Epidemiology by YZvGEtUS

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									Epidemiology




        Biology 101L
        Exercise 13
Image: geo.arc.nasa.gov/sge/ health/gmhh/mexico.html
Activity:
1. You will need to wear gloves for all class
   activities today.
2. Pick a random identification card up from
   the front desk (record this ID code in Table
   3).
3. Switch cards with your partners (record
   your new code in Table 3).
4. Pass your card to another group and take
   theirs (record your final code in Table 3).
5. That’s it for now!
     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.
  Hawai`i’s
Department of
Health (DOH)
        DOH Mission:

  To provide leadership to monitor,
  promote, protect and enhance the
health and environmental well-being of
      people who live in Hawai`i
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
Characteristics of an epidemic


            •   Highly contagious
            •   High mortality
            •   Spreads rapidly
            •   Unknown or poor
                prevention
                mechanism
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)
Examples:
Smallpox
Hemorrhagic Fevers (e.g., Ebola, Dengue)
Flu
Cholera
HIV/AIDS
SARS
Bird Flu
Tuberculosis
Leprosy
Bubonic plague
Measles and more…
         Problems
AIDS
 Acquired Immunodeficiency
   Syndrome
 HIV (virus) attacks T-cells
 Weakens or eliminates immune
  system
 Susceptible to many fatal diseases
                 AIDS
• In 1983, a retrovirus, now called human
  immunodeficiency virus (HIV), had been
  identified as the causative agent of AIDS.




   HIV budding
AIDS
AIDS
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
 Living w/AIDS
 Cumulative cases
                       HIV/AIDS in Hawaii
                                                           2833          2770
                                             2720
                               2585
3,000

2,500               2461

2,000                                                1318
                                       1247                        1271
                           1070
1,500
                 987
1,000

 500


            2000        2001          2002          2003          2004
• 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.
• 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
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
•   Symptoms: In general, SARS begins with a high
    fever (temperature greater than 100.4°F [>38.0°C]).
    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.
Current threats (i.e., outbreaks—recent
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
Class Exercise 1
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 CDC’s method of reporting,
tracking and controlling epidemics.
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
 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
  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., outbreaks—recent changes in
  abundance, reservoirs)
 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
  Hawai`i?
Mystery Exercise 2
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!
Track the spread of a contaminant

1. Use a UV florescent black light to determine
   if you have contracted the ―infectious agent.‖

2. If your gloved hand fluoresces under the
   light, you or one of your contacts is a carrier
   of the disease.
           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?
What are some things you
can do to reduce the
spread of disease?
   Hand washing time!
Time to answer the question:
―How clean are your hands?‖
     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?
         Critical Thinking 1
When Conservation and Health Concerns
               Collide
• What happens
  when disease
  eradication
  takes a high toll
  on biodiversity?
              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
               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
         Critical Thinking 3
             Parallel Drivers?
• 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?
Human        Biodiversity   Human               Biodiversity
Health          Loss        Health                 Loss


    Environmental                    Environmental
     Degradation                      Degradation
         Critical Thinking 4:
        Parks for Pathogens?
   Preserving pathogens and parasites might be
    a key component of successful conservation
    strategies
HOMEWORK
       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.

								
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