Investigating transmission of a disease during an epidemic

Question 1

Transmission definition

Answer 1

The way a pathogen spreads disease from one host to another

Question 2

What are the 3 elements for a chain of infection to be present?

Answer 2

1. Susceptible host
2. Pathogen that is capable of causing the disease
3. Mode of transmission: a way for pathogen to move from host to host

Question 3

Modes of transmission: Direct contact

Answer 3

Transfer of pathogen via exposure to infected skin or bodily secretion
e.g. touching, sexual contact, biting
e.g. HIV/AIDS

Question 4

Modes of transmission: Indirect contact

Answer 4

Transfer of the pathogen to a new host via a moving object
* infection occurs from a reservoir created by the host outside itself, e.g. contaminated materials, airborne transmission and touching infected surface.

e.g. Influenza –> exposure to droplets/ biological matter containing virus

Question 5

Modes of transmission: Vector transmission

Answer 5

Transfer of pathogens via another organism
* a bite from an arthropod that is blood sucking

e.g. Malaria –> transmitted by female anopheles mosquitoes

Question 6

What is an epidemic?

Answer 6

The rapid increase in the occurrence of a particular disease within the population of a defined area

• occurs when conditions are favourable to the pathogen and its mode of transmission

Question 7

What are the different ways in which an epidemic can occur?

Answer 7

1. Pandemic: spreads to many countries around the world
2. Endemic: always present in a particular part of the world
3. Sporadic: occurs in different places at different times with no known connection between outbreaks

Question 8

What makes an epidemic more likely to occur?

Answer 8

1. Little to no immunity in a population and lower state of resistance (malnutrition)
2. A pathogen involved in a virulent strain
3. An easy mode of transmission