ANTC67: Midterm Notes
Chapter 1: What is Epidemiology?
¾ ]u]}o}PÇ}]P]v(}u,]}[}À]}vu}ZvîìììÇP}ZvÀ]}vuvo(}]v(oµvZ}µrence of
¾ Epidemiology in its modern form is a relatively new discipline and uses quantitative methods to study diseases in human populations to
inform prevention and control efforts.
Box 1.1 Early Epidemiological Observation
¾ John Snow located the home of each person who died from cholera in London during 1848-49 and 1853-54, and noted an apparent
association between the source of drinking water and the deaths.
¾ He compared cholera deaths in districts with different water supplies and showed that both the number of deaths and the rate of deaths
were higher among people supplied water by the Southwark Company.
¾ Snow constructed a theory about the communication of infectious diseases and suggested that cholera was spread by contaminated
water. He was able to encourage improvements in the water supply long before the discovery of the organism responsible for cholera.
¾ Outbreaks of cholera are still frequent among poor populations.
Definition, Scope, and Uses of Epidemiology
¾ ]u]}o}PÇ(]vÇ>]^ZµÇ}(Z]]µ]}ns and determinants of health-related states or events in specified
populations, and the application of this study to the prevention and control of health problems.
¾ A focus of an epidemiological study is the population defined in geographical or other terms.
¾ A common population used in epidemiology is one selected from a specific area or country at a specific time. This forms the base for
defining subgroups with respects to sex, age or ethnicity.
¾ Epidemiological analyses must take into account that the structures of populations vary between geographical areas and time periods.
Epidemiology and Public Health
¾ Public health, broadly speaking, refers to collective actions to improve population health.
¾ Although some diseases are caused solely by genetic factors, most result from an interaction between genetic and environmental factors.
Diabetes for example, has both genetic and environmental components.
¾ We define environment broadly to include any biological, chemical, physical, psychological, economic or cultural factors that can affect
¾ Epidemiology is also concerned with the course and outcome (natural history) of diseases in individual and groups.
¾ Knowledge of the disease burden in populations is essential for health authorities, who seek to use limited resources to the best possible
effect by identifying priority health programmes for prevention and care.
¾ Applying epidemiological principles and methods to problems encountered in the practice of medicine has led to the development of
¾ Similarly, epidemiology has expanded into other fields such as pharmacoepidemiology, molecular epidemiology, and genetic
Box 1.3 Molecular and Genetic Epidemiology
¾ Molecular epidemiology measures exposure to specific substances and early biological response, by:
o Evaluating host characteristics mediating response to external agents, and
o Using biochemical markers of a specific effect to refine disease categories.
¾ Genetic epidemiology deals with the etiology, distribution, and control of disease in groups of relatives, and with inherited causes of
disease in populations. Genetic epidemiological research in family or population studies aims to establish:
o A genetic component to the disorder,
o The relative size of that genetic effect in relation to other sources of variation in disease risk, and
o The responsible gene(s)
¾ Public health genetics include:
o Population screening programs,
o Organizing and evaluating services for patients with genetic disorders, and
o The impact of genetics on medical practice.