How diseases spread.ppt

Infectious diseases transmission

1. HOW INFECTIONS
SPREAD
1

2. Transmission of Infectious
Agents
Reservoir
•Any person, animal, soil or substance
in which an infectious agent normally
lives and multiplies
•Can be symptomatic, but usually
asymptomatic

3. Animal Reservoirs

4. Transmission of Infectious
Agents
Carrier
•A person who is a carrier of the
microorganism that may never
develop the disease and is able to
pass the microorganism to other
people

5. Links in the Infection Chain
Agent: the microbe
causing the infection

6. Portal of exit –how agent leaves
reservoir

7. Portal of entry: access to new host
Susceptible host: a member of a
population who is at risk of becoming
infected by disease; depends on:
Health status
Immunity
Age
Nutrition

8. Mode of transmission
Method whereby the agent
reaches a new susceptible
host

9. Modes of Transmission
Direct contact
No intermediary
Direct contact with
infected blood or bodily
secretions
EX: Touching infectious
lesion, sexual activity

10. Modes of Transmission
Indirect contact
Involves intermediary object
or organism
Contaminated hand or food
Fomite—inanimate objects or
materials that are likely to carry
infection

11. Droplet transmission
Respiratory or salivary
secretions are expelled from
infected individual
Aerosol transmission
Involve small particles from
the respiratory tract
suspended in air and can
travel farther than droplets

12. Vector-borne
Insect or animal is an
intermediate host
Vector
an organism does not cause
disease itself spreads infection by
passing the pathogen from one
host to another; usually part of
the lifecycle of the pathogen

13. Vectors