Chapter 12: Epidemiology of Infectious Diseases

Question 1

What does the 3 factor epidemiologic triangle consist of?

Answer 1

• Agent
• Host
• Environment

Question 2

What is an agent?

Answer 2

a factor that must be present for an infection to occur

Question 3

What are characteristics of infectious disease agents?

Answer 3

• infectivity (Ingrid)
• pathogenicity (Payton)
• virulence (Victoria)
• toxigenicity (Toni)
• resistance (Renee)
• antigenicity (Anne)

Question 4

Antigenicity?

Answer 4

the ability of the agent to induce antibody production in the host

Question 5

Host?

Answer 5

the person or animal who is capable of developing an infection following exposure to an agent

Question 6

immunity?

Answer 6

concerns the resistance of the host to a disease agent. can be either passive/active or natural/artificial

Question 7

active immunity?

Answer 7

when exposure to a disease organism triggers the immune system to produce antibodies to that disease

• long lasting but takes time to develop
• Alex and Imogen were at the race line ready to start. As soo as they both heard the gunshot, it triggered them to begin running

Question 8

passive immunity?

Answer 8

when a person is given antibodies to a disease rather than producing them through their own immune system

Question 9

natural active immunity?

Answer 9

results from an infection by the agent; someone is exposed to a live pathogen, develops the disease, and becomes immune

Question 10

artificial active immunity? (vaccine induced immunity)

Answer 10

results from an injection with a vaccine that stimulates antibody production in the host. the person can build resistance to a disease following an immunization

Question 11

natural passive immunity?

Answer 11

Preformed antibodies during pregnancy are transferred across the placenta to the fetal bloodstream to produce short-term immunity in the newborn. immunity from mother to child

Question 12

artificial passive immunity?

Answer 12

Preformed antibodies against a specific disease are administered to an exposed individual to confer protection against a disease. injected antibodies created w/in a different person or animal

Question 13

What is the environment?

Answer 13

the domain where the disease causing agent may exist, survive, or originate. In some instances, it serves as a
reservoir or niche that fosters the survival of infectious disease agents

Question 14

Modes of transmission? (of diseases)

Answer 14

• airborne
• droplet
• direct contact
• vehicle (food, etc.)
• vector (insects, animals, etc.)

Question 15

direct transmission of diseases?

Answer 15

the spread of infection through physical (person to person) contact
-sexually transmitted (touching,kissing,sex, etc)

Question 16

indirect transmission?

Answer 16

the spread of an infection though an intermediary source: vehicles, vectors, and fomites

Question 17

vehicle spread?

Answer 17

a method for transmitting an infectious disease agent. spread by food, water, air, etc.

Question 18

what is a vehicle?

Answer 18

the medium that contains the agent

Ex: water, food, infected blood

Question 19

what is a fomite?

Answer 19

an inanimate object laden w/ disease causing agents

Ex: doorknob, clothing, etc.

Question 20

what is a vector?

Answer 20

an animate, living insect or animal involved w/ transmission of the disease agent

Question 21

portals of exit?

Answer 21

sites where infectious agents may leave the body. includes respiratory passages, the alimentary canal, the genitourinary openings, and skin lesions

Question 22

What is an inapparent (subclinical) infection?

Answer 22

one that hasn’t penetrated the clinical horizon. it diesn’t have clinically obvious symptoms.

Question 23

Incubation period?

Answer 23

the time interval between exposure to an infectious agent and the appearance of the first signs or symptoms of disease

Question 24

Herd immunity?

Answer 24

the immunity of a pop., group, or community against an infectious agent when a large proportion of individuals are immune. Happens when immune people prevent the spread of a disease to unimmunized people

Question 25

Generation time?

Answer 25

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

Question 26

Colonization?

Answer 26

the multiplication of an infectious agent on the surface of the body w/o invoking a tissue or immune response

Question 27

Infestation?

Answer 27

the presence of a living infectious agent on the body’s exterior, on which a local reaction may appear

Question 28

iceberg concept of infection?

Answer 28

page 1155*

Question 29

secondary attack rate?

Answer 29

measure the spread of a disease w/in a household or similar circumscribed unit. pertains to the spread of disease in a family, household, dwelling unit, dormitory, or similar circumscribed group.

Question 30

case fatality rate? (CFR)

Answer 30

a proportion formed by the # of deaths caused by a disease among those who had a the disease; expressed as a percentage

Question 31

basic reproductive rate (R0)?

Answer 31

a measure of the # of infections made on average by by an infected individual in the early stages of an epidemic when all contacts are susceptible

Question 32

Virulence?

Answer 32

an agent’s capacity to induce disease in the host

Question 33

Infectivity?

Answer 33

the capacity of the agent to enter and multiply in a susceptible host and thus produce infection or disease.

Question 34

Pathogenicity?

Answer 34

concerns the capacity of the agent to cause overt disease in the infected host

Question 35

Toxigenicity?

Answer 35

denotes the capacity of the agent to produce a toxin or poison

Question 36

Resistance?

Answer 36

signifies the ability of the agent to survive adverse environmental conditions

Question 37

Cholera is another example of what kind of disease?

Answer 37

a water or foodborne disease; an acute enteric disease w/ sudden onset, occasional vomiting, rapid dehydration, acidosis, and circulatory collapse

Question 38

What are STDs or STIs?

Answer 38

Sexually transmitted disease/infections. Diseases spread by sexual activity or sexual intercourse

Question 39

What are the 3 stages of HIV?

Answer 39

• acute
• chronic
• AIDS

Question 40

Vaccine preventable diseases?

Answer 40

infectious diseases that vaccinations can aid in controlling
-Measles
Chicken pox
-Hepatitus A/B
-Pertusis

Question 41

What is zoonosis?

Answer 41

a disease that, under natural conditions, can be spread from vertebrate animals to humans.

Question 42

Arboviral diseases?

Answer 42

diverse group of diseases that involve transmission of arboviruses

Question 43

emerging/re-emerging infections?

Answer 43

infectious diseases that have been identified or have come back