Concepts of Disease Occurrence and the Natural History and Spectrum of Disease Flashcards
agent
referred to an infectious microorganism or pathogen a virus bacterium, parasite or other microbe, chemical and physical causes of diseas
basically anythiing that can couse disease
pathogenicity
ability to cause disease
host
the human who can get the disease
environment
extrinsic (external) factors that affect the agent and the opportunity for exposure
physical factors (geology and climate)
biologic factors (insects that transmit the agent)
socieconomic factors
Causal pies WHO? WHEN?
Rothman 1976
causal pies
made up of component causes, when it comes together you can get a disease
the complete pie
called a causal pathway or a sufficient cause
can have multiple causal pathways
necessary cause
appears in every pie or pathway, without disease does not occur
Natural history of disease
refers to the progression of a disease process in an individual over time, IN THE ABSENCE OF TREATMENT
Step 1 in Natural History
exposure to accumulation of factors
Step 2 in Natural History of a Disease
Incubation/Latency Period
- pathological changes without the individual being aware
- the time of exposure to onset of disease symptoms
incubation period is for
infectious disaeses
latency period for
chronic diseases
What is Step 3 in Natural History
Onset of Symptoms
- transition from subclinical to clinical disease
- most diagnoses are made during this stage
spectrum of disease
the severity of disease mild to severely fatal
3 possible endings of a disease
- recovery
- disability
- death
Infectivity
proportion of exposed persons who became infected
pathogenicity
proportion of infected individuals who develop clinically apparent disease
virulence
the proportion of clinicaly apparent cases that are severe or fatal
carriers
people who are infectious but have subclinical disease are called carriers
Asymptomatic , passive, or healthy
those who never experience symptoms despite being infected
incubatory carriers
those who can transmit the agent during the incubation period before clinical illness begins
convalescent carriers
those who have been recovered from their illness but remain capable of transmitting to others
Chronic carriers
those who continue to harbour a pathogen for months or even years after their initial infection
Hosa id
1022111755
