1. What Are Communicable Diseases?
When was the last time you had a cold?
How did you treat it?

2. In this lesson, you will learn to:
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

3. 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.

4. 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.

5. Causes of Communicable Diseases
Diseases by Type of Pathogen

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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.

15. 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.

16. Quick Review
Q. Which of the following is NOT a type of common pathogen and the disease it causes?
Viruses: influenza, bacteria, tuberculosis
Cortex: pathenogens, bacteria, cirrhosis
Fungi: athlete’s foot, protozoans, malaria
Rickettsias: typhus, bacteria, tuberculosis

17. A. 2. Cortex: pathenogens, bacteria, cirrhosis
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.

18. 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?
Washing your hands
Inspecting your throat for redness and mucus
Covering your mouth when you cough or sneeze
Being sure you are vaccinated against particular diseases as recommended by your physician

19. A. 2. Inspecting your throat for redness and mucus
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.

20. Q. Your risk of getting a communicable disease is less if you
Quick Review
Q. 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.
All of the above

21. A. 4. All of the above Quick Review - Answer
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.

22. 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

23. 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.

24. End of Lesson 1
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25. Quick Review - Answer
A. Correct! Types of common pathogens and the diseases they cause do NOT include: cortex—pathenogens, bacteria, cirrhosis.

26. Quick Review - Answer
You have answered the question incorrectly. Go back to try again, or click Next to view the correct answer.

27. 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.

28. Quick Review - Answer
You have answered the question incorrectly. Go back to try again, or click Next to view the correct answer.

29. 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.

30. Quick Review - Answer
You have answered the question incorrectly. Go back to try again, or click Next to view the correct answer.

31. 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.

32. Quick Review - Answer
You have answered the question incorrectly. Go back to try again, or click Next to view the correct answer.

33. 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.
A communicable disease is a disease that is spread from one living thing to another or through the environment.

34. 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.
A pathogen is an organism that causes disease.

35. 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.

36. 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.
A virus is a piece of genetic material that invade living cells to reproduce.

37. 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.
Bacteria are single-celled microorganisms.

38. 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.
Toxin is a substance that kills cells or interferes with their functions.

39. 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.
Vector is an organism, usually an arthropod, such as a tick, that
carries and transmits pathogens to humans or other animals.