exam 1

Question 1

what are the 3 parts of disease transmission?

Answer 1

interaction between the host, agent and environment

Question 2

who is the father of epidemiology and what disease did he focus on?

Answer 2

John Snow- cholera

Question 3

Typhoid Mary is an example of what type of host?

Answer 3

asymptomatic carrier

Question 4

Who discovered the use of mosquitoes as vectors?

Answer 4

Ronald ross- malaria

Walter Reed- yellow fever

Question 5

T/F knowing the agent is more important than knowing the mode of transmission

Answer 5

FALSE

knowing the mode of transmission is more important than knowing the agent

Question 6

What are the chain of events for an infectious disease?

Answer 6

pathogenic microorganism, reservoir, means of escape, mode of transmission, means of entry, host susceptibility

Question 7

what are 4 components a reservoir must have?

Answer 7

agent can live, grow, multiply and is maintained over time

Question 8

T/F: all clinically ill animals are reservoirs

Answer 8

FALSE

must be reservoir competent

Question 9

Congenital and perinatal are examples of which type of transmission?

Answer 9

vertical

Question 10

T/F: horizonal transmission can be via direct or indirect contact with reservoir

Answer 10

True

Question 11

Droplet spread and airborne are examples of which type of transmission?

Answer 11

direct horizontal transmission

Question 12

what are the 2 modes of indirect transmission?

Answer 12

Vehicle= inanimate objects
common vehicle- food, water, contaminated IV drugs
fomites- nosocomial and iatrogenic exposure with contaminated objects

Vector= living organism
mechanical- agent does not multiply
biological- multiplies in vector

Question 13

What is the difference between a latent and incubation period?

Answer 13

latent- replication but not enough to become infectious

incubation- replicating but not yet symptomatic

Question 14

what is the difference between infectious and infestation?

Answer 14

both have invasion of host but multiplication occurs in infectious and not infestation

Question 15

what is the difference between contagious and communicable?

Answer 15

contagious is by direct contact and communicable can be by direct and indirect contact

Question 16

T/F: Epidemic curves can tell you the magnitude and pattern of disease, probably source and tracking time of infection, contagiousness, if it will end of continue, incubation period

Answer 16

True

Question 17

What is the significance of outliers in the epidemic curve?

Answer 17

they can represent index case/source, early exposure or late exposure

Question 18

on an epidemic curve how is the incubation period determined?

Answer 18

it is the space between each peak in separate episodes

Question 19

what does it mean when the magnitude of a case continues to increase?

Answer 19

indicates contagious disease

Question 20

what is a propagated curve, what does it mean and is there a need to vaccinate?

Answer 20

exposure followed by a secondary and tertiary wave indicating an infectious disease and vaccinations should be used

Question 21

what is a common source single point exposure curve, what does it mean and is there a need to vaccinate?

Answer 21

all animals were exposed to the same source at the same time, it is not contagious, incubation period can be determined if agent is known, there is a sharp incline and decline and there is no need to vaccinate because it will die out on its own

Question 22

what is a common source with intermittent exposure curve, what does it mean and is there a need to vaccinate?

Answer 22

different times of exposure to dsame source, lacks pattern and vaccination is necessary because it will continuously happen

Question 23

on the epidemic curves what does the low level fluctuations mean? high peak?

Answer 23

low level= endemic

high peak= epidemic

Question 24

what are 3 factors that shape the curve

Answer 24

host- immunity, resistance, direct transmission
agent- infectiousness, latent and incubation periods, duration of infectivity
environment- important for indirect transmission

Question 25

what is a disease determinant?

Answer 25

factors that help determine the probability, distribution or severity of a disease in an animal or population

Question 26

what are primary, secondary, intrinsic and extrinsic determinants?

Answer 26

primary- necessary and must be present for disease to occur secondary- enabling factor making disease more likely intrinsic- internal process in the animal, endogenous, genetically determined extrinsic- external to animal

Question 27

what are 3 extrinsic factors?

Answer 27

the agent characteristics, the environment, vaccination ex: diet, stress, housing, climate, demographics

Question 28

what are 3 intrinsic factors?

Answer 28

genotype, breed, status of body being immune ex: sex age, breed, nutrition, immunity

Question 29

what is herd immunity?

Answer 29

infectious disease that can be contained if the populations resistance is high enough

Question 30

What percentage of human pathogens are zoonotic?

Answer 30

61%

Question 31

what is an emerging disease?

Answer 31

a previously unknown agent that emerges or a previously known agent in a new population

Question 32

What is a re-emerging disease?

Answer 32

known disease that was previously on a decline but is becoming more common

Question 33

how are diseases recognized?

Answer 33

detection of abnormal, weird or unusual by farmer or vet followed by investigation by state and federal agencies

Question 34

What are the 5 stages of disease emergence?

Answer 34

Stage 1: pathogen exclusive to reservoir Stage 2: passage to other species but no subsequent transmission (dead end host) Stage 3: passage to other species with few cycles of subsequent transmission Stage 4:passage to other species and transmission is sustained in new host Stage 5: pathogen is exclusive to new host

Question 35

What are examples of Stage 2 diseases?

Answer 35

rabies, WEEV, EEEV, west nile, H5N1

Question 36

What are examples of Stage 3 disease?

Answer 36

Mycobacterium bovis, nipah virus

Question 37

What are examples of stage 4 diseases?

Answer 37

SARS, Schmallenberg virus and H1N1

Question 38

What are examples of Stage 5 diseases?

Answer 38

HIV, measles, smallpox, dengue fever, yellow fever

Question 39

T/F: Land use changes, food agricultural systems, environment systems and human behavior are drivers for disease emergence

Answer 39

True

Question 40

What are pathogenically related factors that determine disease emergence?

Answer 40

type (virus is most emergent) mutations (antibiotic resistance, enhanced transmissibility)

Question 41

T/F: the best transmission of a disease is within the species and are more likely to transmit between closely related species rather than distant ones

Answer 41

True

Question 42

T/F: pathogenic cross between distantly related species often cause very different and more severe disease

Answer 42

True

Question 43

T/F: intensive agriculture has created a more susceptible population

Answer 43

True the animals usually have very little genetic diversity managed under the same conditions giving them the same susceptibility

Question 44

What are 3 modes of intentional release of diseases?

Answer 44

Bioterrorism- anthrax biocrimes- salmonella agroterrorism- FMD

Question 45

What are the 4 portals of entry for transboundary disease?

Answer 45

animal/animal products/animal trade vectors fomites people-travel