Tuberculosis : A major human killer

Tuberculosis (TB) is a bacterial infection spread through inhaling tiny droplets from the coughs or sneezes of an infected person. It is a serious condition, but can be cured with proper treatment. TB mainly affects the lungs. However, it can affect any part of the body, including the glands, bones, and nervous system. Typical symptoms of TB include:

• Apersistent cough that lasts more than three weeks and usually brings up phlegm, which may be bloody
• Weight loss
• Night sweats
• High temperature (fever)
• Tiredness and fatigue
• Loss of appetite
• New swellings that haven't gone away after a few weeks

TB is caused by a bacterium called Mycobacterium tuberculosis. TB that affects the lungs is the most contagious type, but it usually only spreads after prolonged exposure to someone with the illness. For example, it often spreads within a family who live in the same house. In most healthy people the immune system (the body's natural defense against infection and illness) kills the bacteria and you have no symptoms. Sometimes the immune system cannot kill the bacteria, but manages to prevent it spreading in the body. This means you will not have any symptoms, but the bacteria will remain in your body. This is known as latent TB.  If the immune system fails to kill or contain the infection, it can spread within the lungs or other parts of the body and symptoms will develop within a few weeks or months. 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.

Before antibiotics were introduced, TB was a major health problem in the UK. Nowadays the condition is much less common. However, in the last 20 years TB cases have gradually increased, particularly among ethnic minority communities who are originally from places where TB is more common. In 2013 around 8,000 cases of TB were reported in the UK. Of these, more than 5,000 affected people who were born outside the UK. It's estimated around one-third of the world's population is infected with latent TB. Of these, up to 10% will become active at some point.

TB can usually be cured with treatment. Most people need a course of antibiotics, usually for six months. Several different antibiotics are used. This is because some forms of TB are resistant to certain antibiotics. If some one is infected with a drug-resistant form of TB, treatment can last as long as two years.

The BCG vaccine can provide effective protection against TB in up to 8 out of 10 people who are given it. Currently, BCG vaccinations are only recommended for groups of people who are at a higher risk of developing TB. This includes children living in areas with high rates of TB, or those who have close family members from countries with high TB rates, and people under the age of 16 who are going to live and work with local people in an area with high rates of TB for more than three months. Some people, such as healthcare workers, are also vaccinated because of the increased risk of contracting TB while working.

Some countries in different parts of the world have high rates of TB include:

• Africa – particularly sub-Saharan Africa (all the African countries south of the Sahara desert) and west Africa
• southeast Asia – including India, Pakistan, Indonesia and Bangladesh
• Russia
• China
• South America
• Western Pacific region (to the west of the Pacific Ocean) – including Vietnam and Cambodia