Epidemiology

Question 1

Virus epidemiology

Answer 1

The study of determinants, frequency, dynamics, and distribution

Question 2

Why study epidemiology of viral diseases

Answer 2

Risk of infection and/or disease in an animal or population determined by:

• characteristics of virus (genetic variation from evolution)
• Host and host pop (passive, innate, acquired resistance)
• behavioral, environmental, ecological factors that affect virus transmission from one host to another

Question 3

Role of epidemiology in viral diseases

Answer 3

Identify and/or clarify role of viruses in etiology of diseases
Understand interaction of viruses with environmental determinants of disease
Determining factors affecting host susceptibility
Studying impacts of viral disease on health, economy, and society
Unraveling modes of viral disease transmission
Studying role of infectious pathogens in pathogenesis of chronic non communicable diseases
Large scale testing of vaccines and drugs

Question 4

How that helps

Answer 4

Advancing our understanding of nature of diseases
Alerting and directing disease treatment, control, and prevention activities
Providing early warning systems and tracking the disease
Assessment of economic and social impacts of a disease
Assessment of the efficacy and cost of disease control and prevention programs

Question 5

Case fatality rate

Answer 5

Number (%) of deaths among the clinically ill animals

Question 6

Mortality rate

Answer 6

Number (%) of animals in a population that die from a particular disease over a specified time period

Question 7

Morbidity rate

Answer 7

Percentage of animals in a population that develop CS attributable to a particular virus over a defined period of time (commonly the duration of the outbreak)

Question 8

Incidence

Answer 8

The number of new cases that occur in a population over specified period of time
Measure of the occurrence of infection or disease in a pop over time.

Question 9

Prevalence

Answer 9

Number of occurrences of disease (old and new), infection, or relating attributes (antibodies) in a pap at particular point in time

Question 10

Sporadic viral diseases

Answer 10

Viral diseases occurring occasionally, singly, or in scattered instances, and in an irregular and haphazard manner

Question 11

Enzootic viral diseases (endemic in humans)

Answer 11

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

Question 12

Epizootic viral diseases (epidemic in humans)

Answer 12

Occurrence of more cases of viral diseases than expected in a given area or among a specific group of people/animals over a particular period of time
refers to peaks in disease incidence that exceed that endemic/enzootic baseline or expected incidence of disease

Question 13

Panzootic viral diseases (pandemic in humans)

Answer 13

Virus epidemic occurring over a very wide area (several countries or continents) and usually affecting large proportion of the population

Question 14

Asymptomatic carrier

Answer 14

Animals that have contracted an infectious viral disease, but display no clinical symptoms

• shed virus, transmitting disease to others
• shedding of virus may be continuous or intermittent

Question 15

Contagious disease

Answer 15

Disease that is spread from on person or organism to another by direct or indirect contact

Question 16

Period of contagiousness

Answer 16

Time during which an infected animal sheds virus

Question 17

Exotic disease

Answer 17

Disease not known to occur in a particular country of geographical area

Question 18

Methods to study epidemiology of viruses- Seroepidemiology

Answer 18

Simply denotes the use of serological data as the basis of epidemiological investigation, as determined by diagnostic serological techniques

Question 19

Methods to study epidemiology of viruses- Molecular epidemiology of viruses

Answer 19

The use of molecular biological data as the basis of epidemiological investigation of viral diseases

Question 20

Transmission of viruses

Answer 20

Horizontal 
-Contact: direct and indirect
-Vector: mechanical and biological
-Vehicle borne
-Iatrogenic
-Nosocomial
Vertical

Question 21

Horizontal (lateral) transmission

Answer 21

Spread of an infectious agent from one person/animal or group to another person/animal or group
Most are transmitted this way

Question 22

Contact transmission

Answer 22

Spread of infectious agent by direct or indirect contact

Question 23

Direct contact transmission

Answer 23

Involves actual physical contact between an infected animal and a susceptible animal (rubbing, licking, biting)
Also includes sexual contact

Question 24

Droplet transmission

Answer 24

Direct-contact
Transmission of virus in droplet nuclei (saliva or mucus) that travel less than 1 meter from the source to the susceptible host

Question 25

Indirect contact transmission

Answer 25

Occurs via fomites, such as shared eating containers, bedding, etc

Question 26

Fomite

Answer 26

Inanimate object or substance that is contaminated with infectious agent and is capable of transmitting infectious organisms from one individual to another

Question 27

Airborne transmission

Answer 27

Indirect Spread of infectious agents by droplet nuclei in dust that travel more than on meter sometimes for miles, from the infected to the susceptible host

Question 28

Vector transmission

Answer 28

Athropod-borne | Athropod vectors carry viruses from infected host to susceptible host

Question 29

Mechanical transmission

Answer 29

Passive transport of the infectious agent on the feet or other body parts of the arthropod vector

Question 30

Biological transmission

Answer 30

Infectious agent undergoes either a necessary part of its life cycle, or multiplication, in the vector before transmission to susceptible host

Question 31

Arboviruses

Answer 31

Class of viruses transmitted to humans by arthropods such as mosquitos and ticks

Question 32

Enzootic transmission cycle

Answer 32

Sylvatic/jungle cycle | Natural transmission of virus between wild animals/birds (vertebrate hosts) and primary insect vectors

Question 33

Epizootic transmission cycle

Answer 33

Rural cycle | Virus is transmitted between non-wild or domestic animals and the primary or accessory insect vectors

Question 34

Urban transmission cycle

Answer 34

Virus cycles between humans and insect vectors

Question 35

Amplifying host

Answer 35

In which the level of virus can become high enough that an insect vector such as a mosquito that feeds on it will probably become infectious

Question 36

Dead-end host/incidental host

Answer 36

Host from which infectious agents are not transmitted to other susceptible hosts Do not develop sufficient viremia to be picked up by the insect vectors

Question 37

Common-vehicle transmission

Answer 37

Includes fecal contamination of food and water supplies (fecal oral transmission) and virus contaminated meat or bone products

Question 38

Iatrogenic transmission

Answer 38

Infection that is transferred during medical or surgical practice 2 ways: -intro of pathogens by contaminated instruments (non-sterile surgical instruments, syringes) or contaminated body surface (inadequate handwashing) -intro of pathogen through contaminated prophylactic therapeutic prep

Question 39

Nosocomial transmission

Answer 39

While an animal is in a vet hospital or clinic | Hospital acquired infection

Question 40

Vertical transmission

Answer 40

Usually used to describe infection that is transferred from dam to embryo, fetus, or newborn before, during, or shortly after parturition (colostrum, milk, or fecal contamination of teats)

Question 41

Zoonosis

Answer 41

Describes infections that are transmissible from animals to humans

Question 42

Physical stability of virus

Answer 42

Viruses that are transferred by respiratory route have low environmental stability, Transmitted fecal-ral have higher

Question 43

Herd immunity

Answer 43

Occurs when the vaccination fo a significant large portion of a population provides measure of protection for individuals who have not developed immunity

Question 44

Incubation period

Answer 44

Interval between infection and onset of CS | Many diseases have period during which animals are infectious before becoming sick

Question 45

Prodromal period

Answer 45

First signs and feelings of illness after incubation period Period of early symptoms of a disease occurring after incubation period and just before appearance of the characteristic symptoms of disease

Question 46

Acute period

Answer 46

When disease is at its height | severe CS

Question 47

Decline period

Answer 47

Period when CS begin to subside

Question 48

Convalescent period

Answer 48

Body gradually returns to pre-diseases state, and health restored