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Lesson
1
What Are Communicable Diseases?
When was the last time you had a cold?
How did you treat it?
Lesson
1
Lesson Objectives
In this lesson, you will learn to:
• Identify the types of pathogens that cause
communicable diseases
• Describe the ways in which communicable
diseases are spread
• Develop strategies to help prevent communicable
diseases
Lesson
1
What Are Communicable Diseases?
Microorganisms and Communicable Diseases
• Although most microorganisms—living
things too small to be seen without a
microscope—are harmless, a few can
cause communicable diseases.
• Knowing how communicable
diseases spread can help you
choose behaviors to reduce
your risk of getting them.
Lesson
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Causes of Communicable Diseases
Pathogens
• Common pathogens include certain viruses, bacteria, fungi,
protozoans, and rickettsias.
• Pathogens cause diseases.
• If the body is not able to fight off an infection, a disease
develops.
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Causes of Communicable Diseases
Diseases by Type of Pathogen
Lesson
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Causes of Communicable Diseases
Viruses
• Viruses by themselves are inactive—they need living cells to
reproduce.
• After a virus penetrates a cell (called the host cell), the virus
takes control of the cell to manufacture more viruses.
• The new viruses burst from the cell, usually killing it, and
take over other cells.
• Viruses usually run their course and eventually are killed by
the immune system.
• Antibiotics do not work against viruses.
Lesson
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Causes of Communicable Diseases
Bacteria
• Most bacteria are harmless, and many types are essential
for life.
• When bacteria enter the body, they multiply through cell
division.
• Some bacterial pathogens, such as the ones that cause
tetanus, produce a toxin.
• Bacteria are usually destroyed by the immune system.
• Most bacterial diseases can be treated with antibiotics.
Lesson
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Causes of Communicable Diseases
Other Types of Pathogens
• Fungi are plantlike organisms. Some types can cause
diseases of the skin and diseases of the mucous membranes.
• Protozoans are single-celled organisms that are larger and
more complex than bacteria.
• Rickettsias are pathogens that resemble bacteria. Often
these organisms enter humans through the bites of insects.
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How Communicable Diseases Are Transmitted
Transmission of Communicable Diseases
• Transmission can occur through direct and indirect contact
and through breathing contaminated air.
• If you know how they are spread, you can take precautions
and avoid infection.
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How Communicable Diseases Are Transmitted
Direct Contact
• Direct contact includes touching, biting, kissing, and sexual
contact.
• Sneezing and coughing can spray infectious droplets of saliva
or mucus into a nearby person’s eyes, nose, or mouth.
• A pregnant female may also transmit an infection to her
unborn child through the placenta.
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How Communicable Diseases Are Transmitted
Indirect Contact
• Contaminated objects: Inanimate objects can become
contaminated with infectious discharges or secretions.
• Vectors: Common vectors include flies, mosquitoes, and
ticks. Lyme disease and malaria are spread by vectors.
• Water and food: Careless handling and storage of food
and water supplies that become contaminated with human
or animal feces are major sources of contamination and
illness.
Lesson
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How Communicable Diseases Are Transmitted
Airborne Transmission
• Airborne transmission is different from direct contact
because the pathogens don’t settle quickly on surfaces.
• You don’t have to be close to an infected person to inhale the
pathogens.
• Diseases that are transmitted this way include chicken pox,
tuberculosis, and influenza.
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Strategies for Preventing Communicable Disease
Washing Hands
• Handwashing is the single most effective strategy for
preventing the spread of disease.
• Wash your hands before you prepare food, before you eat,
and after you use the bathroom.
• Make it a habit to wash your hands after handling animals
(especially reptiles) or animal wastes.
• When someone in your home is ill, keep hands clean to
prevent the spread of pathogens.
Lesson
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Strategies for Preventing Communicable Disease
Handling Food Properly
• Foodborne illness occurs in places where food is handled
improperly.
• Always wash your hands before you handle food.
• Use paper towels, not dishcloths or sponges, to keep
surfaces and equipment clean.
• Separate raw meat from other foods. Cook food to its
proper temperature.
• Chill cold and leftover foods quickly to the proper
temperature.
Lesson
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Strategies for Preventing Communicable Disease
Other Prevention Strategies
Avoid sharing eating utensils, makeup, combs and
brushes, and other personal items.
Avoid unnecessary contact with people who are ill.
Cover your mouth when you cough or sneeze.
Be sure you are vaccinated against particular
diseases as recommended by your physician.
Practice abstinence from sexual activity.
Learn to manage stress.
Lesson
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Quick Review
Q. Which of the following is NOT a type of common
pathogen and the disease it causes?
1. Viruses: influenza, bacteria, tuberculosis
2. Cortex: pathenogens, bacteria, cirrhosis
3. Fungi: athlete’s foot, protozoans, malaria
4. Rickettsias: typhus, bacteria, tuberculosis
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Quick Review - Answer
A. 2. Cortex: pathenogens, bacteria, cirrhosis
Types of common pathogens and the diseases they cause
do NOT include cortex—pathenogens, bacteria, cirrhosis.
Click Next to attempt another question.
Lesson
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Quick Review
Q. Pathogens can spread through direct and indirect
contact and through breathing contaminated air.
Which of the following is NOT a habit you can adopt to
limit their spread?
