1. Common Communicable Diseases
A communicable disease is a disease caused by a pathogen (a disease-causing organism) that can be transmitted to another person. The common cold, for example, is caused by pathogens. A noncommunicable disease is a disease which cannot be transmitted from one person to another, such as heart disease.

2. Disease-Causing Pathogens
Viruses- are the smallest pathogens, programmed to infect only certain body cells. When a virus enters a cell, it directs the cell to make more viruses. Some viral diseases are the common cold, measles, chicken pox, influenza, and herpes.
Bacteria- are single-celled microorganisms. There are more than 1000 kinds of bacteria, but only about 100 are known to cause disease. Some bacterial diseases are strep throat, tuberculosis, syphilis, gonorrhea, and Lyme disease.

3. Disease-Causing Pathogens (cont.)
3. Rickettsia- are pathogens that grow inside living cells and resemble bacteria (but are much smaller than bacteria). Two diseases they cause are Rocky Mountain spotted fever and typhus.
4. Fungi- are single-celled or multicellular plantlike organisms, such as yeast and molds. Fungi can cause diseases of the skin, mucous membranes, and lungs. Athlete’s foot, ringworm, jock itch, and nail infections are examples of diseases caused by fungi.

4. Disease-Causing Pathogens (cont.)
5. Protozoa- are tiny, single-celled parasites. Some disease caused by protozoa are malaria, African sleeping sickness, and dysentery. Giardia is a protozoan that might infect people who drink impure water. Giardiasis is a disease that causes intestinal pain and diarrhea.

5. How Pathogens Are Spread
1. Direct Contact- Examples include kissing, sexual intercourse, blood transfusions, open sores, touching infected body fluids.
2. Contact with pathogens in the air- When an infected person coughs or sneezes, pathogens are released into the air. When inhaled by another person, that person may become infected.

6. How Pathogens Are Spread (cont.)
3. Contact with contaminated objects- A person can become infected by using objects touched by an infected person, such as a toothbrush, pen or pencil, eating utensil, or clothing.
4. Through contact with animals and insects- A person can become infected when bitten by an animal or insect. An insect can pick up a pathogen when it lands on sewage and deposit it on food. People might eat the food and become infected.

7. How Pathogens Are Spread (cont.)
5. Contact with contaminated food or water- As you well know, pathogens may be found in either food or water. That is why it is so important to wash your hands before handling food. Water is purified before it gets to your tap for the same reason- to kill pathogens which could cause disease. Chlorine and fluoride are used for this purpose.

8. How The Body Defends Itself Against Pathogens
Your body has several ways to protect itself from pathogens:
Skin- Unbroken skin prevents pathogens from entering the body. The outer layer of skin (the dead cells), is removed when you bathe. In this way, bathing rids the body of pathogens.
Tears, Saliva, and Perspiration- All of these contain chemicals that kill pathogens.

9. How The Body Defends Itself Against Pathogens (cont.)
3. Mucous Membranes- Mucous found in the nose and throat trap and destroy pathogens.
4. Stomach acids- Some pathogens are destroyed by saliva when they enter the mouth. The pathogens that make it to the stomach are killed by stomach acids.
5. Fever- Since many pathogens cannot live in a high temperature environment, running a fever is helpful in fighting certain infections.

10. How The Body Defends Itself Against Pathogens (cont.)
6. The Immune System- Is the body system that contains cells and organs that fight disease. T-Cells are white blood cells that regulate the action of the immune system. Phagocytes are white blood cells that surround and kill pathogens by ingesting them. B-Cells are cells that produce antibodies. An antibody is a protein that helps fight infection.

11. Active Immunity
Immunity is resistance to disease. Active immunity is a resistance to disease due to the production of antibodies. You develop active immunity from having a disease or from receiving a vaccine. A vaccine consists of dead or weakened pathogens that are introduced to the body in order to give a person more immunity.

12. Passive Immunity
Passive immunity is the immunity that results from introducing antibodies into the bloodstream. The antibodies might be from another person’s blood. This type of immunity is short term. It is used when the risk of developing a disease is immediate.

13. Reducing The Risk Of Communicable Diseases
Avoid being with people who are ill.
Stay home from school when you are ill.
Practice abstinence.
Do not touch sores on another person’s body.
Use universal precautions when exposed to another person’s body fluids.
Cover your mouth and nose when sneezing or coughing.

14. Reducing The Risk Of Communicable Diseases (cont.)
7. Do not share personal items such as towels, toothbrushes, and eating utensils.
8. Do not share a needle for ear or body piercing.
9. Check with your physician if bitten by an animal.
10. Keep animals and insects away from foods.

15. Reducing The Risk Of Communicable Diseases (cont.)
11. Wash your hands with soap and water after using the restroom, and especially before eating.
12. Keep fingers and hands away from the nose, eyes, and mouth.
13. Follow precautions to prevent foodborne illness.
14. Get appropriate vaccines.