Causes of flu (influenza)

Learn about the causes of flu and how it is spread.

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What causes flu?

The flu is an infection of the nose, throat and lungs. It is caused mainly by 2 types of viruses:

  1. influenza A
  2. influenza B

How is flu spread?

The flu spreads very easily from person to person. Even before you notice symptoms, you may spread the virus to others. If you have the virus, you can spread it to others by:

  • sneezing
  • coughing
  • talking

These actions release tiny droplets containing the flu virus into the air.

You can become infected if these droplets land on your:

  • nose
  • mouth
  • eyes

Infection can also happen if you touch any of these body parts after touching objects contaminated by infected droplets. Common contaminated objects include:

  • doorknobs
  • phones
  • television remotes
  • someone's hands
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