Outbreak --exam 2

Question 1

What are 3 elements involved in the Epidemiologic triad?

Answer 1

1. Host
2. Agent
3. Environment

Question 2

what % of human pathogens are zoonotic?

Answer 2

60%

Question 3

What are 2 main modes of transmission?

Answer 3

1. Horizontal

2. Vertical

Question 4

What are 2 types of Horizontal transmission?

Answer 4

1. Direct = contact with host or host’s discharges
2. Indirect =include intermediate vehicle
   
   • Vector
   • Inanimate objects = fomites

Question 5

What is the most dangerous time for Dz transmission?

Answer 5

Between beginning of infectious period (shedding agent) and symptomatic period (showing clinical signs)

Question 6

What is Isolation?

Answer 6

Separation of CASES (Dz’ed animals) from susceptible individuals during the period of communicability

Question 7

What is quarantine?

Answer 7

Separation of HEALTHY INDIVIDUALS following contact with cases, usually for a minimum of 1 incubation period

Question 8

What can you do to control dz?

Answer 8

1. isolation/quarantine
2. Tx to prevent shedding
3. disinfect environment
4. decrease vector/fomite

Question 9

What is Herd Immunity?

Answer 9

Proportion of resistant individuals –> resistance of a group to invasion and spread of an infectious agent

• • By vx a large proportion (Mass immunization) –> altered dynamics of dz transmission
• • WHO recommends 70-80% vax

Question 10

What is an outbreak?

Answer 10

AKA Epidemic
- an increase in the incidence of disease above normal

• confined by a given population, time, and place

Question 11

Sporadic

Answer 11

• Rare and irregular case(s)

- not predictable

Question 12

Endemic

Answer 12

• Stable state

- predictable

Question 13

Epidemic

Answer 13

In excess of the expected level (i.e. endemic)

Question 14

Pandemic

Answer 14

Widespread epidemic affecting a large proportion of population, often many countries

Question 15

Steps in outbreak Investigation

Answer 15

1. Confirm that there is an outbreak
2. Formulate case definition
3. Isolate and survey known cases
4. Characterize the outbreak in space and time
5. Formulate/test/revise/retest hypothesis
6. Implementation of control measures
7. Disseminate results

Question 16

What is an epidemic curve?

Answer 16

Number of new cases (y-axis)
vs Time (x-axis)

Question 17

2 potential patterns of outbreaks

Answer 17

1. Common source
   
   • point source
   • continuous
2. Propagation

Question 18

What can epidemic curves tell us?

Answer 18

1. pattern of spread
2. Magnitude of outbreak
3. Time trends of outbreaks

Question 19

What is the benefits of using Line listing charts?

Question 20

What is attack rate?

Answer 20

sick / total

Attack rate ratio: AR(exposed)/ AR(unexposed)