The chain of infection

The chain of infection refers to the way in which germs spread (Figure1.1). All the steps in the chain need to occur for germs to spread from one person to another. By breaking the chain you can prevent and control infections. The chain can be broken at any stage (Based on material provided by the Australian National Health and Medical research Council).


Figure1.1The chain of infection

The three steps in the chain of infection

1. the germ has a source.

2. the germ spreads from the source.

3. the germ infects another person.

You can break the chain of infection at any stage.

1. The germ has a source

People can pick up germs directly from an infected person, or from the environment. A person with an infection may or may not show any signs of illness. They may be infectious before they become unwell, during their illness or after they have recovered (Source: Australian National Health and Medical Research Council).

For example, in cases of gastroenteritis, children, and staff who no longer have diarrhoea (runny poos) may still have the germs that cause the illness in their poos for sometime. This means that they can still spread the gastroenteritis germ (Based on material provided by the Australian National Health and Medical Research Council).

2. The germ spreads from the source

Germs can spread in a number of ways, including through the air by droplets (sneezing), through contact with poos and then contact with mouths, through direct contact with skin, and through contact with other body secretions (urine, saliva, discharges or blood) (Based on material provided by the Australian National Health and Medical Research Council).

Some germs can spread directly from person to person, others can spread from the infected person to the environment. Many germs can survive on hands, and on objects such as toys, door handles and bench tops. The length of time a germ can survive on a surface (including the skin) depends on the germ itself, the type of surface it has contaminated and how often the surface is cleaned. Washing hands and surfaces regularly with detergent and water is a very effective way of removing germs and preventing them spreading through the environment (Source: Australian National Health and Medical Research Council).

3. The germ infects another person

When the germ has reached the next person it may enter the body through the mouth, respiratory tract, eyes, genitals, or broken or grazed skin. Whether a person becomes ill after the germ has entered the body depends on both the germ and the person’s immunity.

Illness can be prevented at this stage by stopping the germ from entering the body, for example; by making sure that all toys that children put in their mouths are clean, by washing children’s hands and by covering wounds, and by having immunisation against the particular germ (Based on material provided by the Australian National Health and Medical Research Council).

Click here to read about the ways germs can spread in early child care centres.

Ways to break the chain of infection

The most important ways to break the chain of infection and stop the spread of diseases are:

  • effective hand hygiene
  • exclusion of ill children and staff
  • immunisation

other strategies to prevent infection include:

  • coughing and sneezing safely
  • using  gloves correctly
  • good cleaning processes 
  • personal hygiene

(Based on material provided by the Australian National Health and Medical Research Council)

Coughing and sneezing safely

Many germs can be spread through the air by droplets. By covering your mouth and nose when you cough or sneeze, you reduce how far the droplets can travel and stop them from contaminating other surfaces.  In the past, people were encouraged to cover their coughs and sneezes with their hands but if you do not clean your hands immediately, germs stay on your hands and can be transferred to other surfaces (Based on material provided by the Australian National Health and Medical Research Council).

Last updated 6 November 2014.