Exam1 epidemiology Flashcards by Cheryl Hausle

How was SARS transmitted to people? (or so they think)

a. from bats and pigs
b. from bats and cows
c. from bats and civets
d. from cows and pigs

c. from bats and civets

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What is virus epidemiology?

study of determinants, frequency, dynamics, and distribution of viral diseases in populations

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Case fatality rate is :

a. number of clinically ill animals in the population
b. number of deaths among the clinically ill
c. number of animals in a population that die from a disease over a period of time.
d. percentage of animals in a population that develop clinical signs attributable to the virus

b. number of deaths among the clinically ill

population = 100
sick = 25
dead = 10

case fatality rate = 10/25 x 100 = 40%

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Mortality rate is :

c. number of animals in a population that die from a disease over a period of time.

population = 100
sick = 25
dead = 10

mortality rate -= 10/100 x 100 = 10%

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Morbidity rate is :

d. percentage of animals in a population that develop clinical signs attributable to the virus

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Incidence is :

a. number of occurrences of disease, infection in population over a specified period of time
b. number of new cases that occur in a population over a specified period of time

b. number of NEW cases that occur in a population over a specified period of time

aka attack rate

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Prevalence is :

a. number of occurrences of disease, infection in population over a specified period of time
b. number of new cases that occur in a population over a specified period of time

a. number of occurrences of disease, infection in population over a specified period of time

difficult to measure incidence of chronic diseases

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Which of the following best describes a pandemic disease?

a. normally occurs in a given geographic area
b. epidemic that occurs more than one continent at the same time
c. disease that occurs more frequently than usual for a geographic area or group of people or animals
d. occurs infrequently at no predictable time scattered over large area or population

b. epidemic that occurs more than one continent at the same time

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Which of the following best describes an epidemic disease?

c. disease that occurs more frequently than usual for a geographic area or group of people or animals

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Which of the following best describes an endemic disease?

a. normally occurs in a given geographic area

ex : DENV - Dengue virus is endemic in most of the world’s tropical and subtropical areas

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Which of the following best describes a sporatic disease?

d. occurs infrequently at no predictable time scattered over large area or population

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What is an exotic disease?

disease not known to occur in a particular area.

ex : if ebola, that usually occurs in africa, came to the US

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What is a sporatic viral disease?

a. constant presence of a viral disease within a given geographic area or population group
b. occurs occasionally, or in irregular/haphazard manner
c. occurrence of more cases of viral disease than expected in a given area or among a group.
d. virus epidemic occurring over a very wide area, usually affecting a large proportion of the population.

a. constant presence of a viral disease within a given geographic area or population group

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What is an enzootic viral disease?

a. constant presence of a viral disease within a given geographic area or population group

ex : Louping III, tick-bourne viral disease of sheep, is enzootic in British isles

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What is an epizootic viral disease?

c. occurrence of more cases of viral disease than expected in a given area or among a group.

epidemic in humans

refers to peaks in disease incidence that exceeds enzootic baseline or expected incidence of disease

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What is an panzootic viral disease?

d. virus epidemic occurring over a very wide area, usually affecting a large proportion of the population.

pandemic in humans

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T/F a carrier animal displays clinical signs

FALSE

a carrier animal displays NO clinical signs

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Which of the following are NOT an example of a carrier?

a. incubatory
b. convalescent
c. inapparent
d. mechanical

d. mechanical

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what is an incubatory (acute) carrier?

a. animals that shed virus during recovery from disease
b. animals that shed virus during incubation period of the disease
c. carrier state may exist in an animal with an infection that is apparent throughout its course

b. animals that shed virus during incubation period of the disease

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what is an convalescent (chronic) carrier?

a. animals that shed virus during recovery from disease

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what is an inapparent carrier?

c. carrier state may exist in an animal with an infection that is apparent throughout its course

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In african horse sickness, cases by orbivirus, the virus travels from zebra to culicoides to horse. Which is the inapparent carrier?

a. zebra
b. culicoides
c. horse

a. zebra - no clinical signs

culicoides - vector
horse - host

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Define contagious disease.

disease that is spread from one person or organism to another by direct or indirect contact

period of contagiousness

time during which an infected animal sheds virus

what is a reservoir?

habitat in which an infectious agent normally lives, grows, and multiplies. may be animate or inanimate

seroepidemiology : a. determines prevalence of particular infections b. evaluate eradication and immunization programs c. makes it possible to determine clinical to subclinical infection d. all of the above

d. all of the above

Most viruses are transmitted : a. horizontally b. vertically

a. horizontally

T/F contact transmission is the spread of infectious agent by direct contact only.

FALSE | contact transmission is the spread of infectious agent by direct contact AND INDIRECT CONTACT.

