EpidemiologyEpidemiology

Biology 101L

Exercise 13Image: 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!

• 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.

What is Epidemiology?

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

• 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

Epidemiology

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:Examples:

SmallpoxHemorrhagic Fevers (e.g., Ebola, Dengue)FluCholeraHIV/AIDSSARSBird FluTuberculosisLeprosyBubonic plagueMeasles and more…

SmallpoxHemorrhagic Fevers (e.g., Ebola, Dengue)FluCholeraHIV/AIDSSARSBird FluTuberculosisLeprosyBubonic plagueMeasles and more…

AIDS

Acquired Immunodeficiency Syndrome

HIV (virus) attacks T-cells

Weakens or eliminates immune system

Susceptible to many fatal diseases

Problems

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

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

HIV/AIDS in Hawaii

2000 2001 2002 2003 2004

2461

987

500

1,000

1,500

2,000

2,500

3,000 2585

1070

2720

1247

2833

1318

2770

1271

Living w/AIDS

Cumulative cases

• 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

• 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

SARS

• 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

• 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

Disease Characterization:

• 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)

Historical Epidemiology:

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.

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?

Questions

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?

When Conservation and Health Concerns Collide

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

Critical Thinking 1Critical Thinking 1

Critical Thinking 2aCritical Thinking 2a Some positive conservation successes can Some positive conservation successes can

have negative human health impactshave negative human health impacts

Ex: Rebounding marine mammal populationsEx: Rebounding marine mammal populations Increased incidence of human intestinal Increased incidence of human intestinal

wormsworms Ex: Regenerating forestEx: Regenerating forest

Increased incidence of incidence of Leishmaniasis in Sudan

Increased incidence of incidence of Lyme disease in the USA

Critical Thinking 2aCritical Thinking 2a

Critical Thinking 2bCritical Thinking 2b Some types of environmental degradation Some types of environmental degradation

can have positive human health impactscan have positive human health impacts

Ex: Conversion of forest to cattle pasture in Ex: Conversion of forest to cattle pasture in HondurasHonduras Reduced malaria vector population size

Ex: Clear-cut loggingEx: Clear-cut logging Reduced exposure to wildlife diseases

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

Human Health

Biodiversity Loss

Environmental Degradation

Biodiversity Loss

Human Health

Environmental Degradation

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

Would that change our interpretation of observed patterns?

Critical Thinking 3Critical Thinking 3Parallel Drivers?

Critical Thinking 4: Parks for Pathogens?

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

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.