Communicable Diseases
Study Guide
Lesson 1, Preventing the Spread of Disease Communicable diseases are diseases
that can be passed from one person to another. These diseases are caused by germs.
Two common types of germs are bacteria and viruses. Germs are spread by direct or
close contact with an infected person, contact with an infected insect or animal, or
contact with contaminated water or food. Practicing good health habits and behaviors
can prevent the spread of communicable disease.
Lesson 2, The Body’s Defenses Against Germs Immunity is the body’s
resistance to germs. Skin and body fluids such as saliva and tears keep most germs
from entering the body. The body also has other immune responses to germs. Fever,
for example, is a general reaction to infection. Many germs are destroyed by higher-thannormal body temperatures. The lymphatic system, a network of vessels and
nodes (small lumps of tissue) throughout the body, carries a germ-fighting fluid called
lymph. Having a disease is one way of becoming immune to that disease. Another
way is through a vaccine, a preparation of dead or weakened germs. Vaccines are
injected into the body to produce germ-fighting antibodies.
Lesson 3, Common Communicable Diseases The cold is the most common
communicable disease. Colds are caused by over a hundred viruses, so there are no
vaccines to treat them. Following a healthy lifestyle is the best way to prevent colds.
Influenza, the “flu,” is another common communicable disease. There are flu
vaccines, but they are not completely effective because the virus that causes influenza
keeps changing. The treatment for both colds and flu includes getting plenty of rest,
drinking a lot of fluids, eating a balanced diet, and taking medicines to lessen
symptoms.
Lesson 4, Sexually Transmitted Diseases A sexually transmitted disease (STD)
is an illness that is passed from one person to another through sexual contact.
Although many STDs can be treated, the only sure way to avoid most STDs is to
abstain from, or avoid, sexual contact. Teens can use smart actions and words to
support themselves in their decision to choose abstinence. The most common STDs
are chlamydia, gonorrhea, genital warts, genital herpes, and syphilis. Every year,
there are about 12 million new STD cases. Two-thirds of those cases occur among
teens and young adults.
Lesson 5, HIV/AIDS AIDS, or acquired immunodeficiency syndrome, is a deadly
disease. AIDS interferes with the body’s natural ability to fight infection. It is caused
by a virus known as HIV, or human immunodeficiency virus. Someone with HIV in
his or her blood may appear to be healthy, yet pass the virus on to others. Symptoms
of AIDS may not appear for years. There is no drug available that kills HIV or cures
AIDS. HIV is passed from person to person in body fluids such as blood, semen, and
vaginal secretions. To prevent the spread of HIV, avoid sexual contact and illegal
drugs, especially those taken by sharing needles.