Droplet Transmission is transmission of virus in a droplet nuclei that travel : a. more than 1 meter from the course b. less than one meter from the course

b. less than one meter from the course

Airborne Transmission is transmission of virus in a droplet nuclei that travel : a. more than 1 meter from the course b. less than one meter from the course

a. more than 1 meter from the course droplets less than 5um remain in the air for prolonged periods

What is an example of vector mechanical transmission of a virus? a. passive transport of the infectious agent on the feet or body parts of arthropod vector b. infectious agent undergoes either a necessary part of its life cycle or multiplication in vector before transmission to susceptible host

a. passive transport of the infectious agent on the feet or body parts of arthropod vector b is a mechanical vector

T/F mosquitos or other biting insects may serve as mechanical vectors for fowlpox virus.

true

What happens to viruses in winter months in temperate climates when arthropod vectors are inactive?

overwintering! - transovarial transmission - trans-stadial transmission

What is transovarial transmission? a. virus transmitted from larva or nymph to next stage of development b. virus is transmitted from mother tick through infected eggs

b. virus is transmitted from mother tick through infected eggs

What is trans-stadial transmission? a. virus transmitted from larva or nymph to next stage of development b. virus is transmitted from mother tick through infected eggs

a. virus transmitted from larva or nymph to next stage of development NOT vertical transmission ex : tick-borne flaviviruses

T/F arboviruses are often transmitted by ticks or mosquitos

true. arboviruses have a complex lifecycle

Enzootic cycle is : a. transmission between non-wild or domestic animals and the primary of accessory insect vector b. natural transmission of virus between wild animals/birds and primary insect vector c. virus cycle between human and and insect vectors

b. natural transmission of virus between wild animals/birds and primary insect vector

Epizootic cycle is : a. transmission between non-wild or domestic animals and the primary of accessory insect vector b. natural transmission of virus between wild animals/birds and primary insect vector c. virus cycle between human and and insect vectors

a. transmission between non-wild or domestic animals and the primary of accessory insect vector

Urban cycle is : a. transmission between non-wild or domestic animals and the primary of accessory insect vector b. natural transmission of virus between wild animals/birds and primary insect vector c. virus cycle between human and and insect vectors

c. virus cycle between human and and insect vectors

What is an amplifying host? a. host in which infectious agents are not transmitted to other susceptible hosts b. host in which the level of virus can become high enough that an insect vector that feeds on it will probably become infectious. c. arthropod that acquires virus from an infected wild animal and transmits the agent to human or secondary host.

b. host in which the level of virus can become high enough that an insect vector that feeds on it will probably become infectious.

What is an dead-end/incidental host? a. host in which infectious agents are not transmitted to other susceptible hosts b. host in which the level of virus can become high enough that an insect vector that feeds on it will probably become infectious. c. arthropod that acquires virus from an infected wild animal and transmits the agent to human or secondary host.

a. host in which infectious agents are not transmitted to other susceptible hosts

What is a bridge vector? a. host in which infectious agents are not transmitted to other susceptible hosts b. host in which the level of virus can become high enough that an insect vector that feeds on it will probably become infectious. c. arthropod that acquires virus from an infected wild animal and transmits the agent to human or secondary host.

c. arthropod that acquires virus from an infected wild animal and transmits the agent to human or secondary host.

What is common-vehicle transmission?

fecal contamination of food and water supply....think of the cows that all drink out of the common water trough

What is iatrogenic transmission?

infection transferred during medical or surgical practice

Where does nosocomial transmission occur? a. in a contaminated swamp b. contaminated soil c. in a vet clinic d. at home

c. in a vet clinic ex : parvovirus

T/F vertical transmission is usually used to describe infection transferred from dam to fetus before, during, or shortly after parturition.

true. contamination of colostrum, milk, feces, or teats

Which of the following are examples of vertical transmission of viruses? a. retroviruses - proviral DNA integrated into DNA of germ line of fertilized egg b. cytomegaloviruses - transmitted to fetus via placenta c. herpesvirus - transmitted during passage through birth canal d. all of the above

d. all of the above vertical viruses are transmitted via colostrum and milk

Which of the following would be least likely to be caused by vertical transmission of a virus? a. early embryonic death b. congenital disease c. diffuse rash covering the abdomen d. congenital defects

c. diffuse rash covering the abdomen

T/F viruses that are transmitted by the respiratory route have higher environmental stability than by fecal-oral route.

FALSE | viruses that are transmitted by the respiratory route have LOWER environmental stability than by fecal-oral route.

Which of the following is NOT a determinant of disease? a. etiology b. host factor c. environment d. pathogen

a. etiology

What is herd immunity?

form of immunity that occurs when the when the vaccination of a significant portion of a population provides protection for individuals who have not developed immunity

What period is not present in some viruses? a. incubation and acute b. prodormal and convalescent c. decline and prodromal d. acute and prodormal

b. prodormal and convalescent

What is the incubation period? a. first signs of feeling of illness. b. when disease is at its height. c. interval between infection and onset of clinical signs d. period when clinical signs begin to subside

c. interval between infection and onset of clinical signs

What is the prodromal period? a. first signs of feeling of illness. b. when disease is at its height. c. interval between infection and onset of clinical signs d. period when clinical signs begin to subside

a. first signs of feeling of illness.

What is the acute period? a. first signs of feeling of illness. b. when disease is at its height. c. interval between infection and onset of clinical signs d. period when clinical signs begin to subside

b. when disease is at its height.

d. period when clinical signs begin to subside

What is the convalescent period?

body gradually returns to its pre-disease state and health is restored.