Epidemiology of Infectious Disease

Question 1

Definition

the occurrence of diseases in excess of what would normally be expected in a community or geographical area

Answer 1

Epidemic

Question 2

Definition

a number that represents when the population is completel susceptible. It indicates whether the invasion of the pathogen can give rise to an exponentially growing epidemic

Answer 2

Basic reproductive number (Ro)

Question 3

How is knowledge of the incubation period used in clinical management?

Answer 3

To predict disease severity, shorter incubation period is associated with severe complications

Question 4

How are severity of infection and dose related?

Answer 4

The severity of infection may depend on the dose of the pathogen experienced by the host

Question 5

What is a propagated epidemic?

Answer 5

Driven by person to person

Multiple waves with progressively taller peaks, where each wave roughly corresponds to the infections caused by the wave preceding it

Question 6

Pathogens evolve (e.g. average viral load) in order to achienve what?

Answer 6

Pathogens evolve (e.g. average viral load) towards a level that balances transmissibility with host survival.

Question 7

What does the persistence of communicable diseases rely on?

Answer 7

Repleishment of susceptible

• Newborns
• Immigration
• Waning of immunity

Question 8

Define

Serial interval

Answer 8

the time between symptom onset of successive cases

Question 9

Define

Herd immunity

Answer 9

a form of immunity that occurs when the vaccination of a significant portion of a population (or herd) provides a measure of protection for individuals who have not developed immunity.

Question 10

Define

Holoendemic

Answer 10

affecting all or characterized by the infection of essentially all the inhabitants of a particular area

Question 11

Define

Epidemic

Answer 11

the occurrence of diseases in excess of what would normally be expected in a community or geographical area

Question 12

What are the possible outcomes of exposure to an infectious agent?

Answer 12

Question 13

Define

Communicable

Answer 13

a disease that can be transmitted from person to person

Question 14

Definition

a disease that can be transmitted from person to person

Answer 14

Communicable

Question 15

Definition

the time between successive infections in a chain of transmissions

Answer 15

Generation time

Question 16

Definition

the proportion of a given exposed population that has been infected by the pathogen

Answer 16

Attack rate

Question 17

What can epidemic curves be used for?

Answer 17

Epidemic size

Case distribution

Point-source exposure or propagated epidemic (serial interval)

Identify impacts of events on disease spread

Question 18

True or False:

Attack rate does not describe how transmissible the pathogen is from person to person

Answer 18

True

Question 19

What is the prevalence formula (usually)?

Answer 19

Total no. of cases at a specific time period / Population size

Question 20

Definition

affecting all or characterized by the infection of essentially all the inhabitants of a particular area

Answer 20

Holoendemic

Question 21

Define

Point-source exposure

Answer 21

Persons are exposed to the same source over a brief time, such as through a single meal or at an event

Question 22

Definition

the time between symptom onset of successive cases

Answer 22

Serial interval

Question 23

What happens if the basic reproductive number is greater than 1?

Answer 23

Ro > 1 The pathogen can lead to an exponentially growing epidemic

Question 24

Shorter generation time or serial interval means what?

Answer 24

Shorter generation time or serial interval means that confirmed and probable cases would need to be identified and removed from population sooner in order to prevent them from spreading the disease

Question 25

# Define Epidemiology

Answer 25

the branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors relating to health

Question 26

# Definition Persons are exposed to the same source over a brief time, such as through a single meal or at an event

Answer 26

Point-source exposure

Question 27

What happens if the basic reproductive number is less than 1?

Answer 27

Ro \< 1 The epidemic will die out without exponential growth

Question 28

# Define Incubation period

Answer 28

the time between infection and symptom onset

Question 29

# Definition an outbreak of global proportions

Answer 29

Pandemic

Question 31

# Define Epidemic curves

Answer 31

a graph that shows the frequency of new cases over time based on the date of onset of disease. The shape of the curve in relation to the incubation period for a particular disease can give clues about the source

Question 32

# Define Reproductive rate

Answer 32

The expected number of secondary cases generated by one infected rate

Question 33

# Define Secondary attack rate

Answer 33

the attack rate of the exposed susceptible population in a semi-closed setting after the introduction of an infected individual into this setting

Question 34

# Define Attack rate

Answer 34

the proportion of a given exposed population that has been infected by the pathogen

Question 35

What type of study are most epidemiological studies?

Answer 35

Observational studies

Question 36

What does the reproductive number describe?

Answer 36

The reproductive number describes the number of people infected by an infected person without giving information on how long it takes for infections to occur

Question 37

# Definition the time taken for a person to become infectious after they have been infected

Answer 37

Latent period

Question 38

What makes up the epidemiological triad?

Answer 38

Pathogen Host Environment

Question 39

The time scale of person-to-person disease transmission, as measured by \_\_\_\_\_\_\_\_\_\_, is an important determinant for the success of quarantine and isolation

Answer 39

The time scale of person-to-person disease transmission, as measured by **serial interval**, is an important determinant for the success of quarantine and isolation

Question 40

What is the prevalence formula for chronic and protracted disease?

Answer 40

Incidence x average disease duration

Question 41

# Define Generation time

Answer 41

the time between successive infections in a chain of transmissions

Question 42

# Definition the time between infection and symptom onset

Answer 42

Incubation period

Question 43

# Definition a form of immunity that occurs when the vaccination of a significant portion of a population (or herd) provides a measure of protection for individuals who have not developed immunity.

Answer 43

Herd immunity

Question 44

# Definition a graph that shows the frequency of new cases over time based on the date of onset of disease. The shape of the curve in relation to the incubation period for a particular disease can give clues about the source

Answer 44

Epidemic curves

Question 45

# Definition the branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors relating to health

Answer 45

Epidemiology

Question 46

# Definition the attack rate of the exposed susceptible population in a semi-closed setting after the introduction of an infected individual into this setting

Answer 46

Secondary attack rate

Question 47

# Define Prevalence

Answer 47

a statistical concept referring to the number of cases of a disease that are present in a particular population at a given time

Question 48

# Define Latent period

Answer 48

the time taken for a person to become infectious after they have been infected

Question 49

# Definition a statistical concept referring to the number of cases of a disease that are present in a particular population at a given time

Answer 49

Prevalence

Question 50

# Define Endemic

Answer 50

the predictable rate of infection in a particular area that is considered "normal"

Question 51

# Define Basic reproductive number (Ro)

Answer 51

a number that represents when the population is completel susceptible. It indicates whether the invasion of the pathogen can give rise to an exponentially growing epidemic

Question 52

# Definition The expected number of secondary cases generated by one infected rate

Answer 52

Reproductive rate

Question 53

How is knowledge of the incubation period used in public health control?

Answer 53

To determine the quarantine duration for suspected cases and contacts of confirmed cases To interpret public health surveillance data

Question 54

What is the time interval between the peaks of successive waves of a propagated epidemic called?

Answer 54

Serial interval

Question 55

# Define Pandemic

Answer 55

an outbreak of global proportions

Question 56

# Definition the predictable rate of infection in a particular area that is considered "normal"

Answer 56

Endemic

Question 57

Over the course of an epidemic, what happens to the attack rate?

Answer 57

The attack rate increases as more people get infected

Question 58

How do you calculate attack rate?

Answer 58

Cumulative no. of infections / Size of exposed population