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34 Cards in this Set
- Front
- Back
Define Prevalence
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Prevalence is the number of cases at a given time/population unit
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Define morbidity
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Morbidity is the number of new cases/time period/population unit
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Define mortality
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Mortality is the number of deaths/number with disease
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Define outbreak
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An outbreak is a small, localized increase in the occurence of a disease
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Define index case
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An index case is the first disease case in an epidemic within a give population
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Define endemic
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Endemic is the basal level of a disease (if the endemic is high it is refered to as hyperendemic)
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Define epidemic
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An epidemic is a significant increase in the frequency of a disease
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Define pandemic
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A pandemic is a global epidemic (crosses continents)
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Differentiate between signs and symptoms of an infectious diseas.
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Signs of an infectious disease are objective changes that can be observed/measured (fever, rash, weight loss), while symptoms are subjective changes experienced by the patient (pain, nausea).
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What are the five stages of a typical infectious disease?
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The five stages of a typical infectious disease are 1) Incubation, 2) Prodromal, 3) Acute, 4) Decline, and 5)Convalescent periods.
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During which stage is a disease usually contagious?
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A disease is most usually contagious during the prodromal and acute periods, although it is sometimes contagious in incubation and decline periods.
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What is a syndrome?
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A syndrome is a typical or diagnostic set of signs and symptoms.
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What are Koch's postulates?
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???
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How do the kinetics of propagated spread differ from common source epidemics?
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A propagated spread has a slow rise and a slow decline, while a common source epidemic has a sharp rise and a sharp decline.
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What is threshold density and what happens when the level is reached in a propagated epidemic?
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Threshold density is the minimum number of individuals necessary to continue propagating the disease. When threshold density is reached in a propagated epidemic the incidence of new cases ceases because the pathogen can not propagate itself.
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What are sources and reservoirs?
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A source is a location from which the etiologic agent is transmitted to the host. A reservoir is a habitat where the organism can reproduce and be a source for subsequent infections.
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What are examples of animate and inanimate reservoirs?
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An examples of animate reservoirs are animals (carriers). Examples of inanimate reservoirs are soil, water, etc.
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What is a carrier?
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A carrier is an infected individual that acts as a source.
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When is a disease a zoonose?
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A disease is a zoonose when it is carried by an animal and transmitted to humans.
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What constitutes airborne transmission?
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For transmission to be considered airborne the pathogen must travel in the air at least one meter.
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What are droplet nuclei?
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Droplet nuclei are small particles that represent what is left from evaporation of larger particles called droplets (they are airborne).
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What are examples of direct contact transmission?
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Examples of direct contact transmission (person to person) are sex and rabies (animal bite).
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What are fomites?
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Fomites are inanimate objects that transmit to host.
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Whay are aerosols listed under contact rather than airborne?
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Aerosols are listed under contact rather than airborne because they travel less than one meter.
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What are examples of "common vehicles"?
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"Common vehicles" are common inanimate intermediaries in the indirect transmission of an agent that carries the agent from a reservoir to a susceptible host. Two examples are food and water.
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Differentiate between mechanical and biological vectors.
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In mechanical vector transmission carriage of the pathogen is passive, which no growth during transmission (ex: flies). In biological vector transmission the vector acts as a reservoir where the pathogen grows (ex: mosquito).
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What is the apparent relationship between transmission rates and changes in virulence?
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There are two possible relationships between transmission rates and changes in virulence: Decreasing transmission rates favors decreased virulence-this appears true for cholera and bacillary dysentary, and
Increasing transmission rates favor increased virulence-this is hypothesized for the flu epidemic of 1918. |
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Give an example of how a pathogen can be induced to evolve increased virulence.
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A pathogen can be induced to evolve increased virulence if the spread of the disease is independent of host health/survival (ex: colds/gonorrhoea, syphillis)
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Give an example of how a pathogen can be induced to evolve decreased virulence.
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A pathogen can be induced to evolve decreased virulence if the spread of the disease is dependent upon host health/survival (ex: arthropod-borne diseases/diphtheria, tuberculosis)
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How do changes in transportation and the disruption of ecosystems contribute to the emergence of new diseases?
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???
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What are the three types of measures we use to control epidemics? Cite a couple examples for each.
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Three types of measures we use to control epidemics are 1)reducing or eliminating the source/reservoir (ex:quarantine, treatment of waste, destruction of animal reserve), 2) breaking the connection (ex: chlorination of water, pasteurization, destruction of vectors), and 3) increasing the herd immunity (ex: active and passive immunization).
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Why are biological agents effective for terrorists?
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Biological agents are effective for terrorists because they have small mass, are inexpensive, there is a delay from release to effect, the manufacture and dispersal can be low tech, and they have a strong psychological impact.
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What are the bacteria, viruses, and toxins most commonly associated with biowarfare?
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Some of the bacteria, viruses, and toxins that are most commonly associated with biowarfare are: Bacillus anthracisis, Yersinia pestis, Hemorrhagic viruses, Variola (smallpox virus), Botulinum toxin, and Staph. enterotoxin.
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What are three general strategies employed in defense against bilogical agents?
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Three general strategies employed in defense against biological agents are vaccines, drugs, and detection/intelligence.
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