35.1 Infectious Disease

Infectious diseases can be caused by viruses, bacteria, fungi, “protists,” and parasites.

Some diseases are spread through coughing, sneezing, physical contact, or exchange of body fluids. Some diseases are spread through contaminated water or food. Still other diseases are spread to humans from infected animals.

• infectious disease (1010)

• Koch's postulates (1011)

• germ theory of disease (1010)

• zoonosis (1013)

• vector (1013)

35.2 Defenses Against Infection

Nonspecific defenses include the skin, tears and other secretions, the inflammatory response, interferons, and fever.

The immune system's specific defenses distinguish between “self” and “other,” and they inactivate or kill any foreign substance or cell that enters the body.

The specific immune response has two main styles of action: humoral immunity and cell-mediated immunity.

• inflammatory response (1014)

• antigen (1016)

• antibody (1016)

• histamine (1014)

• humoral immunity (1016)

• interferon (1015)

• cell-mediated immunity (1019)

• fever (1015)

• immune response (1016)

35.3 Fighting Infectious Disease

Vaccination stimulates the immune system with an antigen. The immune system produces memory B cells and memory T cells that quicken and strengthen the body's response to repeated infection.

Antibodies produced against a pathogen by other individuals or animals can be used to produce temporary immunity.

Public health measures help prevent disease by monitoring and regulating food and water supplies, promoting vaccination, and promoting behaviors that avoid infection.

Antibiotics can kill bacteria, and some antiviral medications can slow down viral activity.

Two major reasons for the emergence of new diseases are the ongoing merging of human and animal habitats and the increase in the exotic animal trade.

Misuse of medications has led to the re-emergence of diseases that many people thought were under control.

• vaccination (1020)

• passive immunity (1020)

• active immunity (1020)

35.4 Immune System Disorders

A strong immune response to harmless antigens can produce allergies, asthma, and autoimmune disease.

When the immune system attacks the body's own cells, it produces an autoimmune disease.

In 1983, researchers identified the cause of AIDS—a virus they called human immunodeficiency virus (HIV).

The only no-risk behavior with respect to HIV transmission is abstinence from sexual activity and intravenous drug use.

• allergy (1024)

• asthma (1024)

Think Visually Make a flowchart that shows what occurs during the specific immune response. (Hint: Refer to Figure 35–11.)