Module 2 - Immunity

Question 1

Infectious diseases are the causes of…

Answer 1

Morbidity and mortality in the U.S. and worldwide.

Question 2

In 2005, which diseases were the eighth leading cause of death in the U.S.?

Answer 2

Influenza and pneumonia

Question 3

In total, infectious or parasitic diseases account for almost…
And respiratory infections account for…

Answer 3

Infectious or parasitic diseases account for almost 20% of mortality worldwide while respiratory infections account for 7% of mortality worldwide.

Question 4

What do Epidemiologists use to stop or prevent outbreaks?

Answer 4

The Epidemiologic Triangle

Question 5

What are the three major points of the Epidemiologic triangle?

Answer 5

Agent (the cause of the disease or condition), the host (the organism that harbors the disease), and the environment (the location where the disease-causing agents exist, survive, or originate).

Question 6

How do we stop the outbreak or spread of a disease based on the Epidemiological Triangle?

Answer 6

We must break or disconnect one leg of the triangle (agent, host, or environment).

Question 7

Define immunity. What are the two ways in which a host obtains immunity?

Answer 7

Refers to the host’s ability to resist infection by the agent.

There are two ways in which a host obtains the ability to resist an infection: Innate immunity & Adaptive immunity.

Question 8

Define adaptive immunity

Answer 8

Adaptive immunity may be obtained through natural or artificial exposure to an agent

May be either active or passive

Question 9

How is adaptive immunity subdivided?

Answer 9

It can either be active or passive. It is subdivided based on how the immunity was introduced, either naturally acquired or artificially acquired.

Question 10

Naturally acquired immunity…

Answer 10

occurs through contact with a disease-causing agent, when the contact was not deliberate.

Question 11

Artificially acquired immunity…

Answer 11

develops only through deliberate actions such as vaccination.

Question 12

What is active immunity? How can it be acquired?

Answer 12

Immunity that the host has developed as a result of natural infection with a microbial agent (usually of long duration, measured in years).

Also can be acquired from an injection of a vaccine that contains an antigen.

Question 13

What is an antigen?

Answer 13

A substance that stimulates antibody formation, e.g., a microbial agent.

Question 14

What is passive immunity? How can it be acquired? What are some examples?

Answer 14

Immunity acquired from antibodies produced by another person or animal.

Example 1: a newborn infant’s natural immunity conferred transplacentally from its mother.
Example 2: immunity conferred by injections of antibodies contained in immune serums.
Usually of short duration (measured in days to months).

Question 15

What is innate immunity?

Answer 15

Innate immunity (a.k.a. Nonspecific immunity) refers to the natural resistances that a person is born with.

Question 16

What are some physical barriers and internal defenses of the innate immune system?

Answer 16

Physical barriers: skin, hair, cilia, mucus membranes, digestive enzymes in mouth, stomach acids, etc..

Internal defenses: inflammatory responses, complement proteins, phagocytic cells, natural killer (NK) cells

Question 17

What are vaccines? What do they contain and how are they made?

Answer 17

Vaccines are a biological preparation that provides active acquired immunity to a particular disease.

A vaccine typically contains an agent that resembles a disease-causing microorganism. Is often made from weakened or killed forms of the microbe.

Question 18

What do antigens from the vaccine do?

Answer 18

Antigens from the vaccine trigger the immune system to create antibodies against the microbe.

Question 19

The agent stimulates the body’s immune system to…

Answer 19

• recognize the agent as a threat and destroy it.
• keep a record of it so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.

Question 20

What is the Immune Response Time Course

Answer 20

Formation of immunological memory:

• reinfection at later time points leads to a rapid increase in antibody production and effector T cell activity.
• later infections can be mild or even unapparent.

Question 21

Vaccine-Preventable Diseases:

Answer 21

Conditions that can be prevented by vaccination (immunization).
Examples include: 
- Diphtheria 
- Tetanus
- Whooping cough 
- Hepatitis A and B

Question 22

What is herd immunity?

Answer 22

The resistance of an entire community to an infectious agent as a result of the immunity of a large proportion of individuals in that community to the agent.

Question 23

Host characteristics:

Answer 23

• Immunity
• Incubation Period
• Subclinical illness
• Generation time
• Carrier status

Question 24

What is incubation period?

Answer 24

Time interval between invasion by an infectious agent and the appearance of the first sign or symptom of the disease.

Question 25

What is subclinical illness? How about an example?

Answer 25

An infection that does not show obvious clinical signs or symptoms.
Also called an inapparent infection.

Example: hepatitis A infections among children.

Question 26

What is Generation time?

Answer 26

The time interval between lodgment of an infectious agent in a host and the maximal communicability of the host.

Question 27

What is carrier status?

Answer 27

“A person or animal that harbors a specific infectious agent without discernible clinical disease, and which serves as a potential source of infection.”

Question 28

Define Autoimmune Disease.

Answer 28

Is a pathological state arising from an abnormal immune response of the body to substances and tissues that are normally present in the body.

Question 29

What are three characteristic effects of autoimmune disease and how can it be treated?

Answer 29

Three characteristic effects:
1. Damage to or destruction of tissues 
2. Altered organ growth 
3. Altered organ function 
Treatment with immunosuppression—medication that decreases the immune response.

Question 30

What causes allergies?

Answer 30

Caused by a hypersensitivity of the immune system to an “allergen” - something in the environment (eg. pollen, insect stings, food) that causes little to no problem in most people.

Question 31

Examples of allergies and its symptoms and treatments.

Answer 31

Examples include: Hay fever, Food allergies, Allergic asthma, Anaphylaxis

Symptoms include red eyes, an itchy rash, runny nose, shortness of breath, or swelling.

Treatments include avoiding known allergens and the use of medications such as steroids and antihistamines.