Chapter 1 Epidemiology Past and Present

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Chapter 1 Epidemiology Past and Present

• Epidemiology from Greek words
• epi, meaning on or upon,
• demos, meaning people, and
• logos, meaning the study of.

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• Epidemiology is the study of the distribution
  and determinants of health-related states or
  events in specified populations, and the
  application of this study to the control of
  health problems.
• Study Epidemiology is a scientific discipline,
  sometimes called the basic science of public
  health. It has, at its foundation, sound methods
  of scientific inquiry.

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Basic Definitions

• Health a state of complete physical, mental, and
  social well-being and not merely the absence of
  disease (WHO, 1948).
• Public Health Organized community effort to
  prevent disease and promote health

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Basic Definitions

• Illness what a person physiologically or
  psychologically experiences.
• Disease a medically definable physiological or
  psychological dysfunction.
• Sickness the state of dysfunction of the social
  role of a person with disease.

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Basic Definitions

• Morbidity events and factors associated with
  disease or disability.
• Mortality related to death.

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Basic Definitions

• Endemic disease and injuries occurring at a
  consistent rate
• Epidemic the occurrence of disease or injuries
  in clear excess of normalcy.
• Pandemic a epidemic that affects several
  countries or continents

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• Distribution. Epidemiology is concerned with the
  frequency and pattern of health events in a
  population.
• Frequency the number disease/injury events in a
  population and the rate or risk of disease in the
  population. Rates are critical for making valid
  comparisons across different populations.
• Pattern the occurrence of health-related events
  by time, place, and personal characteristics.

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• Time includes annual occurrence, seasonal
  occurrence, and daily or even hourly occurrence
  during an epidemic.
• Place includes geographic variation,
  urban-rural differences, and location of
  worksites or schools.
• Personal characteristics include demographic
  factors such as age, race, sex, marital status,
  and socioeconomic status, as well as behaviors
  and environmental exposures.

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Uses of Epidemiology

• 1. Historical study of the rise and fall of
  injuries and disease in a community. Can also
  produce projections.
• 2. Population or community health diagnosis or
  assessment (incidence, prevalence, etc.)
• 3. Study the workings of health services (needs,
  resources, service analysis)
• 4. Estimate the individuals chances or risks
  for injury and disease (age, race, behavior,
  etc.).

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Uses of Epidemiology

• Completing the clinical picture (e.g.,
  documentation of the numerous conditions that are
  associated with smoking).
• 6. Identify syndromes (A group of symptoms
  that collectively indicate or characterize a
  disease, psychological disorder, or other
  abnormal condition).
• 7. Search for causes - identifying factors
  which influence ones risk of disease, so that
  appropriate public health actions can be taken.
  (For example, withdrawal of tainted food from
  public consumption after epidemiology case
  studies).

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Epidemiologic Transitions

• Epidemiologic transactions focus on dramatic
  changes in morbidity and mortality in relation
  to
• Demographic
• Biological
• Socioeconomic factors

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Epidemiologic TransitionsChanges in 10 leading
causes of death per 100,000
2000 1. Heart Disease (246) 2. Malignant
Neoplasms (194) 3. Cerebrovascular Dis. (57) 4.
Lower Respiratory (43) 5. Accidents (36) 6.
Diabetes (25) 7. Pneumonia flu (22) 8.
Alzheimers 19 9. Nephritis (14) 10. Septicemia
(11)

• 1900
• 1. Pneumonia Flu (202)
• 2. Tuberculosis (194)
• 3. Diarrhea/gastrointest. (143)
• 4. Heart disease (137)
• 5. Inter-cranial lesions (107)
• 6. Nephritis (89)
• 7. Accidents (72)
• 8. Cancer and tumors (64)
• 9. Senility (50)
• 10. Diphtheria (40)

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Demographic Transitions
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Demographic Transitions
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Significant Historical Contributors

• Hippocrates
• John Graunt
• William Farr
• John Snow

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• Hippocrates (circa 400 B.C.) attempted to explain
  disease occurrence from a rational instead
• of a supernatural viewpoint. In his essay
  entitled On Airs, Waters, and Places,
  Hippocrates
• suggested that environmental and host factors
  such as behaviors might influence the
• development of disease.

