Often called “the cornerstone” of public health, epidemiology is the study of the distribution and determinants of diseases, health conditions, or events among populations and the application of that study to control health problems. By applying the concepts learned in this course to current public health problems and issues, students will understand the practice of epidemiology as it relates to real life and makes for a better appreciation of public health programs and policies. This course explores public health issues like cardiovascular and infectious diseases – both locally and globally – through the lens of epidemiology.
Pioneers of Epidemiology (History continued)
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Из курса от партнера The University of North Carolina at Chapel Hill
Epidemiology: The Basic Science of Public Health
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The University of North Carolina at Chapel Hill
1349 оценок
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Course Introduction, History of Epidemiology and Epidemiology Research
This module introduces the history and field of epidemiology.
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Dr. Karin YeattsClinical Associate Professor
Department of Epidemiology, UNC Gillings School of Global Public Health
Dr. Lorraine AlexanderClinical Associate Professor, Director of Distance Learning (North Carolina Institute for Public Health)
Department of Epidemiology, UNC Gillings School of Global Public Health
[MUSIC]
I will now discuss several key people
noted for their role in history epidemiology.
Some people consider Hippocrates to be the first epidemiologist.
Hippocrates was a Greek physician.
He wrote a book called, On Airs, Waters, Places, where he described epidemics.
Hippocrates thought about environmental and behavioral issues that might
be associated with disease.
He focused on rational explanations for disease rather than
supernatural explanations, which were the norm during his time.
For example, malaria was even known about in ancient times.
Hippocrates described the malarial parasite
periodicity and the malarial paroxysm.
Which is a period of intense
chills, followed by a period of intense fever, followed by a period of
profuse sweating, followed by exacerbation or flare-up.
Hippocrates was in favor of swamp drainage to prevent miasma or bad night air.
As he observed it's link with yellow fever
and malaria in people living near these swamps.
Italian physician
Girolamo Fracastoro was another contributor to the field of epidemiology.
Fracastoro showed several ways that transmission of infections can occur.
By direct contact, by air, and via contaminated clothing.
In 1546, Fracastoro presented his writing on
contagion and contagious diseases, and proposed that
diseases were each caused by a rapidly multiplying seed.
He proposed that the seeds were transmitted
by direct contact, air, or contaminated garments.
After Fracastoro, John Graunt contributed to
epidemiology as one of the first demographers.
Demography is the statistical study of human populations.
Graunt calculated survivorship on a chart, and he presented population
and mortality statistics in London during the time of the plague.
The statistical and census methods that he developed
and used became the basis for modern demography.
John Graunt did an analysis of the vital statistics of people living in London.
He published his analyses in Natural and
Political Observations Made Upon the Bills of Mortality in 1662.
This publication was the first estimation
of the London population that was statistically-based.
Now we will talk about James Lind, who was a Scottish physician.
Lind was interested in the cause and treatment of scurvy.
Sailors in the 16 and 1700s
often suffered from scurvy.
Lind theorized that citrus fruits could cure scurvy.
Scurvy is now known to be caused by a vitamin C deficiency.
But back in the time of Lin, vitamins were unknown.
It is now known that vitamin C
is necessary to maintain healthy connective tissue.
In the 1700s, during the circumnavigation of the world by ship,
many sailors died, and many of those who died supposedly had scurvy.
Lind had the idea that something was lacking in the diet of the ill sailors.
Lind chose 12 men from a ship, all with scurvy, and sorted them into six pairs.
He gave each pair a different supplement to their diet.
All of the sailors received the same basic diet, but one group received
a quart of cider daily.
Group two received 25 drops of elixir of vitriol, or sulfuric acid.
Group three received six spoonfuls of vinegar.
Group four received half a pint of seawater.
Group five received two oranges and one lemon.
And the last group received a spicy paste.
Group five could no longer
be treated after six days when they no longer had any fruit.
However, one sailor in this group was already able to work.
While the other sailor had almost progressed to the
point that he too could soon return to his post.
Lind's work was a benefit to the field of preventative medicine, led to
improved nutrition and was a beginning
step leading to modern day clinical trials.
Percivall
Pott was an English surgeon in the 1700s. Pott is considered to be the
first person to show that an environmental carcinogen may cause cancer.
Pott noticed that London men working as chimney sweeps
had more scrotal skin sores than would be expected.
He noticed coal soot in the sores of the
men he examined and concluded that there was an association
between men routinely exposed to soot and scrotal cancer.
Pott's observations were the first time an environmental
factor was noted as a cancer causing agent.
Pott's work was the beginning of modern non-infectious disease epidemiology.
William Farr was a 19th century London epidemiologist
who's considered one of the founders of modern epidemiology.
Farr took statistical data and tested social hypotheses.
He also classified causes of death in a
way that accounted for broader factors that determine health.
Farr demonstrated a relationship between population density and mortality rates.
He also mapped deaths, monitored outbreaks, and developed
a new categorization system for causes of death.
The mortality data system that Farr developed was an antecedent
to the International Classification of Diseases System that is used today.
In 1849, there was a major outbreak of
cholera in London, in which 15,000 people died.
This image is an extract from Farr's report
on mortality from cholera in the 1849 outbreak.
It was published in the Annual Report
of the Registrar General for 1854.
Farr's report shows the relationship between water sources and cholera.
And he even further classified cholera
death by sub-districts of different elevations.
This image shows an excerpt from a table that Farr prepared.
Note the deaths of uncertain origin, particularly
starvation and scrofula, which is mycobacterial cervical lymphadenitis.
At this time, the causes of many health problems were still unknown.
Sir Edwin Chadwick studied sanitation issues in the United Kingdom.
Chadwick supported the idea that disease
was directly related to people's living conditions
and that there was a strong need for both public health and social reform.
Chadwick proposed improvements such as fresh, clean water,
water closets, which was a room with a flushing
toilet in each home, and a sewage carrying system.
Chadwick promoted use a special, water type
pipes for sewage to reduce drinking water contamination.
He thought that improvements in the health of
the poor would be good for the nation overall.
Chadwick published his ideas in The Sanitary
Condition of the Laboring Population in 1842.
London physician John Snow, is known as The Father of Modern Epidemiology.
Snow conducted the first outbreak investigation in London in 1854.
Snow showed an increase in patients with cholera
symptoms who lived or worked in one district.
Snow counted and mapped cases of cholera according to where people
lived and worked.
He noted that many people who lived on or near Broad Street had died.
All had been ill with cholera symptoms.
Snow is likely the first person who
geographically counted and mapped cases of a disease.
He compared Cholera in different parts of London and came to the conclusion
that people who used the Broad Street water pump had much higher rates
of illness when compared to people from other areas of London.
Snow's research showed that contaminated water had spread cholera.
Snow's work is often considered the beginning of
epidemiology, the study of health outcomes in populations.
This figure shows a map of cholera in London prepared by John Snow.
By the end of the outbreak, more than 600
people had died from cholera.
And all were exposed to water from the Broad Street pump.
This image shows the Broad Street pump.
Removing the pump handle was a control measure that further confirmed
John Snow's hypotheses, as a number of new cholera cases dropped.
John Snow's memory continues to live on today through the John Snow Society.
The John Snow Society
aims to promote the life and works of
Doctor John Snow, the pioneer of the epidemiologic method.
The John Snow Society encourages members to celebrate the memory of John Snow by
visiting the John Snow Pub, which is located on the site of the original pump.
This concludes our lecture on the history of epidemiology.
In the next lecture, you'll learn about the definitions
of epidemiology, and how epidemiology fits into public health.
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