Week 4: Week 4 - Epidemiology—Introduction Epidemiology—Introduction The study of epidemics is epidemiology. Its primary focus is on the distribution and causes of disease in populations. Epidemiology involves developing and testing ways to prevent and control disease by studying its origin, spread, and vulnerabilities. As a discipline, epidemiologic research addresses a variety of health-related questions of societal importance. Epidemiologic research methods are used by clinical investigators and scientists who conduct observational and experimental research on the prevention and treatment of disease. The Cholera epidemic, a case from the 19th century, was enabled by the global movement of people. Having appeared in India in 1817, it spread throughout Asia and the Middle East within a decade. It was reported in Moscow in 1830 and then spread to Warsaw, Hamburg, Berlin, and London in 1831 (Snow, 1855, 2002). When it crossed the Atlantic to reach North America, Cholera gained the notoriety of the first truly global disease. The modern day world is dominated by free trade and rapid transportation. An unprecedented rate of global interchange of food, consumer products, and organisms—including humans—is occurring. The threat of pandemics in the 21st century has heightened the importance of epidemiology at national and international levels. Although diseases such as Influenza A (H1N1), Severe Acute Respiratory Syndrome (SARS), Acquired Immunodeficiency Syndrome (AIDS), West Nile Virus, Salmonella, are commonly recognized as epidemics, as they cause large scale disruption of health in populations. The field of epidemiology also addresses epidemics of obesity (Ogden et al., 2007), diabetes (Zimmet, 2001), mental health (Insel & Fenton, 2005), and any other disease that may cause large scale disruption of health in populations. In general, there are ten stages to an outbreak investigation: 1. Investigation preparation 2. Outbreak confirmation 3. Case definition 4. Case identification 5. Descriptive epidemiology 6. Hypothesis generation 7. Hypothesis evaluation 8. Environmental studies 9. Control measures 10. Information dissemination Investigation preparation requires a health crisis manager to identify a team of professionals who will lead the outbreak investigation, review the scientific literature, and notify local, state, and national organizations of the potential outbreak. Outbreak confirmation requires actual laboratory confirmation of the disease, which may involve the collection of blood, urine, and stool samples from ill people and performing bacteriologic, virologic, or parasitic testing of those samples. Case definition is the process by which we establish a set of standard criteria to determine who is and is not infected with respect to a specific outbreak; that is, a protocol is developed to determine case patients. Case identification requires the health crisis manager and team of professionals to conduct a systematic and organize.

1. Week 4: Week 4 - Epidemiology—Introduction
Epidemiology—Introduction
The study of epidemics is epidemiology. Its primary focus is on
the distribution and causes of disease in populations.
Epidemiology involves developing and testing ways to prevent
and control disease by studying its origin, spread, and
vulnerabilities.
As a discipline, epidemiologic research addresses a variety of
health-related questions of societal importance. Epidemiologic
research methods are used by clinical investigators and
scientists who conduct observational and experimental research
on the prevention and treatment of disease.
The Cholera epidemic, a case from the 19th century, was
enabled by the global movement of people. Having appeared in
India in 1817, it spread throughout Asia and the Middle East
within a decade. It was reported in Moscow in 1830 and then
spread to Warsaw, Hamburg, Berlin, and London in 1831
(Snow, 1855, 2002). When it crossed the Atlantic to reach North
America, Cholera gained the notoriety of the first truly global
disease.
The modern day world is dominated by free trade and rapid
transportation. An unprecedented rate of global interchange of
food, consumer products, and organisms—including humans—is
occurring. The threat of pandemics in the 21st century has
heightened the importance of epidemiology at national and
international levels.
Although diseases such as Influenza A (H1N1), Severe Acute
Respiratory Syndrome (SARS), Acquired Immunodeficiency
Syndrome (AIDS), West Nile Virus, Salmonella, are commonly
recognized as epidemics, as they cause large scale disruption of

2. health in populations. The field of epidemiology also addresses
epidemics of obesity (Ogden et al., 2007), diabetes (Zimmet,
2001), mental health (Insel & Fenton, 2005), and any other
disease that may cause large scale disruption of health in
populations.
In general, there are ten stages to an outbreak investigation:
1. Investigation preparation
2. Outbreak confirmation
3. Case definition
4. Case identification
5. Descriptive epidemiology
6. Hypothesis generation
7. Hypothesis evaluation
8. Environmental studies
9. Control measures
10. Information dissemination
Investigation preparation requires a health crisis manager to
identify a team of professionals who will lead the outbreak
investigation, review the scientific literature, and notify local,
state, and national organizations of the potential outbreak.
Outbreak confirmation requires actual laboratory confirmation
of the disease, which may involve the collection of blood, urine,
and stool samples from ill people and performing bacteriologic,
virologic, or parasitic testing of those samples.
Case definition is the process by which we establish a set of
standard criteria to determine who is and is not infected with
respect to a specific outbreak; that is, a protocol is developed to
determine case patients.
Case identification requires the health crisis manager and team
of professionals to conduct a systematic and organized search
for case patients based on the standard criteria developed in the
case definition phase. Here, it is vital that the team identifies
both case patients (individuals already infected), as well as
individuals who may have been exposed.
Descriptive epidemiology requires the team to organize the
data—who was infected, when, where, etc.—identify

