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23 Cards in this Set

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Define epidemiology
The study of when and where diseases occur and how they are spread
Worldwide, __% of all deaths are due to infectious disease
30
Define incidence
the fraction of population that contracts the disease during a time period
Define prevalence
The fraction of population having symptoms of the disease during a specific time period
What are the five frequency levels of disease?
sporadic
endemic
epidemic
pandemic
outbreak
Define endemic
continual occurence at low level
Define epidemic
sporadic elevated levels, and low level continual
Define pandemic
widespread epidemic
What are the four types of human reservoir?
symptomatic
convalescent
acute carrier
chronic carrier
Define convalescent
recovering from the disease, but still infectious
Define acute carrier
in the incubation period which precedes development of symptoms
What are the four general types of reservoir?
human
animal
insect
inanimate
Define zoonose
A disease that occurs primarily in animals but can be transmitted to humans
What do bubonic plague and rabies have in common?
they are both zoonoses
What are the four modes of transmission?
contact transmission (via direct contact, ie skin pathogens)
common vehicle transmission (via fomites such as food, water, blood, drugs)
airborne (via droplets or dust)
vector (via living agents)
What are two measures of virulence?
infectious dose
lethal dose
How is lethal dose usually measured?
LD50 = number of bacteria required to kill 50% of pop'n
What is infectious dose?
number of bacteria required to produce disease
S. typhimurium inject intravenously has LD50 of ___. Orally the LD50 is ___.
10. 5,000,000.
Define 'endogenous nosocomial infection'
infection acquired in hospital as result of normal flora
Define 'exogenous nosocomial infection'
transmitted infection from other individual in hospital
Define 'iatrogenic nosocomial infection'
doctor induced infection
Iatrogenic nosocomial infections can result from what?
surgery
invasive diagnostics
medical implants