Tuberculosis - Prevention and prognosis

Authored by Dr Laurence Knott, 05 Jul 2017

Reviewed by:
Dr Adrian Bonsall, 05 Jul 2017

If you have active tuberculosis (TB) in the lung, you can infect other people until you have taken the correct treatment for two weeks. After that, normally you will not be infectious (but you should continue with the treatment). During the first two weeks of treatment, you will be advised to stay at home (or stay in your room if in hospital) and avoid contact with anyone who has poor body defences (immune system). For example, people with HIV, those taking chemotherapy medicines, or young babies.

Sometimes extra precautions are needed - for example, if your TB is thought to be very infectious or resistant (see 'Special circumstances', below).

Household members and close regular contacts of a person with TB of the lungs (pulmonary TB) or voice box (laryngeal TB) may be advised to have tests. Close regular contacts may include colleagues, friends, classmates, teachers and non-teaching school staff, depending on the situation and on how infectious your TB is. The usual tests for contacts are a chest X-ray and/or a tuberculin test (Mantoux test). If these show possible TB then further tests can be done to look for active TB.

Special rules apply for babies and young children aged less than 2 years who have been in contact with active TB. Diagnosing TB in young children is difficult. In the early stages, the infection may not show up on tests. But young children are vulnerable to TB (they can get a severe infection). Therefore, they may be started on some treatment (such as isoniazid) for several weeks. This helps to prevent a severe infection whilst having further tests to see if TB is present.

With treatment, most people make a full recovery. If left untreated, about half of people with active TB eventually die of the infection. TB bacteria) multiply quite slowly compared to most other bacteria. Therefore, active TB tends to cause an illness that slowly gets worse. Some people survive without treatment and may even fully recover. The outlook (prognosis) tends to be worse where the TB is more difficult to treat. For example, with HIV/AIDS, other serious illness, or extensively drug-resistant TB.

TB is both preventable and treatable. It is a tragedy that it remains one of the biggest killers worldwide. Relieving poverty, better nutrition and prompt treatment of TB are the most important ways of reducing TB worldwide. Immunisation also helps.

Immunisation against tuberculosis (the BCG vaccine)

See separate leaflet called BCG Immunisation for more details.

A 'screening test' for TB means testing someone who is well, with no symptoms, for TB. The tests used for screening are a chest X-ray and/or a tuberculin test. Sometimes an interferon gamma blood test is used as well. In the UK, screening is currently recommended for:

  • Close contacts of people with active TB (as above).
  • People newly arrived in the UK from countries with high rates of TB.
  • People at risk due to their job - for example, healthcare workers, prison staff, etc.
  • Homeless people living on the street or in hostels.

Further reading and references

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