3. frequencies, and perform basic descriptive statistics that may
present patterns.
Hypothesis generation requires the team to generate hypotheses
as to why the outbreak occurred and compare the situation with
previous outbreaks or develop methods to collect additional
data.
Hypothesis evaluation requires more in depth statistical tests,
including an official epidemiologic study (cohort, case control,
etc.) and comparing potential risk factors among those infected
(cases) and those not infected (controls).
Additional studies may call for environmental
diagnoses requiring collection and analysis of food, water, and
other environmental samples. Once all data has been collected
and examined, the team will work to implement control and
prevention measures by coordinating with community partner
organizations.
Finally, the health crisis management team will communicate
their findings via an outbreak investigation report that is
tailored for the scientific community as well as lay persons. The
primary goal of the information dissemination stage is to
educate the community about the outbreak and instill the
knowledge needed to prevent further outbreaks.
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Week 4: Week 4 - The Threat of SARS Case Study
The Threat of SARS Case Study
You are the director of communicable diseases in a city health

4. department, responsible for a large urban community. It is early
spring in 2003. For the past two years, your department has
been working to control the spread of the West Nile Virus and
you are pleased with the progress so far. This morning you read
about a suspected outbreak of a new disease called SARS which
is suspected to have killed dozens of people in Hong Kong.
While West Nile Virus is carried by birds, especially crows,
SARS is transmitted among people.
When you get to the office and check your email you learn that
the World Health Organization has placed a number of East
Asian cities off limits for all but essential travel. You also learn
that Canada has reported deaths they believe are due to SARS.
You are now confronted with addressing a new and virulent
contagious disease. What should you do?
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Week 4: Week 4 - Health Crisis Management
Health Crisis Management
A public health crisis is described as an emerging situation that
affects a large population, often spanning a wide geographic
area, usually in a very short period of time. The severity of the
crisis is measured by the number of people affected in relation
to the geographic extent or by the intensity of the causative
agent, such as a disease, toxin, or poor policy decisions.
Health crisis can occur in many forms and at multiple scales.
Health care organizations themselves have internal health
crises, which are often in the form of spreading infection. This
is so common that hospitals employ infectious disease

5. specialists and epidemiologists to routinely locate and contain
disease outbreaks. For instance, in the very first chapter of his
book, On Washing Hands, Dr. Atul Gawande (2007) describes
how inexplicably common it is for hospital personnel to not
wash their hands and cause the spread of infections. In the
United States, it has been estimated that approximately two
million health care associated-infections (HAI) occur each year,
resulting in 60,000 to 90,000 deaths. The cost is estimated to be
at least $17 to $29 billion (Jarvis, 2007).
At a global scale, health crises may be even more difficult to
manage owing to several complexities. This is when the
infection rates from super-resistant bacteria have increased
throughout the world, and humans travel in unprecedented
numbers and at a very fast pace. For example, transmitting
primarily through the hands of health care workers, the SARS
virus—having first appeared in the Guangdong Province of
China in late 2002—spread within a few months to over twenty
five countries, infecting over 8,000 people and causing 774
deaths, as reported by the Centers for Disease Control and
Prevention (CDC). There are several opportunities for such
incidents to quickly escalate to crises levels.
Public health emergencies may come from several other sectors
as well. In its website, the office of the Assistant Secretary for
Preparedness and Response (ASPR) of the US Department of
Health and Human Services (HHS) lists four major kinds of
emergencies:
· Oil or chemical spills
· Biohazard or infectious disease
· Food safety issues
· Terrorism or criminal activity
It is very likely that all of these emergencies will require health
care emergency managers to plan and prepare for contingencies.
The outcome of how a crisis is managed is largely dependent on
the knowhow, experience, and the personality of the manager.
No matter how much planning is done and protocol followed,
emergency managers need to have strong leadership qualities in

6. order to handle crises. Having a working knowledge of the
health care field is also critical in this context. During an
emergent health crisis, the manager needs to coordinate between
various groups, communicate decisively and clearly in order to
avoid panic, and optimize the distribution of resources.
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