Tuberculosis

What is tuberculosis?

Tuberculosis (TB) is an infection caused by a bacterium (germ) called Mycobacterium tuberculosis. TB usually affects the lungs, but any part of the body can be affected.

How does tuberculosis infection occur?

Most cases affect the lungs at first. TB bacteria are coughed or sneezed into the air by people with active TB disease. The bacteria are carried in the air in tiny water droplets. If you breathe in some TB bacteria, they may multiply in your lung. There are then three ways the infection may progress.

1. Minor infection with no symptoms - occurs in most cases

2. Infection progressing into active TB disease - occurs in some cases

Active TB disease with symptoms occurs in some people who breathe in some TB bacteria. In these people the immune system does not win the battle and halt the invading bacteria. The TB bacteria multiply further and spread to other parts of the lung and body. Symptoms of active TB then develop about 6-8 weeks after first breathing in some bacteria.

TB infection which progresses to active disease can occur in anybody who is infected with TB bacteria. However, it is more likely if you are already in poor health. For example, it is common in malnourished children in developing countries. Newborn babies are also more at risk of active TB.

3. Re-activated (secondary) infection causing active disease

Some people develop active TB months or years after a minor TB infection had been halted. The body's immune system at first stops the bacteria from multiplying (as above). However, not all the bacteria may be killed. Some bacteria may be 'walled off' in the scar tissue of the initial minor infection. They are stopped from multiplying by the immune system. They do no harm but can remain dormant (inactive) for many years. Dormant TB bacteria may start to multiply and cause active TB if the body's immune system becomes weaker for some reason. A weak immune system and re-activated TB is more likely to occur if you:

• are elderly or frail
• are malnourished
• have diabetes
• take steroids or immunosuppressant medication
• have kidney failure
• are alcohol dependent ('alcoholic')
• have AIDS

How infectious is tuberculosis?

A person with active TB disease in the lungs, will cough and sneeze TB bacteria into the air, which can infect others. To catch TB you normally need close and prolonged contact with a person who has active TB in the lungs. So, the people most likely to be infected will be those in the same house or same family. In the UK, if someone is diagnosed with tuberculosis, then health workers will arrange TB tests for their close contacts (more details below).

How common is tuberculosis?

TB is common in developing countries and parts of Eastern Europe. It causes more deaths worldwide than any other infectious disease (about three million per year). The main factors contributing to TB in the developing world are: poor nutrition, poor housing, poor general health, insufficient healthcare and AIDS (TB is common in people with AIDS).

In the UK, active TB was common in the nineteenth century (the old 'consumption'). Better living conditions, better nutrition, immunisation and effective treatments in the twentieth century all combined to make TB uncommon.

The number of people with active TB was at an all time low in the UK in the early 1980s. Since then the number of cases has increased. This is probably due to a combination of factors. These include: an increase in poverty, the ageing population, immigration from areas where TB is common, more people travelling to areas in the world where TB is common, and AIDS.

Currently in the UK, about 8,500 new cases of TB are diagnosed per year (about 1 in 7,000 people). Rates of TB vary in different parts of the UK, with some London boroughs having very high rates.

Who gets tuberculosis?

Anyone can get TB. The risk is increased where one or more of the following apply:

• Close contacts of a person who has active TB in the lungs (living in the same household, or spending a lot of time with that person).
• If you or your family come from a country where TB is common.
• Environment and poverty: rates of TB are higher among homeless people, prisoners, in large cities and in more deprived areas.
• A poor immune system, for example, due to HIV infection, immune-suppressing treatment, alcohol or drug addiction.
• Malnutrition: poor nutrition and lack of vitamin D are linked to TB.
• Age: babies, young children and the elderly are more susceptible to TB.

What are the symptoms of active tuberculosis?

Cough lasting more than three weeks is often a first symptom. It can start as a dry irritating cough. It tends to continue for months and get worse. In time the cough usually becomes 'productive' and you tend to cough up a lot of sputum (phlegm), which may be bloodstained.

Other common symptoms are: fever, sweats, feeling unwell, weight loss, pains in the chest, and poor appetite. You may become breathless if the infection progresses and damages the lungs. If left untreated, complications often develop, such as fluid collecting between the lung and the chest wall (pleural effusion). This can make you very breathless. If the TB gets close to a blood vessel in the lung, then you may cough up blood.

