How infectious diseases spread

Infectious diseases are caused by organisms such as bacteria, viruses, fungi or parasites.

By understanding about how people can catch an infectious diseases, you can then take effective action to preventing their spread.

Ways people spread infectious diseases

Infectious diseases have different ways of spreading from person to person. They can be spread in three main ways: through the air, through direct contact between people, and/ or contaminated objects or surfaces.

Through the air

Droplets containing small particles of a disease, such as measles, chickenpox and influenza (the flu), can be present in the air when an infected person coughs or sneezes. Breathing in these infectious particles is how you get sick.

Through direct contact

Touching an infected animal, person or their bodily fluids and not washing your hands, increases your risk of giving yourself and others the infection. Possible bodily fluids are saliva, blood, sweat, urine (wee) or faeces (poo). Examples of infectious diseases include norovirus and Hepatitis B.

Through contact with contaminated surfaces or objects

Touching a surface or object that has been contaminated by an infected person’s disease particles and not washing your hands, increases the risk of giving yourself or others the disease. Examples of infectious diseases include influenza (particles of virus from a sneeze) and norovirus.

Common infectious diseases

Not all infectious diseases are spread in the same way, and some are more infectious than others.

An information sheet on common infectious diseases, how they are spread and signs and symptoms is available on the HealthEd website.

Contaminated food or water

Some diseases can also be spread through contaminated food or water. Find out more about common foodborne illnesses on the Ministry for Primary Industries website.

Read more information about these food-related diseases:

There's more information and factsheets on common viruses and infections, their symptoms and prevention, in the A to Z of Diseases and illnesses.

What you can do

Learn about simple actions you can take to reduce the risk of spreading a disease: Prevent the spread of infectious disease

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