Medical Microbiology Flashcards
infection
when a parasite is multiplying in/on a host (could have once been good bacteria, but the host is no longer benefitting)
infectious disease
the host cannot function normally due to presence of parasite or its products
pathogens
cause disease
pathogenicity
an organism’s ability to cause disease
virulence
degree or intensity or pathogenicity, as indicated by morbidity (sickness) and mortality (death) rates
three factors affecting the outcome of a host/parasite relationship
- number of organisms inoculated (usually more organisms = more risk)
- virulence of organism (some are so virulent it only takes a few to cause disease)
- host’s degree of resistance
incubation period
between inoculation and onset of signs and symptoms
prodromal stage
start to experience s&s (flu most contagious during this stage)
illness period
full intensity of s&s
convalescence
period of recovery (giardia most contagious during this stage)
iceberg theory of infection
most infections are subclinical, and would take an assay to detect (ex: herpes)
three factors affecting virulence of a microbe
- infectivity: ability of an organism to start an infection
- invasiveness: ability of organism to move within host
- pathogenic potential: ability of an organism to cause symptoms
infections
tissue damage caused by invasiveness of the microbe, or by toxins produced by the microbe in the host’s body
intoxications
damage due to toxins produced by the microbe outside the host’s body entering the host
exotoxins
proteins actively secreted by living microbes