TB infection sometimes spreads in the bloodstream and lymphatic system to cause infection in other parts of the body. Depending on which part of the body is affected, various symptoms may then occur:

• Lymph glands - you may have a swollen gland or glands anywhere in the body. If the swollen glands are in the neck, armpit or groin then you may see or feel them.
• Gut and abdomen - the TB may cause tummy pain or swelling, or poor digestion of food with diarrhoea and weight loss.
• Bones and joints - TB can get into a bone or joint, causing bone pain (for example, in the spine) or pain and swelling in a joint.
• Heart - TB sometimes causes inflammation around the heart, with chest pain or shortness of breath.
• Kidneys and bladder - if these are infected, you may have pain in the loin (side), or pain when passing urine.
• Brain - TB can cause meningitis, with symptoms such as headache, nausea and vomiting, convulsions, drowsiness or behaviour change.
• Skin - TB can cause certain rashes, including ‘erythema nodosum’ which is a red, lumpy rash on the legs, or ‘lupus vulgaris’ which gives lumps or ulcers.
• Spread to many parts of the body – this is called ‘miliary TB’, and can affect many organs including lungs, bones, liver and eyes and skin.

How is TB diagnosed?

Diagnosing TB is sometimes straightforward, but the diagnosis may be more difficult in some situations. In general, the diagnosis is made by looking at the ‘clinical picture’ (which is your symptoms and a doctor’s examination), combined with the results of certain tests. To start with, you will usually have a chest X-ray and/or a tuberculin test, followed by sputum tests.

Chest X-ray

A chest X-ray usually shows any active lung TB. It may also show healed or inactive TB.

Tuberculin skin testing (Mantoux, Heaf or Tine test)

This test shows whether you have been in contact with TB bacteria at some point in your life. However, it cannot prove you have a current active infection. The 'tuberculin' is made from part of the TB bacterium. It is injected into the skin. The injection site is examined a few days later.

A positive reaction is a red inflamed area of the skin. This means that you either have a current infection, or have had a previous infection, or you have been immunised in the past with BCG. (BCG is the vaccine used to prevent TB.) A negative skin reaction tends to rule out TB. However, the result can be falsely negative in some situations. For example, if you have severe TB, if you have AIDS or a poor immune system, or in young children in the early stages of infection.

Sputum tests

If the chest X-ray or tuberculin test results suggest that TB is possible, the next test will be to look for TB bacteria from the lung. This is done by sending samples of sputum (phlegm) to the laboratory.

First, a ‘smear’ of the sputum is examined in a laboratory under a microscope using a special stain (dye) to show the TB bacteria. The results are obtained quite quickly, usually within a few days.

Another test for the sputum samples is a ‘culture’ test. This involves growing (culturing) the TB bacteria in the laboratory. This can take several weeks because TB bacteria grow slowly. There are two important reasons for doing this test. Firstly, to detect TB bacteria that may not be found on the ‘smear’ test. Secondly, the culture test can check whether the TB bacteria are resistant to any antibiotics. (Antibiotic resistance is explained below.)

It can take several weeks for the sputum test results to 'prove' the infection. Therefore, many people with suspected active TB (with typical symptoms and X-ray changes) are started on treatment before the results are back. This is to prevent the disease from getting worse, and to prevent spread to other people.

It is sometimes difficult to get sputum for the test (for example, with children). A sample of fluid from the stomach ('gastric washings') may then be used instead.

Other tests

Other possible tests for suspected TB are:

• A blood test called an ‘interferon-gamma test'. This can be helpful if the tuberculin skin test result was unclear. The advantage of this test is that the result is not affected by the BCG vaccine.
• An HIV test should be offered. This is because TB is more common in people who have HIV, and treatment may be needed for both conditions.
• A CT or MRI scan may be used to look for TB in internal organs. For example, a brain scan is useful if TB meningitis or TB infection in the brain is suspected.
• Samples from other parts of the body. TB may be suspected in organs other than the lung. It may then be helpful take a sample of tissue or fluid from the affected part of the body. This sample can then be tested in the laboratory by the same methods used for sputum samples (above). For example, samples can be taken from urine, lymph glands near the skin, or from the lung. A test called a 'lumbar puncture' samples fluid near the spine, if meningitis is suspected.
• New tests are being developed. Some are similar to the culture test above, but give faster results. Other tests help identify bacteria which are resistant to antibiotics.

What is the treatment for tuberculosis?

'Normal' antibiotics do not kill TB bacteria. You need to take a combination of special antibiotics for several months. Standard treatment in the UK is usually for six months. First, it involves a combination of four antibiotics that you take for two months. These are isoniazid, rifampicin, pyrazinamide, and ethambutol. This is followed by continuing with rifampicin and isoniazid for a further four months. Variations on this treatment plan may be advised, depending on what type of TB you have and which part of the body is affected.

