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Tuberculosis (TB)

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Tuberculosis (TB)



Introduction 

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:


a persistent 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


You should see a GP if you have a cough that lasts more than three weeks or if you cough up blood.

 

What causes tuberculosis?

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 defence 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.

 

Who is affected?

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.

 

How tuberculosis is treated

With treatment, TB can usually be cured. Most people will 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 you are infected with a drug-resistant form of TB, treatment can last as long as two years.

If you are in close contact with someone who has TB, tests may be carried out to see if you are also infected. These can include a chest X-ray, blood tests, and a skin test called the Mantoux test.

 

Tuberculosis vaccination

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.

It's also recommended some people, such as healthcare workers, are vaccinated because of the increased risk of contracting TB while working.

 

Countries with high TB rates

Parts of the world that 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

the western Pacific region (to the west of the Pacific Ocean) – including Vietnam and Cambodia


For a world map showing countries with high rates of TB, see the World Health Organization (WHO) website.

 

Symptoms of tuberculosis 

The symptoms of tuberculosis (TB) depend on where the infection occurs.

TB usually develops slowly. Your symptoms might not begin until months or even years after you were initially infected.

In some cases the infection doesn't cause any symptoms, which is known as latent TB. It's called active TB if you have symptoms. You should contact your GP if you or your child have symptoms of TB.

 

Main symptoms

General symptoms of TB include:


lack of appetite and weight loss

a high temperature (fever)

night sweats

extreme tiredness or fatigue


These symptoms can have many different causes, however, and are not always a sign of TB.

 

Additional symptoms

TB can also cause additional symptoms depending on which part of the body is infected.

 

Pulmonary TB

Most infections affect the lungs, which can cause:


a persistent cough that lasts more than three weeks and usually brings up phlegm, which may be bloody

breathlessness that gradually gets worse


This is known as pulmonary TB.

 

Extrapulmonary TB

Less commonly, TB infections develop in areas outside the lungs, such as the lymph nodes (small glands that form part of the immune system), the bones and joints, the digestive system, the bladder and reproductive system, and the nervous system (brain and nerves).

This is known as extrapulmonary TB.

Symptoms of extrapulmonary TB vary, but can include:


persistently swollen glands

abdominal (tummy) pain

pain and loss of movement in an affected bone or joint

confusion

a persistent headache

seizures (fits)


Extrapulmonary TB is more common in people with a weakened immune system, such as those with HIV.

 

Causes of tuberculosis 

Tuberculosis (TB) is caused by a type of bacterium called Mycobacterium tuberculosis.

The condition is spread when a person with an active TB infection in their lungs coughs or sneezes and someone else inhales the expelled droplets, which contain TB bacteria.

Although it is spread in a similar way to a cold or the flu, TB is not as contagious. You would usually have to spend prolonged periods in close contact with an infected person to catch the infection yourself.

For example, TB infections usually spread between family members who live in the same house. It would be highly unlikely to become infected by sitting next to an infected person on a bus or train.

Not everyone with TB is infectious. Generally, children with TB or people with TB that occurs outside the lungs (extrapulmonary TB) do not spread the infection.

 

Latent or active TB

In most healthy people the immune system is able to destroy the bacteria that cause TB. However, in some cases the bacteria infect the body but don't cause any symptoms (latent TB), or the infection begins to cause symptoms within weeks or months (active TB).

Up to 10% of people with latent TB eventually develop active TB years after the initial infection. This usually happens when the immune system is weakened – for example, during chemotherapy.

 

Who's most at risk?

Anyone can catch TB, but people particularly at risk include those:


who live in, come from, or have spent time in a country or area with high levels of TB – around three in every four TB cases in the UK affect people born outside the UK

in prolonged close contact with someone who is infected

living in crowded conditions

with a condition that weakens their immune system, such as HIV

having treatments that weaken the immune system, such as corticosteroids, chemotherapy or tumour necrosis factor (TNF) inhibitors (used to treat some types of arthritis and certain gut conditions)

who are very young or very old – the immune systems of people who are young or elderly tend to be weaker than those of healthy adults

in poor health or with a poor diet because of lifestyle and other problems, such as drug misuse, alcohol misuse, or homelessness


 

Diagnosing tuberculosis 

Several tests are used to diagnose tuberculosis (TB), depending on the type of TB suspected.

