1. Understanding Communicable Diseases
In this chapter, you will Learn About…
Types of germs that can cause diseases.
The function of the immune system.
Some common communicable diseases.
Diseases that are transmitted by sexual contact.
Preventing the spread of communicable diseases.
Introduce the chapter objectives to students. Each objective represents a lesson within the chapter.
Clicking the Health Online icon on the left bar takes you to the URL of Glencoe’s health Web page. The Web page features a Health Inventory to help students rate their understanding of how to prevent communicable diseases.
Clicking the Foldables icon on the left bar leads to an activity. In this activity, students will create a Foldable to record the main ideas in Lesson 1 about the causes of communicable diseases.

2. Causes of Communicable Diseases
In this lesson, you will Learn About…
Types of germs that can cause disease.
What an infection is.
How germs are spread.

3. Causes of Communicable Diseases
The Vocabulary terms in this lesson are:
Disease.
Communicable disease.
Germs.
Pathogens.
Infection.
Viruses.
Bacteria.
Fungi.
Protozoa.
Click each term to display its definition.

4. Germs and Diseases
A disease is any condition that interferes with the proper functioning of the body or mind.
A communicable disease is a disease that can be spread to a person from another person, an animal, or an object.
All communicable diseases are caused by germs.
Tell students that not all diseases are communicable, that is, able to spread. Diseases such as cancer and diabetes are noncommunicable—people can’t “catch” them from someone or something else. Students will learn more about noncommunicable diseases in the next chapter.

5. Germs and Diseases (cont’d.)
The germs that are responsible for causing disease are known as pathogens.
An infection is a condition that occurs when pathogens enter the body, multiply, and damage body cells.
If the body is not able to fight off the infection, a disease develops.
Point out to students that the environment is filled with many different types of germs, most of which are harmless and some of which are helpful.

6. Types of Pathogens Types of pathogens include the following:
Viruses – The smallest and simplest disease-causing organisms
Bacteria – Tiny one-celled organisms that live nearly everywhere
Fungi – Primitive life-forms, such as molds or yeasts, that cannot make their own food
Protozoa – One-celled organisms that have a more complex structure than bacteria
Explain the types of pathogens listed on the slide using the following points:
Viruses: These organisms are responsible for a variety of health problems. Scientists have developed ways to prevent many diseases caused by viruses.
Bacteria: Many bacteria are harmless, and some are actually helpful. For example, bacteria in the intestines aid digestion. However, certain bacteria are harmful and can cause disease.
Fungi: Most fungi are harmless, but some can cause health problems.
Protozoa: While many protozoa are harmless, some types are harmful and can cause serious diseases. The diseases caused by protozoa are less common in the United States than in many other parts of the world.

7. Pathogens and the Diseases They Cause
AIDS, chicken pox, colds, hepatitis, herpes, influenza, measles, mononucleosis, mumps, polio, rabies, smallpox, viral pneumonia.
Viruses
Bacterial pneumonia, diphtheria, most foodborne, illness, gonorrhea, Lyme disease, pinkeye, strep throat, tuberculosis.
Bacteria
Athletes foot, ringworm.
Fungi
Amebic dysentery, malaria.
Protozoa

