tutorial 1 Flashcards
Endemic
– (a disease or condition) regularly found among particular people or in a certain area.
Epidemic
a widespread occurrence of an infectious disease in a community at a particular time.
Classification of epidemiological studies
Qualitative- and quantitive
Qualitative
descriptive and usually small in a group of people, information-rich
quantitive
aims to collect large information from people, reperesents general population.
descriptive and comparative
descriptive
: describe patterns of disease in variables, people, place and time descriptive purposes. Example Case report.
comparative
comparing a control group constitute the analytical study approach. Assess the effect, risk factors, therapy. Has 2 types quality control research and analytical research
Different forms of transmission of organisms
direct and indirect transmission
direct transmission
: direct spread from person to person from carrier; ex asymptomatic an genetic carrier
indirect transmission
: spread of infection through intermediary sources. Ex. Faecal- oral
Infectivity
the ability of a pathogen to establish an infection
Virulence
the severity or harmfulness of a disease or poison.
• Pathogenicity
pathogenicity is the ability of an organism to infect a host and cause disease aggressiveness is the ability of the pathogen to invade and establish within the host,
Criteria of causation
strength of causation: the stronger the association
Biological gradient: the observation that the frequency of disease increases with the dose or level of exposure usually lends to a casual interpretation.
Lack of temporal ambiguity: establish the cause of disease
Specificity of association: if the disease is only associated with one factor
Experiment: a trial is conducted
Plausibility: the hypothesized casual effect makes sense in the context of current knowledge, it is more likely to be accepted.
Consistency of feelings: all hypothesized cause and effect relationship produced a similar result.
Coherence of evidence: the cause and effect coherence of data should not be in conflict with the general known facts of the natural history
Analogy:
strength of causation:
the stronger the association
Biological gradient:
the observation that the frequency of disease increases with the dose or level of exposure usually lends to a casual interpretation.
Lack of temporal ambiguity:
establish the cause of disease
Specificity of association:
if the disease is only associated with one factor
Experiment:
a trial is conducted
Plausibility:
the hypothesized casual effect makes sense in the context of current knowledge, it is more likely to be accepted.
Consistency of feelings:
all hypothesized cause and effect relationship produced a similar result.
Coherence of evidence:
the cause and effect coherence of data should not be in conflict with the general known facts of the natural history
Analogy
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Reproductive rate
: transmission probability x contact per week x duration to infectivity
• Herd immunity
the resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, especially through vaccination.
Incubation period
: time interval from exposure to an infectious agent to the onset of the symptoms of an infectious disease
Induction period:
time interval between exposure and pathological onset
Latency period
the time from exposure to casual agents to onset of symptoms of a (usually non-infectious) disease
calculation of vaccination rate
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