Epidemiology

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Epidemiology

• Biology 101L
• Exercise 13

Image geo.arc.nasa.gov/sge/ health/gmhh/mexico.ht
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• Activity
• You will need to wear gloves for all class
  activities today.
• Pick a random identification card up from the
  front desk (record this ID code in Table 3).
• Switch cards with your partners (record your new
  code in Table 3).
• Pass your card to another group and take theirs
  (record your final code in Table 3).
• Thats it for now!

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What is Epidemiology?

• Study of disease in populations
• Study of patterns, causes and control of disease
  in populations
• The branch of medicine that deals with the study
  of the causes, distribution, and control of
  disease in populations.
• The study of the spread of diseases within and
  between populations.

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• Hawaiis Department of Health (DOH)

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DOH Mission

• To provide leadership to monitor, promote,
  protect and enhance the health and environmental
  well-being of people who live in Hawaii

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Public Health and
Epidemiology

• Public Health
• The science and practice of protecting and
  improving the health of a community
• Epidemiology
• The branch of medicine that deals with the study
  of the causes, distribution, and control of
  disease in populations
• Epidemic
• An outbreak of a contagious disease that spreads
  rapidly and widely

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Characteristics of an epidemic

• Highly contagious
• High mortality
• Spreads rapidly
• Unknown or poor prevention mechanism

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To Consider

• Rapid fatality tends to limit the spread of a
  disease
• Mutations can quickly overcome existing immune
  barriers
• Not all countries are willing to admit there is a
  serious problems and this can delay containment
• Political recognition may hamper information
  gathering (e.g., Taiwan and China-SARS)

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Examples
Smallpox Hemorrhagic Fevers (e.g., Ebola,
Dengue) Flu Cholera HIV/AIDS SARS Bird
Flu Tuberculosis Leprosy Bubonic plague Measles
and more
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Problems
AIDS
Acquired Immunodeficiency Syndrome HIV (virus)
attacks T-cells Weakens or eliminates immune
system Susceptible to many fatal diseases
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AIDS

• In 1983, a retrovirus, now called human
  immunodeficiency virus (HIV), had been identified
  as the causative agent of AIDS.

HIV budding
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AIDS
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AIDS
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5 people die of AIDS every minute 42 million
infected 2002 - 5 million infected 37 million
adults living with AIDS 2.5 million under 15
living with AIDS 2003 - 5 million newly
infected 2003 - 3 million AIDS deaths
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HIV/AIDS in Hawaii
Living w/AIDS Cumulative cases
2833
2770
2720
2585
3,000
2,500
2461
1318
2,000
1271
1247
1070
1,500
987
1,000
500
2000 2001 2002 2003 2004
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• With the AIDS mortality close to 100, HIV is the
  most lethal pathogen ever encountered.
• Molecular studies reveal that the virus probably
  evolved from another HIV-like virus in
  chimpanzees in central Africa and appeared in
  humans sometimes between 1915 and 1940.
• These first rare cases of infection and AIDS went
  unrecognized.

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• HIV Testing
• The HIV antibody test has be used to screen all
  blood supplies in the U.S. since 1985.
• May take weeks or months before anti-HIV
  antibodies become detectable.
• Drug treatment available
• Best prevention is education and protected sex

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SARS

• Name(s) of the disease Severe Acute Respiratory
  Syndrome (SARS)
• Causative agent (e.g., virus, bacterium)
  SARS-associated coronavirus (SARS-CoV).
• Method of transmission (including whether
  caregivers are at high risk) person to person
  contact via respiratory droplets deposited on the
  mucous membranes of the persons nearby, or via
  touching surface with virus then touching mucous
  membranes, or airborne spread

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• Symptoms In general, SARS begins with a high
  fever (temperature greater than 100.4F
  gt38.0C). Other symptoms may include headache,
  an overall feeling of discomfort, and body aches.
  Some people also have mild respiratory symptoms
  at the outset. About 10 percent to 20 percent of
  patients have diarrhea. After 2 to 7 days, SARS
  patients may develop a dry cough. Most patients
  develop pneumonia.
• Treatment CDC recommends that patients with
  SARS receive the same treatment that would be
  used for a patient with any serious
  community-acquired atypical pneumonia. SARS-CoV
  is being tested against various antiviral drugs
  to see if an effective treatment can be found.
• Mortality statistics During November 2002
  through July 2003, a total of 8,098 people
  worldwide became sick. Of these, 774 died.

