an endpoint and controlled conditions. One experiment might compare tissue damage after equal exposure; another might compare survival across a range of doses. If two <strains> differ in the dose required to produce an outcome, that result concerns the tested <host>, route and conditions. It is not automatically a universal ordering for every <species> or exposure route.
This also separates damage from transmission. A <pathogen> can spread efficiently without causing the most severe <disease>, while a damaging infection need not transmit efficiently. Keeping the outcomes separate makes evolutionary and experimental claims about <virulence> testable.
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