1. Washing your hands
2. Inspecting your throat for redness and mucus
3. Covering your mouth when you cough or sneeze
4. Being sure you are vaccinated against particular
diseases as recommended by your physician
Lesson
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Quick Review - Answer
A. 2. Inspecting your throat for redness and mucus
Pathogens can spread through direct and indirect contact
and through breathing contaminated air. Habits that can
be adopted to limit their spread does NOT include
inspecting your throat for redness and mucus.
Click Next to attempt another question.
Lesson
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Quick Review
Q. Your risk of getting a communicable disease is less if
you
1. eat a balanced diet.
2. participate in regular physical activity.
3. avoid the use of tobacco, alcohol, and
other drugs.
4. All of the above
Lesson
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Quick Review - Answer
A. 4. All of the above
Your risk of getting a communicable disease is less if you
eat a balanced diet; participate in regular physical activity;
avoid the use of tobacco, alcohol, and other drugs.
Click Next to attempt another question.
Lesson
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Quick Review
Choose the appropriate option.
Q. The fungus that causes athlete’s
foot lives in warm, moist places.
It is a pathogen that can be
easily caught at the gym or in
communal showers.
True
False
Lesson
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Quick Review - Answer
A. True. The fungus that causes athlete’s foot lives in warm,
moist places. It is a pathogen that can be easily caught
at the gym or in communal showers.
Lesson
1
End of Lesson 1
Click Home to view the Main menu.
Lesson
1
Quick Review - Answer
A. Correct! Types of common pathogens and the diseases
they cause do NOT include: cortex—pathenogens,
bacteria, cirrhosis.
Lesson
1
Quick Review - Answer
You have answered the question incorrectly. Go back to try
again, or click Next to view the correct answer.
Lesson
1
Quick Review - Answer
A. Correct! Pathogens can spread through direct and indirect
contact and through breathing contaminated air. Habits
that can be adopted to limit their spread does NOT
include: inspecting your throat for redness and
mucus.
Lesson
1
Quick Review - Answer
You have answered the question incorrectly. Go back to try
again, or click Next to view the correct answer.
Lesson
1
Quick Review - Answer
A. Correct! Your risk of getting a communicable disease is
less if you do all of the following: eat a balanced diet;
participate in regular physical activity; avoid the use of
tobacco, alcohol, and other drugs.
Lesson
1
Quick Review - Answer
You have answered the question incorrectly. Go back to try
again, or click Next to view the correct answer.
Lesson
1
Quick Review - Answer
A. Correct! The fungus that causes athlete’s foot lives in
warm, moist places. It is a pathogen that can be easily
caught at the gym or in communal showers.
Lesson
1
Quick Review - Answer
You have answered the question incorrectly. Go back to try
again, or click Next to view the correct answer.
Lesson
1
What Are Communicable Diseases?
Microorganisms and Communicable Diseases
• Although most microorganisms—living
things too small to be seen without a
microscope—are harmless, a few can
cause communicable diseases.
• Knowing how communicable
A communicable
diseases spread can help you
disease is a disease
choose behaviors to reduce
that is spread from
your risk of getting them.
one living thing to
another or through
the environment.
Lesson
1
Causes of Communicable Diseases
Pathogens
• Common pathogens include certain viruses, bacteria, fungi,
protozoans, and rickettsias.
pathogen
• Pathogens causeAdiseases.
is an organism
causes
• If the body that
is not
able to fight off an infection, a disease
develops. disease.
Lesson
1
Causes of Communicable Diseases
Pathogens
• Common pathogens include certain viruses, bacteria, fungi,
protozoans, and rickettsias.
• Pathogens cause diseases.
• If the body is not able to fight off an infection, a disease
develops.
An infection is a
condition that occurs
when pathogens
enter the body,
multiply, and
damage body cells.
Lesson
1
Causes of Communicable Diseases
Pathogens
• Common pathogens include certain viruses, bacteria, fungi,
protozoans, and rickettsias.
A virus is a
• Pathogens cause diseases.
piece of genetic
material
that
• If the body is not able
to fight
off invade
an infection, a disease
living cells to
develops.
reproduce.
Lesson
1
Causes of Communicable Diseases
Pathogens
• Common pathogens include certain viruses, bacteria, fungi,
protozoans, and rickettsias.
Bacteria are
single-celled
microorganisms.
• If the body is not able to fight off an infection, a disease
develops.
• Pathogens cause diseases.
Lesson
1
Causes of Communicable Diseases
Bacteria
• Most bacteria are harmless, and many types are essential
for life.
• When bacteria enter the body, they multiply through cell
division.
• Some bacterial pathogens, such as the ones that cause
tetanus, produce a toxin.
Toxin is a
• Bacteria are usually destroyed
by thethat
immune
substance
kills system.
cells or interferes
• Most bacterial diseases can
be their
treated
with antibiotics.
with
functions.
Lesson
1
How Communicable Diseases Are Transmitted
Indirect Contact
• Contaminated objects: Inanimate objects can become
contaminated with infectious discharges or secretions.
• Vectors: Common vectors include flies, mosquitoes, and
ticks. Lyme disease and malaria are spread by vectors.
Vector is an
organism,
• Water and
food: usually
Carelessanhandling and storage of food
arthropod,
as a
and water
supplies such
that become
contaminated with human
tick,
that
or animal
feces
are major sources of contamination and
illness. carries and transmits
pathogens to humans
or other animals.