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Wirral University Hospital NHS Foundation Trust

How is TB contracted

People get TB when they breathe in the TB bacteria, which are spread through the air. But most people won’t get ill because:

  • TB bacteria are only in the air after someone with infectious TB coughs or sneezes.
  • You need to spend many hours close to a person with infectious TB to breathe in enough bacteria to be at risk.
  • Most people's immune systems are strong enough to kill off TB bacteria.

You can not get TB by:

  • Shaking someone's hand
  • Sharing food or drink
  • Touching bed linens or toilet seats
  • Sharing toothbrushes
  • Kissing

There are two kinds of tests that are used to determine if a person has been infected with TB bacteria: the tuberculin skin test (Mantoux) and TB blood tests (T-Spot).

A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB or active TB. Other tests, such as a chest x-ray and a sample of sputum, are needed to see whether the person has TB.