Epi Class 10

Question 1

Modes of Transmission

Answer 1

Direct (person-to-person) transmission

 - Contact with blood or body fluids
 - Sexual contact
 - IDU (injecting drug use)
 - Fecal-oral spread

Indirect transmission

 - Airborne
 - Vector-borne
 - Vehicle-borne

Vertical transmission
- MTC

Question 2

Reservoir

Answer 2

Where in the ‘environment’ is the infection found?

Examples:

 - Soil
 - Water
 - Humans (anthroponosis)
 - Animals (zoonosis)

Question 3

Cycle of Infection: examples

Answer 3

Human – human – human

Vertebrate – vertebrate – human

Insect - human – insect – human

Complex cycles

Question 4

Infection

Answer 4

agent reproduces inside a person

Question 5

Infectivity

Answer 5

infected / # exposed (and susceptible at time of exposure)

Question 6

Do all exposure cause infection/disease?

Answer 6

Not all exposures cause an infection

Not all infections cause disease (symptoms)

Question 7

Pathogenicity

Answer 7

ill (symptomatic = diseased) / # infected

Question 8

Virulence

Answer 8

with severe illness or death / # with symptoms

High virulence will be associated with a high case fatality rate

Question 9

Acute

Answer 9

short-term (measure with incidence)

Question 10

Chronic

Answer 10

long-term (measure with prevalence)

Question 11

Endemic

Answer 11

always present

Question 12

Epidemic

Answer 12

more cases than normal

Question 13

Pandemic

Answer 13

global epidemic

Question 14

Surveillance

Answer 14

ongoing tracking through disease reports to catch outbreaks early

Question 15

Disease Control

Answer 15

limit infection within an area

Question 16

Elimination

Answer 16

no new cases of the infection in the area

Question 17

Eradication

Answer 17

no new cases anywhere in the world

Question 18

Extinction

Answer 18

not even stored samples in some refrigerator!

Question 19

Epidemiologic Investigation

Answer 19

1. What is the case definition? (How will you know if someone has the disease of interest?)
2. Descriptive Epidemiology Triad:
   
   • Person: Who participated in the study or event?
   • Place: WHERE did the study or event occur?
   • Time: WHEN did the study or event occur?
3. Analytic Epidemiology Triad: Agent – Host – Environment (AHE)
   
   • WHY did the disease outcome occur in certain people or certain population groups?

Question 20

Epidemic Curve: Point Source

Answer 20

One time exposure. Incidence dramatically peak at one point in time

Question 21

Epidemic Curve: Continuous Source

Answer 21

Constant exposure. Incidence remains relatively consistent over time

Question 22

Epidemic Curve: Person-to-Person

Answer 22

Waves of increasing size over time as people spread infection to larger and larger groups.

Person-to-Person epidemic curves can die out naturally if the whole population has been exposed/infected.