VIRULENCE + SUSCEPTIBILITY = INFECTION
Pathogen - Microbe that causes infection Pathogenicity - Ability of a microbe to cause infection Virulence - Meanture of pathogenicity in a susceptable host Virulence factor - Gene products that enables colonization of a susceptable host
Host suceptability is important in the balance between infection and no infection
Normally virulence = host defences so no infection is present
Low virulence can still cause infection when there is lowered host defences
High virulence can overwhelm the body and cause infection even in normal defences
Also the pathology of a pathogen can be caused by virulence factors or the host overreacting.