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• John Graunt
• landmark analysis of mortality data in 1662
• quantify patterns of birth, death, and disease
  occurrence
• noting male-female disparities, high infant
  mortality, urban-rural differences, and seasonal
  variations
• William Farr
• systematically collect and analyze Britains
  mortality statistics.
• developed many of the basic practices used today
  in vital statistics and disease classification
• extended the epidemiologic analysis of morbidity
  and mortality data, looking at the effects of
  marital status, occupation, and altitude
• developed many epidemiologic concepts and
  techniques still in use today.

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• John Snow
• conducted studies of cholera outbreaks both to
  discover the cause of disease and to prevent its
  recurrence.
• descriptive epidemiology from hypothesis
  generation to
• classic study in 1854

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Early Epidemiological Beginnings

• Cholera Outbreak 1854
• Gathered data
• Generated hypothesis
• Intervened

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• What became of cholera?
• In the 20th Century, sanitary improvements have
  largely eliminated cholera from industrialized
  countries. Cholera remains endemic in many areas
  of the world, however. The seventh cholera
  pandemic that began in Indonesia in 1961
  continues. After a Peruvian outbreak in 1991,
  Central and South America saw more than one
  million cases and eleven thousand deaths through
  1995, and the disease also continues to produce
  significant morbidity and mortality in Africa and
  Asia.

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Demography

• Demography The study of births, deaths, and
  migration and how they influence population
  changes.
• The U.S. Census Bureau documents population
  changes in the U.S.
• Population pyramids describe distribution by age.

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America at the Dawn of a New Century

• POPULATION PROFILE OF THE UNITED STATES 2000

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Primary Data sources are

• The Decennial Censuses of Population and Housing
  (Census 2000 and earlier censuses)
• The Current Population Survey (CPS), and
• The Survey of Income and Program Participation
  (SIPP).

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Every state grew during the 1990s, but DC lost
population.
Source U.S. Census Bureau, Census 2000 and 1990
census.
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In Census 2000, 75 percent of respondents said
they were White alone.
Source U.S. Census Bureau, Census 2000.
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Between 1990 and 2000, the population aged 45 to
54 swelled 49 percent and those aged 85 and older
grew 38 percent.
Source U.S. Census Bureau, Census 2000 and 1990
census.
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Women outnumber men two to one in the group aged
85 and older.
(Number of men per 100 women by age)
Source U.S. Census Bureau, Current Population
Survey, March 2000.
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Almost one in five adults had some type of
disability in 1997 and the likelihood of having a
disability increased with age.
Source U.S. Census Bureau, Wave 5 (August -
November 1997) of the 1996 Panel of the Survey of
Income and Program Participation.
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Families still dominate American households, but
less so than they did 30 years ago.
Source U.S. Census Bureau, Current Population
Surveys, March 1970 and 2000
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Epidemiologic TransitionsChanges in 10 leading
causes of death per 100,000
2000 1. Heart Disease (246) 2. Malignant
Neoplasms (194) 3. Cerebrovascular Dis. (57) 4.
Lower Respiratory (43) 5. Accidents (36) 6.
Diabetes (25) 7. Pneumonia flu (22) 8.
Alzheimers 19 9. Nephritis (14) 10. Septicemia
(11)

• 1900
• 1. Pneumonia Flu (202)
• 2. Tuberculosis (194)
• 3. Diarrhea/gastrointest. (143)
• 4. Heart disease (137)
• 5. Inter-cranial lesions (107)
• 6. Nephritis (89)
• 7. Accidents (72)
• 8. Cancer and tumors (64)
• 9. Senility (50)
• 10. Diphtheria (40)