Surveillance

Question 1

What is the difference between sampling and a census survey?

Answer 1

Sampling = some animals in a population are chosen to be examined
Census = all animals in a population are tested.

Question 2

What are two examples of passive surveillance?

Answer 2

Abattoir meat inspection

Disease reporting by farmers.

Question 3

Define general surveillance.

Answer 3

Focused on detecting any disease or pathogen. e.g. foal abortions and caterpillars case.

Question 4

What is general surveillance used for?

Answer 4

Detecting new or unknown diseases. Will require a follow-up test to determine the exact disease.

Question 5

Define representative surveillance.

Answer 5

Collect a representative sample from a population

Question 6

What is a representative surveillance used for?

Answer 6

Estimate the prevalence of the disease.

Question 7

Define targeted surveillance

Answer 7

Focusing on high risk groups based on epidemiological risk factors. i.e BSE risk factors = neurological disorder displayed and fed meat in diet. Therefore would test these animals.

Question 8

What is the purpose of using a targeted surveillance.

Answer 8

For disease detection, especially if you want to prove a country’s freedom from a disease.

Question 9

Define risk-based surveillance.

Answer 9

A focused surveillance of an affected area and places at higher risk/close proximity to the affected areas. Prior epidemiological knowledge of the disease is required.

Question 10

What is the purpose of using a risk-basked surveillance.

Answer 10

To know where it is best to focus resources based on probability of occurrence and consequences if event occurs. Also good to demonstrate freedom from disease.

Question 11

What type of surveillance is farmer reporting system?

Answer 11

Passive general

Question 12

What type of surveillance is Abattoir surveillance system?

Answer 12

Passive

Sometimes active if you are doing a specific survey for a sample.

Question 13

What type of surveillance is using Sentinel herds?

Answer 13

Active surveillance of a small group of susceptible animals to a disease. Tested regularly to warn if the disease is present.

Question 14

What are 3 models that we use for disease control?

Answer 14

Causal model - HAE causal triangle.
Component cause model - what 'pieces of the pie' are required for the disease to be present.
SEIR model (for infectious) - susceptible* --> exposed --> infectious* --> recovered).

Question 15

What are 4 mechanisms to control or eradicate a disease?

Answer 15

1. Reduce susceptible
2. Reduce contact/transmission
3. Improve immune defence
4. Improve environment (better for host and more hostile for agent).

Question 16

What are some control methods that reduce transmission?

Answer 16

Quarantine, slaughter, movement control, control, fomite disinfection vectors/intermediate hosts, grazing strategies, move susceptible, better husbandry and nutrition

Question 17

What are some control methods to reduce susceptible

Answer 17

Vaccination, therapeutic and prophylactic drugs, genetic improvement, better husbandry and nutrition.

Question 18

What are some reasons why an outbreak may occur despite Vx?

Answer 18

Environment - stress inducing
Host - health and nutritional status
Agent - mutate
Vaccine - made ineffective.

Question 19

What are 5 reasons why we want to investigate an outbreak?

Answer 19

1. Stop it
2. Prevent repeat
3. Evaluate existing control
4. Address public concerns
5. Training (stimulations)