WEEK 6: INFECTION AGENTS

Question 1

Define the following terms
1.Disease
2.Infectious disease
3.Infection

Answer 1

1.Disease
– A pathological condition of body parts or tissues characterized by an identifiable group of signs and symptoms.

2.Infectious disease
– disease caused by an infectious agent such as a bacterium, virus, protozoan, or fungus that can be passed on to others.

-Disorders that are caused by organisms, usually microscopic in size, such as bacteria, viruses, fungi, or parasites that are passed, directly or indirectly, from one person to another.

3.Infection
– occurs when an infectious agent enters the body and begins to reproduce; may or may not lead to disease.

Question 2

Define the following terms;

1.Pathogen
Host
Virulence
Endemic
Epidemic
Pandemic

Answer 2

1.Pathogen
– an infectious agent that causes disease.

Host – an organism infected by another organism.

2.Virulence
– the relative ability of an agent to cause rapid and severe disease in a host.

3.Endemic
- Transmission occur, but the number of cases remains constant

4.Epidemic
-The number of cases increases

5.Pandemic
- When epidemics occur at several continents – global epidemic

Question 3

Describe how infectious agents cause diseases.

Answer 3

*Direct tissue invasion- Prions

*Toxins, enzymes C. Tetani- Tetanospasmin

*Persistent or latent infection: MTB

*Altered susceptibility to drugs: MRSA,MDR-TB

*Immune suppression: HIV

*Immune activation (cytokine storm): H5N1-avian influenza, smallpox, Corona virus

Question 4

Describe how infectious agents/diseases are transmitted.

Answer 4

1.Contact transmission
-Direct
-Indirect

2.Vehicle
-Water borne
-Air borne
-Food borne

3.Vector transmission
-mechanical
-Biological

Question 5

Outline Agents that cause infectious diseases.

Answer 5

Fungi
Virus
Bactria
Protozoa
Worms