Short-sighted evolution and the virulence of pathogenic microorganisms.

For some microorganisms, virulence may be an inadvertent consequence of mutation and selection in the parasite population, occurring within a host during the course of an infection. This type of virulence is short-sighted, in that it engenders no advantage to the pathogen beyond the afflicted host. Bacterial meningitis, poliomyelitis and AIDS are three candidates for this model of the evolution of virulence.