When does the presence of a pathogen lead to disease? What will the
infection outcome be?
Virulence of the pathogen
Infectious dose
Virulence factors
Opportunity to infect the host
Successful transmission
successful colonization
body location
Persistence of the pathogen
Successful growth
Immune system evasion
Immune status of the host
Immunocompromising agents and conditions
probiotics & commensals
vaccines
Intervention strategies
antimicrobial treatment
prevention
Links in the infectious disease process and corresponding capabilities of a
pathogen
Colonization: Temporary or permanent growth of a microorganism in a
host
Infection: The inappropriate growth of a microorganism (pathogen) in the host body
Disease: A state of functional disequilibrium (bodily dysfunction)
Infectious disease: A disease that results from the presence of a
microorganism in the host body; can be transmitted to/from the host
Strict pathogen: A pathogen that always causes disease
when present
Opportunistic pathogen: A normally harmless microbe that
causes disease when the normal balance between the host immune system and
the microbe is altered. Often these are resident microbes.