If treatment fails, it is often due to not taking medication properly and regularly. It is vital that you follow the instructions about medication. Even if you feel much better in a few weeks (as many people do), you must finish the full course of treatment.

Attending follow-up appointments is important. This is to check that your TB is responding to the treatment, and to check for any side-effects of treatment.

Why is important to take the full course of treatment?

The TB bacteria in the body are more difficult to get rid of than "ordinary" bacteria. Only a long course of treatment can fully clear TB bacteria from the body. If you do not take the full treatment then the following problems often occur:

• You may remain infectious to other people.
• You may not be cured. You may feel better at first, but some TB bacteria may stay in your body. These can reactivate at a later time and make you very ill.
• If the original infection is only partly treated, the bacteria can become resistant to antibiotics (explained below). The TB then becomes more difficult to treat.

Are there side-effects of TB treatment?

The medicines used to treat TB have a good safety record. Sometimes side-effects occur. If one does, see a doctor urgently, so that your treatment can be adjusted or changed to a different antibiotic.

You can read the leaflet which comes with the medicine packet for a list of possible side-effects. Some important things to know are:

• Liver problems. You will have blood tests to monitor your liver function. It is common to get mildly abnormal liver tests when taking TB treatment. About 1 in 100 people may develop very abnormal tests or liver problems. If that occurs, the treatment needs to be changed. Symptoms of liver problems are: jaundice (yellow tinge to the skin and eyes), fever, nausea, itching or feeling generally more unwell. If you have any of these, stop the tablets and see a doctor urgently.
• Vision changes (if taking ethambutol). Early symptoms are slight loss of vision or loss of colour vision. If you notice any loss of vision, stop the ethambutol and see a doctor urgently. Vision can recover fully if the ethambutol is stopped quickly.
• Neuropathy (if taking isoniazid). This can cause numbness and tingling in the arms and legs. It can be helped by taking an extra vitamin (pyridoxine) - which is sometimes prescribed together with the isoniazid.
• Rifampicin makes your tears and urine orange-coloured. This is normal.
• TB medication can affect other medicines, including the contraceptive pill. Tell the TB clinic about all your medication, so that it can be taken into account when deciding about treatment.

How do I get tests and treatment for TB?

Tests and treatment for tuberculosis are free to everyone in the UK - even if you are not a UK resident.

Your doctor will refer you for tests if he or she suspects that you have TB. This is usually to a local TB or chest clinic. In addition, there are also 'mobile X-ray units' in London, which provide chest X-rays as an initial test for TB. The mobile units visit prisons, shelters for the homeless, and refugee centres. See the further information section (below) for more help with accessing NHS services.

Treatment is normally from a TB clinic. Most hospitals in the UK have a 'chest clinic' or 'TB clinic' with staff experienced in treating TB. Your GP can help with prescriptions.

Most people with TB can have treatment at home. Hospital admission is not usually necessary unless you are quite ill, or the treatment is complicated for some reason, or you have difficult circumstances such as homelessness.

Some people find it hard to remember to take their medication regularly. If so, you may be offered 'observed treatment', where a health worker sees you for each dose. The treatment schedule is adjusted so that medication is taken three times weekly instead of daily.

Are precautions needed to stop others catching the infection?

If you have active 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 a poor immune system. For example, people with HIV, those taking chemotherapy, or young babies.

Sometimes extra precautions are needed. For example, if your TB is thought to be highly infectious or resistant (see special circumstances, below).

Do family, friends or colleagues need tests?

Household members and close regular contacts of a person with active TB may be advised to have tests. (Close regular contacts may include colleagues, friends or classmates, 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. If these show possible TB, then further tests can be done (as above) to look for active TB.

Special rules apply for babies and young children under two 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.

Special circumstances

Drug resistant TB

Some people have TB bacteria which are 'resistant' to certain antibiotics - meaning that the bacteria are not killed by that antibiotic. This means that other antibiotics have to be used instead, to cure the TB. So antibiotic resistance can make the TB more difficult to treat, and more dangerous to others who are infected. Difficulty of treatment is increased if the bacteria are resistant to more than one antibiotic (multidrug resistant TB) or more than three antibiotics (extensively drug resistant TB).

Drug resistant TB can be due to not taking a full course of treatment, or to catching TB with bacteria that are already resistant.

