Lecture 2 8/22/24

Question 1

What are the different determinants that affect the agent of disease?

Answer 1

-viability
-host range
-infectious dose
-infectivity
-pathogenicity
-virulence

Question 2

What is viability?

Answer 2

ability to withstand environmental stress

Question 3

What is the importance of host range?

Answer 3

the more hosts an agent can infect, the better the survival for the agent, increasing the likelihood for continued disease outbreak

Question 4

What is infectious dose?

Answer 4

the quantity of agent necessary to establish infection

Question 5

What is infectivity?

Answer 5

ability to enter, multiply, and produce immune response in a host

Question 6

What is pathogenicity?

Answer 6

ability of the agent to produce clinical disease

Question 7

What is virulence?

Answer 7

degree of pathogenicity of an agent, measured as mortalities from the disease/case fatality rate

Question 8

What is resistance?

Answer 8

-the ability of an individual to defend itself against a pathogen
-can be innate or inherent/genetic
-can be acquired natural or artificial resistance/immunity

Question 9

What is susceptibility?

Answer 9

state of being readily affected by the pathogen

Question 10

What is ID50?

Answer 10

number of pathogen cells required to cause active infection in 50% of exposed animals

Question 11

What is LD50?

Answer 11

number of pathogen cells required to cause death in 50% of exposed animals

Question 12

What is immunity?

Answer 12

protection against disease by specific substances, including antibodies and reactive lymphocytes

Question 13

What are the different determinants that affect the host of disease?

Answer 13

-species
-breed
-age
-sex
-physiology

Question 14

How does species impact a host’s response to disease?

Answer 14

-differences in clinical response and resistance
-agent may be broad, or be restricted to range of susceptible host species

Question 15

What is important about species that are subclinically infected by an agent?

Answer 15

they can serve as a reservoir/source of infection

Question 16

How does disease incidence differ between young and old animals?

Answer 16

-young animals have a higher incidence of infectious diseases
-old animals are more likely to develop immunosuppressive conditions, arthritic conditions, and diseases with long incubation periods

Question 17

What are the different determinants that affect the environment of disease?

Answer 17

-location
-climate and weather
-husbandry and management