L26: Outbreak, Infectious Disease

Question 1

Epidemic and outbreaks, Pandemics, Endemic

Answer 1

Epidemic: Occurrence of health related events (disease) in excess of normal expectancy in regional level

Outbreak: institutional level

Pandemic: Multiple countries and continents

Endemic: Maintained within a population / certain area without need for external introduction

Question 2

Epidemiology

Answer 2

Study of disease-

1. Distribution
   - Who
   - How many
   - Where
   - When
2. Determinants
   - How
   - Why

Question 3

Koch’s postulates (4 points)

Answer 3

1. Organism demonstrable in diseased patients but not in healthy individuals
2. Isolated in pure culture
3. Inoculation should reproduce disease in susceptible animals
4. Organism can be re-isolated from infected animals

Question 4

Limitations of Koch’s postulate

Answer 4

1. Not all pathogens can be cultured
2. Asymptomatic carrier
3. No experimental animal models for all disease

Question 5

Fredricks and Relman criteria (5 points)

Answer 5

1. Nucleic acid sequence of pathogen present in gross anatomical site but not in unaffected organs
2. None or few copies of pathogen’s nucleic sequence in healthy individual
3. Sequence copy number correlates / in proportion to disease severity
4. Organism inferred consistent with biological characteristics of that group
5. Evidences should be reproducible

Question 6

Bradford-Hill criteria (9 points)

Answer 6

Find out how likely a thing is the cause of a disease

1. Strength of association between agent and disease: no. of diseased people vs agent
2. Consistency
3. Specificity: agent is limited to only diseased people
4. Temporality
5. Biological gradient: dose-dependent
6. Plausibility: possible mechanism
7. Coherence: same microorganism detected in various case
8. Experiment: response to intervention
9. Analogy: any related pathogens

Question 7

Epidemiological triangle

Answer 7

1. Host
2. Agent
3. Environment / Vector

Question 8

Definition of ”One Health”

Answer 8

Collaborative efforts of multiple disciplines to attain optimal health for HUMAN, ANIMAL and ENVIRONMENT

Question 9

2 types of epidemic curve

Answer 9

1. Point-source epidemic

2. Propagated epidemic (person-to-person)

Question 10

What is disease surveillance?

Answer 10

Ongoing, systematic collection, analysis and interpretation of data to

• Plan
• Execute
• Evaluate

Collection of data:
Active: Special investigations, Serologic surveys
Passive: Registries, Notification, Lab specimens

Question 11

Iceberg concept of disease

Answer 11

1. Iceberg = Clinically visible disease state

2. Underlying = Subclinical situation which outweigh clinical situation and can cause potential hazards