If you have (or may have) drug resistant TB, then extra precautions are needed to prevent the infection spreading to others. Your health worker will advise about this. You will need different antibiotics from the standard treatment above, with advice from a specialist.

TB and HIV infection

TB is more common in people with HIV infection. It may be more difficult to diagnose, because the symptoms and test results may not be typical. Also, treatment can be more complex because the TB medication and the HIV medication can interfere with each other. Specialist advice may be needed.

Sometimes, if you have TB and then start antiviral treatment for HIV, the TB symptoms can get worse for a while. This happens because the immune system gets stronger and produces a reaction to the TB infection.

Steroid treatment

Steroid treatment (prednisolone) is recommended as an additional treatment for some forms of TB. If there is TB in the brain (meningitis), or TB around the heart (pericarditis), then a course of prednisolone can help prevent complications.

What is the outlook (prognosis) if you have active tuberculosis?

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 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.

How can tuberculosis be prevented?

TB is both preventable and treatable. It is a tragedy that it remains one of the biggest killers world-wide. 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)

The BCG (Bacillus Calmette-Guérin) vaccine was introduced into the UK in 1953. Over many years it has been shown to be safe. The vaccine contains a small number of modified TB bacteria. The vaccine stimulates the immune system to be ready to fight TB bacteria. The BCG vaccine is thought to give up to 70% protection against TB. It is more effective for children than for adults. Although it is a good vaccine, it does not guarantee protection against TB. The BCG vaccine is offered to the following people in the UK:

• Babies under one month (neonates) living in areas of the UK where there is a high rate of TB. That is, areas where the incidence of TB is 40 cases per 100,000 people per year, or greater. (Your doctor or midwife will be able to tell you if you live in an area with a high rate of TB.) Also, those whose parents or grandparents have lived in a country with a high rate of TB, or whose families have had TB in the last five years.
• Babies and children (under 16 years), if not already vaccinated, who are considered at increased risk of TB. For example, whose parents or grandparents have lived in a country with a high rate of TB. Children age 6-16 should have a tuberculin test first, and be vaccinated if it is negative.
• Also, BCG is recommended for the following groups of people who have not previously been immunised (if their tuberculin test is negative):
  • People aged under 35 entering the UK, who have lived for at least 3 months in a country with a high rate of TB.
  • People at risk due to their job. For example, healthcare and hospital workers, prison staff and others working in places where there may be high rates of TB.
  • Close contacts of people with active TB.
  • People who intend to live for one month or more in countries with a high TB rate.

Note: Previously, all schoolchildren in the UK were routinely given the BCG vaccine at age 13. The policy changed in 2005, due to the changing patterns of TB in the UK. Rates of the disease are now very low in many parts of the country, and children living in these areas have a very low risk of infection. However, in other areas, rates of TB are increasing, so the BCG vaccine is targeted to these areas. See also separate leaflet called 'BCG Immunisation' for more detail.

Who should have 'screening tests' for TB?

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.

Other TB bacteria

As mentioned above, the disease that we call 'tuberculosis' or 'TB' is caused by a bacterium called Mycobacterium tuberculosis. Other bacteria in the same family are called Mycobacterium bovis and Mycobacterium africanum. They are rare causes of infection in the UK. Mycobacterium bovis used to be more common as it is passed on from contaminated unpasteurised milk, or from infected cattle (now rare in the UK). Treatment for these infections is mostly similar to that for standard TB.

There are various other bacteria in the mycobacterium family which are called atypical mycobacteria. Most of these do not cause infection. However, they sometimes cause serious infection in people whose immune system is not working very well. (For example, some people who have AIDS.) Treatment is with long courses of antibiotics.

Further help and information

TB Alert

22 Tiverton Road, London NW10 3HL
Web: www.tbalert.org

• Aims to increase awareness of TB in the UK and worldwide. Aims to raise funds to support work against TB in the countries most affected.
• Can supply patient information leaflets in many languages.
• Has a hardship fund providing grants to people in need who have TB, to help with costs such as prescriptions, travel, meals etc.

Project: London

Praxis, Pott Street, London E2 0EF
Tel: 020 8123 6614 or 07974 616 852 Web: www.medecinsdumonde.org.uk/projectlondon/
Project: London is an advocacy project providing information, advice and practical assistance to vulnerable people, to help them access NHS and other services.

British Lung Foundation

73-75 Goswell Road, London EC1V 7ER
Tel: Helpline 08458 50 50 20 Web: www.lunguk.org
Information about TB in various languages.