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Epidemiology
- Basic science concerned with the patterns
- of disease frequency in human population
- • Distribution of disease by person, place,
- time
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Definition of Epidemiology
- epi = upon
- – demos = the people
- – ology = study of
- • Literally - “study of epidemics”
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Definition of Epidemiology
- The study of the distribution and
- determinants of health-related states or
- events in specified population, and the
- application of this study to control of health
- problems.
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Epidemiology Study
- surveillance, observation, hypothesis testing,
- analytic research, and experiments.
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Epidemiology Distribution:
analysis by time, place, and person
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Epidemiology Determinants
- physical, biological, social, cultural,
- and behavioral factors that influence health.
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Epidemiology Health-related states or events
- diseases,
- causes of death, behavior, reactions to preventive
- regimens, and provision and use of health services.
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A disease is an___when it occurs in an unusually
large number of people in a population at the same time
epidemic
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A___is widespread, usually worldwide
pandemic
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An___disease is constantly present in a population,
usually at low incidences
endemic
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The___of a particular disease is the number of new
cases of the disease in a given period of time
incidence
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The____of a disease is the total number of new and
existing cases in a population in a given time
prevalence
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A disease___occurs when a number of cases of a
disease are reported in a short period of time
outbreak
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Diseased individuals who show no or mild symptoms
have____
subclinical infections
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Subclinical individuals are called___
carriers
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____is the incidence of death in a population
Mortality
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------of a disease refers to the incidence of disease including fatal and nonfatal diseases
Morbidity
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Infection
- the organism invades and colonizes the
- host
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Incubation period
- the period of time between
- infection and onset of symptoms
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Acute period
the disease is at its height
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Decline period
disease symptoms are subsiding
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Convalescent period
- patient regains strength and
- returns to norma
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Preventable Causes of Disease
BEINGS
- Biological factors and Behavioral Factors
- • Environmental factors
- • Immunologic factors
- • Nutritional factors
- • Genetic factors
- • Services, Social factors, and Spiritual factors
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Epidemiology is used in clinical medicine to:
- describe the natural history of diseases
- • discuss disease causality
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proximate
biological mechanisms of disease
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distal
social and environmental causes of disease
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The Black Plague
- • 1330’s, outbreak of plague in China.
- • Spread to Italy and the rest of Europe
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Edward Jenner
- developed a vaccine against smallpox using cow
- pox
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John Snow
- described the association between dirty water and
- cholera
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Ignaz Semmelweis
- described the association between childbed fever
- and physician’s unclean hands
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James Lind
- conducted an experiment which showed that
- scurvy could be treated and prevented with limes,
- lemons, and oranges
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Joseph Goldberger
- identified that pellagra was not infectious but
- nutritional in origin and could be prevented by
- increasing the amount of animal products in the
- diet and substituting oatmeal for corn grits
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Reservoirs
Pools of infectious agents
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Saprophytic pathogens
reservoir is inanimate (e.g., Tetanus)
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Living reservoirs (animate
- disease can be eradicated
- (human-human vs. human-animal-human)
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Zoonosis:
- A disease that occurs primarily in animals but can
- be transferred to human (e.g., Plague [Yersinia pestis], bird
- flu, prions)
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Indirect transmission:Vectors:
- live organisms (e.g., arthropods, rodents); alternate
- hosts
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Indirect transmission Fomites:
inanimate objects (toys, contaminated needles)
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Pathogen eradication
- Efficient approach when the reservoir is infected
- hosts and when a highly efficient vaccine or
- drugs are available
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What Is Bioterrorism?
- The intentional use of micro-organisms or
- toxins derived from living organisms to
- produce death or disease in humans,
- animals, or plants
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Bacillus anthracis
- Easy to produce and deliver
- • Safe to the deploying party
- • Consistent killers i.e., efficient and predictable
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