virology 2

Question 1

viral epidemiology

Answer 1

diseases in population(s) developed before recognition of a causative agent
three interdependent terms define increasing size of population

Question 2

enzootic

Answer 2

multiple, continuous transmission, disease presence in a defined population/region/time

Question 3

epizootic

Answer 3

peaks in incidence exceeding the endemic baseline
nature and degree of expected damage defines whether it is call epidemic (high damage)

Question 4

panzootic

Answer 4

worldwide epidemics

Question 5

rate

Answer 5

disease in population
number of cases/population
different diseases, different rates

Question 6

incidence or attack rate

Answer 6

number of cases over number of subjects over period of time (case:population ratio)
acute, short duration diseases
denominator: population in a time frame: thus person-years or subject-weeks

Question 7

prevalence

Answer 7

insidious onset with unknown initial date
chronic long duration diseases
no time parameters only number of cases in defined number of subject

Question 8

Data

Answer 8

acquisition difficult, incomplete and inaccurate; computation easier

Question 9

surveillance

Answer 9

continuous reporting, reportable diseases

Question 10

serological survey

Answer 10

antibody, clinical disease-silent, subclinical infection
not informative on current infections

Question 11

prospective studies

Answer 11

tracking events that are supposed to happen in the future
placebo and treatment groups
number of subjects depending on incidence
very expensive

Question 12

retrospective studies

Answer 12

cost-effective
only needing limited numbers of subjects

Question 13

incubation period

Answer 13

moment of infection to onset of clinical signs
variable

Question 14

generation time

Answer 14

from moment of infection to first day virus shedding
mostly shorter than incubation period
influence in spreading disease

Question 15

period of infectivity

Answer 15

from first day to last day of virus shedding
may or may not be longer than clinical signs
great influence in spreading disease
chronic viral diseases
distinction between these time periods is difficult
little correlation among disease, generation time, infectivity

Question 16

modes of transmission by virus

Answer 16

horizontal transmission
vertical transmission
zoonotic transmission
vector-borne transmission
iatrogenic
nosocomical

Question 17

horizontal

Answer 17

with or without vector, between the same or different host species
common vehicle: water, feed
airborne: droplets, aerosols

Question 18

direct contact:

Answer 18

licking, rubbing, biting, sexual contact
suitable for transmission of enveloped virus
lipid easier to inactivate

Question 19

indirect contact

Answer 19

fomites, eating, bedding, vehicles, surgical instruments, needles
non-enveloped virus-usually use this route of transmission

Question 20

vertical transmission

Answer 20

movement of virus from parents to their offspring during gestation via placenta, perinatally, colostrum, milk

Question 21

germline transmission

Answer 21

virus integrated into genome of ovum, transcription and replication in offspring
pass from generation to generation

Question 22

biological vector

Answer 22

virus replicate, magnify in vectors efficient transmission

Question 23

mechanical vector

Answer 23

no virus replication in vector not efficient for transmission

Question 24

zoonotic transmission

Answer 24

viral diseases transmissible under natural conditions from vertebrate animals to humans

Question 25

iatrogenic

Answer 25

patient to patient transmission under veterinary care during the interactions between the vet and the animals

Question 26

nosocomial

Answer 26

transmission occurs while the animals are in hospital or clinic under the care of veterinarians

Question 27

acute infection

Answer 27

rapid production of infectious viruses rapid resolution and elimination of infection by host acute infections do not always produce disease

Question 28

persistent infection

Answer 28

infection not cleared efficiently virus particles are produced for long period of time either continuously or intermittently for months or years

Question 29

chronic infection

Answer 29

persistent infections that are eventually cleared

Question 30

Latent infection

Answer 30

persistent infections that last the life of the host

Question 31

latency

Answer 31

viral genomes integrated into cellular genomes, not expressed no infectious progeny

Question 32

Routes of shedding

Answer 32

skin repiratory secretion saliva feces genital secretions urine milk no shedding

Question 33

skin

Answer 33

not a major route contact, abrasion, wound

Question 34

respiratory secretion

Answer 34

very important numerous disease, local, systemic shedding occur before, during after clinical signs

Question 35

saliva

Answer 35

salivary gland, oral cavity rabies, FIV

Question 36

Feces

Answer 36

GI tract virus many also without intestinal signs

Question 37

genital secretion

Answer 37

sexual activity, semen, mucus

Question 38

urine

Answer 38

rinderpest, FMD, canine hepatitis in kidney hantaviruses: mice to human

Question 39

milk

Answer 39

not an important route mammary gland replication caprine arthritis encephalitis

Question 40

no shedding

Answer 40

not all virus replications end with shedding encephalitis (CNS) retrovirus (germ line)

Question 41

host range

Answer 41

receptors on animal tissue/cells susceptible for wide range of infections or restricted infections

Question 42

susceptibility

Answer 42

ability to become infected

Question 43

permissivitiy

Answer 43

ability to replicate and produce progeny viruses