Your GP may refer you to a TB specialist for testing and treatment if they think you have TB.

Pulmonary TB

A diagnosis of pulmonary TB (TB that affects the lungs) can be difficult and several tests are usually needed.

This will include a chest X-ray to look for changes in the appearance of your lungs that are suggestive of TB. Samples of phlegm will also often be taken and checked for the presence of TB bacteria.

These tests are important in helping to decide on the most effective treatment for you.

 

Extrapulmonary TB

If you have suspected extrapulmonary TB (TB that occurs outside the lungs), several tests can be used to confirm a diagnosis. These may include:


a computerised tomography (CT) scan, magnetic resonance imaging (MRI) scan, or ultrasound scan of the affected part of the body

urine and blood tests

a biopsy – a small sample of tissue or fluid is taken from the affected area and tested for TB bacteria


You may also have a lumbar puncture. This involves taking a small sample of cerebrospinal fluid (CSF) from the base of your spine. CSF is fluid that surrounds the brain. It can be checked to see whether TB has infected your central nervous system (brain and spinal cord).

 

Screening for latent TB

In some circumstances, you may need to be tested to check for latent TB (when you have been infected with TB bacteria but do not have any symptoms).

For example, you may need to be screened if you have been in close contact with someone known to have an active TB infection (an infection that causes symptoms), or if you have recently spent time in a country where TB levels are high.

If you have just moved to the UK from a country where TB is common, you may be screened when you arrive or your GP may suggest screening when you register as a patient.

 

Mantoux test

The Mantoux test is a widely used test for latent TB. It involves injecting a substance called PPD tuberculin into the skin of your forearm. It's also called the tuberculin skin test (TST).

If you have a latent TB infection, your skin will be sensitive to PPD tuberculin and a hard red bump will develop at the site of the injection, usually within 48 to 72 hours of having the test. If you have a very strong skin reaction, you may need a chest X-ray to confirm whether you have an active TB infection.

If you do not have a latent infection, your skin will not react to the Mantoux test. However, as TB can take a long time to develop, you may need to be screened again at a later stage.

If you have had the BCG vaccination, you may have a mild skin reaction to the Mantoux test. This does not necessarily mean you have latent TB.

 

Interferon gamma release assay (IGRA)

The interferon gamma release assay (IGRA) is a newer type of blood test for TB that is becoming more widely available.

The IGRA may be used to help diagnose latent TB:


if you have a positive Mantoux test

if you previously had the BCG vaccination (as the Mantoux test may not be reliable in these cases)

as part of your TB screening if you have just moved to the UK from a country where TB is common

as part of a health check when you register with a GP

if you are about to have treatment that will suppress your immune system

if you are a healthcare worker


 

Treating tuberculosis 

Treatment for tuberculosis (TB) will usually involve a long course of antibiotics lasting several months.

While TB is a serious condition that can be fatal if left untreated, deaths are rare if treatment is completed.

For most people, a hospital admission during treatment is not necessary.

 

Pulmonary TB

If you are diagnosed with active pulmonary TB (TB that affects your lungs and causes symptoms), you will be given a six-month course of a combination of antibiotics. The usual course of treatment is:


two antibiotics (isoniazid and rifampicin) every day for six months

two additional antibiotics (pyrazinamide and ethambutol) every day for the first two months


It may be several weeks or months before you start to feel better. The exact length of time will depend on your overall health and the severity of your TB.

After taking the medicine for two weeks, most people are no longer infectious and feel better. However, it is important to continue taking your medicine exactly as prescribed and to complete the whole course of antibiotics.

