Tuberculosis (TB) is a bacterial infection. It is spread through inhaling tiny droplets of saliva from the coughs or sneezes of an infected person.
TB mainly affects the lungs. However, the infection can spread to many parts of the body, including the bones and nervous system.
Typical symptoms of TB include:
- a persistent cough
- weight loss
- night sweats
See Tuberculosis - symptoms for more information.
The bacteria responsible for TB are very slow moving, so TB develops slowly in the body. You may not experience any symptoms for many months or even years after being infected.
What happens if you are infected?
Three things can happen if you are infected with TB:
- Your immune system (the body’s natural defence against infection and illness) kills the bacteria and you have no further symptoms. This happens in most cases.
- Your immune system cannot kill the bacteria, but manages to build a defensive barrier around the infection. This means that you will not have any symptoms, but the bacteria will remain in your body. This is known as latent TB.
- Your immune system fails to kill or contain the infection and it slowly spreads to your lungs. This is known as active TB.
Latent TB could develop into an active TB infection at a later date, particularly if your immune system becomes weakened.
Outlook
If it is not treated, an active TB infection can be fatal. It can damage the lungs to such an extent that a person cannot breathe properly.
With treatment, a TB infection can usually be cured. Most people will need to take a long-term course of antibiotics, which usually lasts for at least six months. See Tuberculosis - treatment for more information.
However, TB can sometimes be fatal even with treatment.
Vaccination
The Bacillus Calmette-Guérin vaccine, also known as the BCG vaccine, can protect against TB. The BCG vaccine provides effective protection against TB in up to 8 out of 10 of people who are given it.
BCG vaccinations are not routinely given as part of the childhood vaccination schedule, unless a baby is thought to have a higher than normal risk of coming into contact with TB.
For example, babies born in areas of inner-city London, where TB rates are higher than in the rest of the country, will probably be given the BCG vaccination.
Vaccinations may also be recommended for people who have an increased risk of developing a TB infection. This includes health workers who may be exposed to TB and children who have recently arrived in the UK from countries that have high levels of TB.
See Tuberculosis - prevention for more information about the BCG vaccination.
How common is TB?
Before antibiotics were introduced, TB was a major health problem in England. Nowadays, the condition is much less common. However, in the last 20 years TB cases have gradually increased, particularly among ethnic minority communities originally from places where TB is widespread.
In 2009, 9,040 cases of TB were reported in the UK. Most of these occurred in urban centres, with over one-third of cases in London. Globally, TB remains a major public health problem. There were 9.4 million new cases of TB in 2009, and 1.7 million deaths from the condition.
Countries with high numbers of HIV cases also often have high numbers of TB cases. This is because HIV weakens a person’s immune system, which means they are more likely to develop a TB infection.
It is also estimated that one-third of the world’s population is infected with latent TB. Up to 1 in 10 of people with a latent TB infection (but who do not have HIV) will develop active TB at some point.