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Current threats (i.e., outbreaksrecent changes
in abundance, reservoirs) In April 2004, the
Chinese Ministry of Health reported several new
cases of possible SARS in Beijing and in Anhui
Province, which is located in east-central China.
As of April 26, the Ministry of Health had
reported eight possible SARS cases six in Bejing
and two in Anhui Province. One of the patients in
Anhui Province died. Nearly 1000 contacts of
these patients with possible SARS are under
medical observation, including 640 in Beijing and
353 in Anhui
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Class Exercise 1
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Class Exercise 1 You will study portals of
entry, methods of transmission, and control of
infectious diseases. In addition, using the
internet you will examine the CDCs method of
reporting, tracking and controlling epidemics.  
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Class Exercise 1

• Work as a team (2 students /group)
• Select 1 infectious diseases from the Table 1
  labeled Nationally Notifiable Infectious
  Diseases.
• Conduct a web search and fill out Epidemiology
  Worksheet.
• Report findings to class

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Disease Characterization

• Name(s) of the disease
• Causative agent (e.g., virus, bacterium, protist,
  fungus)
• Mode of transmission (including whether
  caregivers are at high risk)
• Degree of infectiousness
• Symptoms
• Treatment
• Mortality statistics

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Historical Epidemiology

• Preventative measures
• (e.g., immunization programs, public health
  practices)
• Major historical events
• (e.g., date, location, total deaths, speed of
  spread)
• Notification network
• (e.g., who is keeping track)
• Current threats
• (e.g., outbreaksrecent changes in abundance,
  reservoirs)

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Local Impact

• Are caregivers at an especially high risk?
• Is the local population at particularly high risk
  (e.g., lots of elderly, children)?
• Is there a history of this disease in Hawaii?

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Mystery Exercise 2
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Track the spread of a contaminant
One of your classmates is the carrier of a
harmless pathogen. Your instructor knows the
identity of the carrier. It is up to you to
determine who it is!
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Track the spread of a contaminant

• Use a UV florescent black light to determine if
  you have contracted the infectious agent.
• If your gloved hand fluoresces under the light,
  you or one of your contacts is a carrier of the
  disease.

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Questions
Q1. How many students have contracted the
infectious agent? Q2. What percentage of the
student groups does that cover? Q3. Who are the
suspected carriers (they would be common among
the groups whose hand fluoresced)? Codes Q4. Can
you determine the primary source(s), the
spreading point(s), of the infection?
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What are some things you can do to reduce the
spread of disease?
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Hand washing time!
Time to answer the question How clean are your
hands?
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Hand washing time!

• Place a few drops of a fluorescent dye on your
  palm.
• Rub your hands together front and back.
• Scratch your palm with your nails.
• Look at them under a UV light.
• Go wash and look at them again.
• How well did you do?

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When Conservation and Health Concerns Collide
Critical Thinking 1

• What happens when disease eradication takes a
  high toll on biodiversity?

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Critical Thinking 2a
Critical Thinking 2a

• Some positive conservation successes can have
  negative human health impacts

• Ex Rebounding marine mammal populations
• Increased incidence of human intestinal worms
• Ex Regenerating forest
• Increased incidence of Leishmaniasis in Sudan
• Increased incidence of Lyme disease in the USA

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Critical Thinking 2b

• Some types of environmental degradation can have
  positive human health impacts

• Ex Conversion of forest to cattle pasture in
  Honduras
• Reduced malaria vector population size
• Ex Clear-cut logging
• Reduced exposure to wildlife diseases

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Parallel Drivers?
Critical Thinking 3

• Does biodiversity loss per se drive changes in
  human health?

• Or -could changes in human health and
  biodiversity both be driven by environmental
  degradation?

• Would that change our interpretation of observed
  patterns?

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Critical Thinking 4 Parks for Pathogens?

• Preserving pathogens and parasites might be a key
  component of successful conservation strategies

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HOMEWORK
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Homework Assignment

• Chose 1 of the diseases listed on Table 3.
• Fill-out the same epidemiology worksheet you you
  used in class.
• Please type it.
• Visit the suggested link and use the suggested
  resources (as well as other resources) to answer
  your worksheet.
• You must include any additional resources used
  for your homework assignment.
• Turn in next class.