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Lab Exercise #15 Infections, Infectious Disease, and Epidemiology
Objectives
1. Describe the portals of entry and relate these to the routes of
transmission for common infections
2. Describe the important components in controlling
an epidemic.
3. Analyze the source, transmission, and potential
impact of an epidemic when provided pertinent
data.
4. Use appropriate types of graphs to display the data
and interpret epidemic trends.
5. Critically evaluate and suggest methods to prevent
or control an epidemic.
6. Describe the unique social conditions that surround the STD epidemic in
the U.S.
7. Access and use the MMWR to look up epidemiologic information.
Epidemiology is the study of the spread of disease through a population. An
increase in the prevalence of a disease over a given time, within a specific
area or affecting a particular population, it is considered an epidemic. Data is
collected on the agent, number of cases, the location and history of the
disease, ages involved, contributing factors and other pertinent information.
Analysis of these details provides data to determine whether a vaccine,
chemotherapeutic agent, quarantine, vector control, behavioral changes, or
other precautions may control the disease spread. Depending upon the
morbidity or mortality of the disease, strict measures may have to be
implemented to control it. One example of these measures are the list of
required reportable diseases. The table on the next page lists the nationally
notifiable diseases which must be reported to the public health department
in the United States.
In this lab exercise 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.
There will also be a simulated epidemic in the classroom which you will track
and analyze. In part 1 complete the charts below using the text and other
outside sources. In part 2 following the lab simulation, create a graph of the
data from the simulated epidemic, make a prediction as to the spread
without further intervention, and describe methods of intervention that
would be effective.
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NAME________________________
Lab Exercise #15 Infections, Infectious Disease, and Epidemiology
Using your text fill in the tables below concerning information about portals
of entry and modes of transmission of infectious diseases.
1. Portal of Entry
Portal of Entry
Skin
Mucous
Membranes
Placenta
Gastrointestinal
Route
Parenteral
Route
Example of a disease using this
portal of entry
Methods to prevent the spread of a
disease using this portal of entry.
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2. Modes of Transmission
Mode of Transmission
Direct contract
Indirect contact
Airborne
Food and waterborne
Vector
How does this type of transmission
occur, under what circumstances?
Examples of diseases spread via
this mode of transmission.
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3. Examining an Epidemic
Download one of the following recent Kern County epidemics according to
your table number:
Table 1
Table 2
Table 3
Table 4
E.coli in Milk
West Nile Virus
WEE
Meningococcus
Table 6
Table 7
Table 5
Table 8
Hepatitis A
E.coli source
HIV
Rabies
unknown
Examine the information about this epidemic reported news release. Get further national
information from the MMWR (Morbidity and Mortality Weekly Report) from CDC, access this
at http://www.cdc.gov/mmwr/ Using your textbook, information referred to in the report
and CDC information, provide a brief paragraph describing the disease; include the etiologic
agent, portal of entry, mode of transmission, symptoms and type of treatment. What factors
may have contributed to the spread of this epidemic? What factors may be important in
controlling the spread of this disease?
Name of the etiologic agent causing the epidemic:
Classification:
Brief description of this agent:
Portal of Entry:
Mode of Transmission:
Symptoms:
Treatment:
Means of Epidemiologic Control:
Is this a reportable disease?
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4. Following a Simulated Epidemic
The disease that you are tracking is the most prevalent STD in the United
States caused by Chlamydia trachomatis, an obligate intracellular bacteria.
Approximately 3 - 4 million Americans suffer from infections every year
costing nearly 1 billion dollars. No one appears to develop immunity after
contracting the disease. Often infected women show no obvious symptoms,
while approximately 75% of men are symptomatic. In men the disease
produces urethritis resulting in painful urination and a discharge from the
urethra, sometimes being confused with gonorrhea. Two serious
complications occur as a result of this disease:
1) Chlamydia may spread to the fallopian tubes resulting in PID (pelvic
inflammatory disease). Approximately 500,000 cases of PID due to
Chlamydia occur every year.
2) Infants, born to infected mothers, are at high risk for developing eye
infections leading to blindness. Other than trauma related injury,
Trachoma is the leading cause of blindness in the world.
Chlamydia can be treated with tetracycline and erythromycin. There are no
vaccines available.
MATERIALS:
1 pipette
1 empty tube
1 full tube
developing solution
latex gloves
test tube rack
PROCEDURE:
1. Write the number of your tube on the data chart, label the full tube “round #1” and
the empty tube “round #2”. This tube represents your body fluids. Only one person is
infected. No one will know who the infected class member is.
2. We will proceed by sharing body fluids (about 1ml), one at a time with someone else
in the lab. Follow the instructor's directions carefully. You must exchange body
fluids: pipette 1 ml of your fluid into the another person’s tube, when directed, and
allow them to pipette 1 ml into your tube.
3. After the first round, pipette pour approximately half the volume of your round #1
tube into the tube marked #2
4. Proceed with a second round of sharing body fluids again pipetting 1 ml into another
person’s tube.
5. When the class has completed 2 rounds place the tubes in the rack and remove the
caps. The instructor will bring around developing fluid to identify those that have the
disease. Any indication of a color change is considered positive.
6. Together we will record the class data on the chart. Try to analyze the spread of
infection and answer the questions on the next sheet.
7. Graph the information. Remember to title the graph and label all the axes properly.
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CLASS DATA CHART
Person Round
#1 + / -
Contact
+ or -
Person Round
#2 + / -
1.
1.
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Contact
+ or -
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The number of your test tube:
How many carriers resulted after round #1?
(Make a hypothesis concerning any abnormal or unexplained results)
How many carriers after round #2?
Draw a graph and attach it to this lab of disease over time. Predict where the third
round results may have been.
Name of the etiologic agent causing the epidemic:
Classification:
Briefly describe this agent:
Portal of Entry:
Who was patient Zero? Describe your rationale or draw a flow chart on the
back of this page.
Mode of Transmission:
Symptoms:
Treatment:
Means of Epidemiologic Control: What specific aspects of the disease make it
difficult to control? (Consider cost, practicality, and social constraints.)
Is this a reportable disease?
1801 Panorama Dr. - Bakersfield, CA 93305 - (661)395-4011
Last Updated 8/27/2007
©Janet Fulks