The capacity for a parasite/pathogen to cause disease.
The extent of disease caused upon infection (or infestation) by a parasite/pathogen is a function of parasite characteristics, host characteristics, and environmental concerns. A parasite's virulence takes into account all of these factors.
In evolutionary terms, virulence can be measured as decreases in host Darwinian fitness that is associated parasite/pathogen exposure. In addition, to the extent that virulence can vary among parasite genotypes – and generally it can vary a lot – then parasite virulence is a selectable trait, with virulence optima typically thought to be those which maximize parasite transmission rates to new hosts.
For more on this topic, see Wikipedia and Google. Contact web master. Return to home.