Question

The chain of infection explains how infection is transmitted from one person to another. Build on the following diagram using your understanding of the chain of infection (the 6 elements) and define each element below giving at least one example of each element.

Answer 1

The six elements in the chain of infection are

1)Infectious agent

2)Reservoir

3)Portal of exit

4)Mode of transmission

5)Portal of entry

6)Susceptible host

Infectious agent means the pathogen that cause disease

Eg:-bacteria ,virus, fungus, parasites

Reservoir is the place that harbour the infectious agent

Eg:- human beings, animals, insects, soil,water etc

Portal of exit is the way through which the pathogen leaves the reservoir

Eg:- coughing, sneezing , open wounds etc

Mode of transmission is the means through which the pathogen is passed on to the host

Eg:- direct contact, ingestion,inhalation etc

Portal of entry is the way through which pathogen enter the host

Eg:- through breaks in skin, respiratory tract, mucus membranes etc

Susceptible host can be any human being.Those who are immunocompromised , extremes of age, underlying diseases are more susceptible to infection

Example

For the infectious agent Influenza virus, reservoir is humans, portal of exit is respiratory droplets,mode of transmission is by inhalation or direct contact,portal of entry is the respiratory tract, susceptible host is humans.

The chain of infection can be broken at these six levels in order to stop the spread of infection.

Breaking the chain can be done at various levels by

1)Immunisation and treatment of diseases in the susceptible host

2)Early diagnosis and treatment of the pathogen

3)Cleaning, disinfection, infection control policies at the level of reservoir

4)Hand hygiene, personal protective equipments , respiratory etiquette etc - at the level of portal of exit, mode of transmission and portal of entry