8. How Pathogens Are Spread
Pathogens can be spread in several ways:
Direct contact with others
Indirect contact, such as sneezing
Contact with animals or insects
Contaminated food and water
Contact with someone’s blood
Sexual contact
Explain how pathogens spread using the following points:
Direct contact with others. A person can get pathogens on his or her skin through direct contact with another person. For example, suppose someone who has a cold, coughs into his or her hand. If the person then shakes hands with someone else, the cold pathogens will be transferred to that person’s hand. If that person touches his or her eyes or nose, the pathogens can enter his or her body.
Indirect contact. Indirect contact leads to the spread of diseases such as colds, flu, and tuberculosis. Sharing drinking glasses, food, eating utensils, and other personal items spreads pathogens. Touching a surface—a doorknob or a telephone receiver, for example—that is contaminated with another person’s germs can also spread pathogens.
Contact with animals or insects. Animal and insect bites can also spread pathogens. For example, the bite of a rabid animal spreads rabies. The bite of a deer tick may transmit Lyme disease to humans and animals.
Contaminated food and water. Contaminated water or raw or undercooked food can spread pathogens. A mountain stream or rare hamburger can look inviting, but may spread pathogens. Illnesses that result from eating unsafe food are known as foodborne illnesses. For example, E. coli bacteria, found in raw or undercooked ground meat, can cause severe illness and even death.
Contact with someone else’s blood. Certain viruses, such as HIV, can be transmitted through contact with an infected person’s blood. This contact can occur through sharing needles that are used to inject drugs. Donated blood is screened carefully to prevent such infections from being transmitted.

9. Reviewing Terms and Facts
Define the terms disease and communicable disease.
A disease is any condition that interferes with
the proper functioning of the body or mind. A
communicable disease is a disease that can be
spread to a person from another person, an
animal, or an object.
Click to show the correct answer.

10. Reviewing Terms and Facts
What are six ways in which pathogens spread?
Direct contact with others
Indirect contact
Contact with animals or insects
Contaminated food and water
Contact with someone else’s blood
Sexual contact
Click to show the correct answer.

11. Thinking Critically
Is it more difficult to protect yourself from pathogens that are spread through direct contact or indirect contact? Explain your answer.
Sample answer: Pathogens that spread indirectly might be more difficult to combat, particularly airborne pathogens. A person may not be aware that he or she has been exposed to pathogens from indirect sources.
Accept all reasonable answers.

12. Vocabulary Review
A disease is any condition that interferes with the proper functioning of the body or mind.
Click the slide to go back to the Vocabulary Review home page.

13. Vocabulary Review
A communicable disease is a disease that can be spread to a person from another person, an animal, or an object.
Click the slide to go back to the Vocabulary Review home page.

14. Vocabulary Review
Germs are organisms that are so small that they can be seen only through a microscope.
Click the slide to go back to the Vocabulary Review home page.

15. Vocabulary Review
Pathogens are the germs that are responsible for causing disease.
Click the slide to go back to the Vocabulary Review home page.

16. Vocabulary Review
An infection is a condition that occurs when pathogens enter the body, multiply, and damage body cells.
Click the slide to go back to the Vocabulary Review home page.

17. Vocabulary Review
Viruses are the smallest and simplest disease-causing organisms.
Click the slide to go back to the Vocabulary Review home page.

18. Vocabulary Review
Bacteria are tiny one-celled organisms that live nearly everywhere.
Click the slide to go back to the Vocabulary Review home page.

19. Vocabulary Review
Fungi are primitive life-forms, such as molds or yeasts, that cannot make their own food.
Click the slide to go back to the Vocabulary Review home page.

20. Vocabulary Review
Protozoa are one-celled organisms that have a more complex structure than bacteria.
Click the slide to go back to the Vocabulary Review home page.

21. Turn the paper. Fold in half, then fold in half again.
Fold the sheet of paper along the long axis, leaving a ½” tab along the side.
Turn the paper. Fold in half, then fold in half again.
Demonstrate the activity and have students follow the steps after you. Click to view the next steps in creating the Foldable.

22. Unfold and cut the top layer along the three fold lines
Unfold and cut the top layer along the three fold lines. This makes four tabs.
Label the tabs as shown.
Demonstrate the activity and have students follow the steps after you. Click to view the next step in creating the Foldable.

23. Under the appropriate tab, summarize what you learn about each type of pathogen.
Click to return to the Chapter Overview slide.

24. Rate your understanding of how to prevent communicable diseases by taking the Health Inventory for Chapter 12 at
Students can visit to take the Health Inventory and more. Click to return to the Chapter Overview slide.