Taking medication for six months is the most effective method of ensuring the TB bacteria are killed. If you stop taking your antibiotics before you complete the course, or you skip a dose, the TB infection may become resistant to the antibiotics. This is potentially serious as it can be difficult to treat and will require a longer course of treatment.

If you find it difficult to take your medication every day, your treatment team can work with you to find a solution. This may include having regular contact with your treatment team at home, the treatment clinic, or somewhere else more convenient.

If treatment is completed correctly, you should not need any further checks by a TB specialist afterwards. However, you may be given advice about spotting signs that the illness has returned, although this is rare.

In rare cases TB can be fatal, even with treatment. Death can occur if the lungs become too damaged to work properly.

 

Extrapulmonary TB

Extrapulmonary TB (TB that occurs outside the lungs) can be treated using the same combination of antibiotics as those used to treat pulmonary TB. However, you may need to take them for 12 months.

If you have TB in areas such as your brain, you may also be prescribed a corticosteroid such as prednisolone for several weeks to take at the same time as your antibiotics. This will help reduce any swelling in the affected areas.

As with pulmonary TB, it's important to take your medicines exactly as prescribed and to finish the whole course.

 

Latent TB

Latent TB is when you have been infected with the TB bacteria but do not have any symptoms of active disease. Treatment for latent TB is usually recommended for:


people aged 35 years or under 

people with HIV, regardless of their age

healthcare workers, regardless of their age 

people with evidence of scarring caused by TB, as shown on a chest X-ray, but who never received treatment 


Treatment is not recommended for people who have latent tuberculosis and are over the age of 35, do not have HIV and are not healthcare workers. This is because the risk of liver damage caused by antibiotic treatment increases with age, and the risks of treatment may outweigh the benefits.

Latent TB is also not always treated if it's suspected to be drug resistant. If this is the case, you may be regularly monitored to check the infection does not become active.

In some cases, testing and treatment for latent TB may be recommended for people who require treatment that will weaken their immune system, such as long-term corticosteroids, chemotherapy or TNF inhibitors. This is because there is a risk of the infection becoming active.

Treatment for latent TB generally involves either taking a combination of rifampicin and isoniazid for three months, or isoniazid on its own for six months.

 

Side effects of treatment

Rifampicin can reduce the effectiveness of some types of contraception, such as the combined contraceptive pill. Use an alternative method of contraception, such as condoms, while taking rifampicin.

In rare cases the antibiotics used to treat TB can cause damage to the liver or eyes, which can be serious. Your liver function therefore may be tested before you begin treatment.

If you are going to be treated with ethambutol, your vision should also be tested at the beginning of the course of treatment.

Contact your TB treatment team if you develop any worrying symptoms during treatment, such as:


being sick 

yellowing of your skin and whites of your eyes (jaundice)

an unexplained high temperature (fever)

tingling or numbness in your hands or feet

a rash or itchy skin

changes to your vision, such as blurred vision


 

Preventing the spread of infection

If you are diagnosed with pulmonary TB, you will be contagious up to about two to three weeks into your course of treatment.

You will not normally need to be isolated during this time, but it's important to take some basic precautions to stop TB spreading to your family and friends. You should:


stay away from work, school or college until your TB treatment team advises you it is safe to return 

always cover your mouth – preferably with a disposable tissue – when coughing, sneezing or laughing

carefully dispose of any used tissues in a sealed plastic bag 

open windows when possible to ensure a good supply of fresh air in the areas where you spend time

do not sleep in the same room as other people as you could cough or sneeze in your sleep without realising it


 

What if someone I know has TB?

When someone is diagnosed with TB, their treatment team will assess whether other people are at risk of infection. This may include close contacts, such as people living with the person who has TB, as well as casual contacts, such as work colleagues and social contacts.

Anyone who is assessed to be at risk will be asked to go for testing, and will be given advice and any necessary treatment after their results. See diagnosing tuberculosis for more information about this.
 


Tuberculosis