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What is tuberculosis (TB)?


Tuberculosis (TB) is caused by bacteria called Mycobacterium tuberculosis and is the single biggest cause of illness and death in people with HIV around the world.

In the UK, it is one of the most common AIDS-defining illnesses. With the right treatment and care, however, it can be cured.

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Will TB make me ill?

Some people become ill soon after they are infected with TB. This is called ‘active’ TB.

However, people can also have ‘latent’ TB. This is sometimes called ‘dormant’ TB and it means that TB is present in the body but not causing illness. It can become active again at a later stage. Sometimes, people do not develop symptoms until many years after they were infected with TB.

Usually, people have TB in their lungs (called pulmonary TB), but it can affect other parts of the body, such as the bones or kidneys.

You could be at greater risk of developing TB if you come from a part of the world where TB is more common (parts of Africa and Asia, for example), if you spend a lot of time with someone with active TB, or if you are not in good health.

What are the symptoms of TB?

TB usually affects the lungs. A common symptom of TB is a cough that lasts several weeks or longer and that produces phlegm (mucus or sputum), which can be bloody. Other symptoms include:

  • high temperature
  • fevers
  • night sweats
  • weight loss
  • shortness of breath
  • chest pain

It’s important to tell your doctor if you have any of these symptoms. You will then need to have tests to see if you have TB. The standard test is to have a chest X-ray. The disease often shows up as ‘shadows’ or white patches on the lungs. Samples of your sputum will be tested. This can tell if you have active TB and are infectious.

If doctors are having difficulty finding out what is causing your illness, they may do a bronchoscopy (putting a tube with a camera through your nose into your lungs) or a biopsy (taking a sample of tissue from your lungs). You will have an anaesthetic for these procedures.

In some cases, TB can spread into other parts of the body. These can include lymph nodes, the gut, the spine, the liver and the brain. It is more common in people whose immune system is very weakened. If you have any symptoms suggesting your TB has spread, you will have other tests to confirm this.

There are also tests that can tell if you have latent TB. You might be tested for this because it’s more likely that you will go on to develop active TB if you also have HIV, especially if you have a low CD4 count or are not on HIV treatment.

How is TB transmitted?

TB is normally passed on to other people when someone with ‘active’ TB coughs or sneezes, in the same way a cold is spread. However, TB is not as easily passed on as a cold. You need to spend a lot of time with the infected person to be at risk of getting TB – for example, living in the same house with them.

People who have ‘latent’ TB and are not unwell are not infectious. And people are only infectious if they have TB in their lungs or throat, not if they have TB in another part of their body.

How is TB treated?

If you are HIV positive and have latent (dormant) TB, your doctor may recommend a course of treatment to reduce the risk that you will develop active TB. This is often called TB prophylaxis.

You will be treated with the anti-TB drug isoniazid for six months, or isoniazid with another drug, rifampicin, for four months. This has been shown to reduce the risk that you will develop active TB.

TB that is causing illness is treated with a combination of antibiotics. Treatment usually lasts for six months. But sometimes people have to take treatment for longer. Researchers are looking at new combinations and doses of TB drugs to see if they can make the course of treatment shorter.

Usually, for the first two months, people take a combination of four different anti-TB drugs: isoniazid, rifampicin, pyrazinamide and ethambutol. After that, the treatment generally lasts another four months, just with the two drugs isoniazid and rifampicin.

The drugs used to treat TB can interact with other drugs, including a number of anti-HIV drugs, and can cause side-effects. Make sure you tell your doctor about any other medication you are on or any side-effects you are experiencing.

Seek medical advice urgently if you develop jaundice (yellowing of the skin or eyes), nausea or vomiting (feeling or being sick), a skin rash, tingling in your hands or feet, a fever or changes to your vision.

Usually, you are no longer infectious after two weeks of TB treatment, and you should start to feel better after a few weeks or months.

It is very important to take your TB treatment exactly the way your doctor tells you to, even when you start to feel better. If the drugs are not taken in the right way, TB can become resistant to the drugs used to treat it. This means the drugs will stop working on the TB. It can also mean the TB will come back.

Resistant TB is harder to treat and is much more serious. If TB is resistant to two or more of the main TB drugs, it is called multidrug-resistant tuberculosis (MDR-TB). MDR-TB can usually be treated successfully, but doctors will have to work out which drugs will work.

Some TB is resistant to many of the TB drugs available. This is called extensively drug-resistant TB (XDR-TB). Many of the cases seen in the UK have been in people with HIV.

Can TB and HIV be treated at the same time?

It can be difficult to treat TB and HIV at the same time. This is because some anti-HIV drugs can interact with anti-TB drugs.

In addition, taking HIV treatment when you have active TB can cause a condition called immune reconstitution inflammatory syndrome (IRIS). Find out more about HIV drug interactions.

If your CD4 cell count is below 100 you should start HIV treatment as soon as possible after starting anti-TB drugs.

If your CD4 cell count is between 350 and 100, it is recommended that you start HIV treatment as soon as possible, but you can wait up to two months after starting TB treatment if you and your doctor think it would be useful. This could be to help you get used to one treatment before starting the other.

If your CD4 cell count is above 350, it is up to you and your doctor to decide when it would be best for you to start your HIV treatment.

How can I avoid getting TB?

There is a vaccine against TB, called the BCG. You should not have this if you are HIV positive, as it is a ‘live’ vaccine. This means it uses a weakened form of the bacteria, and can cause you to become unwell with a TB-like illness.

Try to avoid contact with people who have active lung TB until they are no longer infectious. If you are exposed to someone with active TB, see your doctor as soon as possible.

One of the best ways to prevent TB if you have HIV is to ensure your immune system is as healthy as possible. HIV treatment is the best way to prevent damage to your immune system.

Eating a healthy, balanced diet, getting enough sleep and not taking drugs or drinking too much alcohol can also help keep your immune system strong.

If you are HIV positive and have latent (dormant) TB, sometimes your clinic may recommend a course of treatment to reduce the risk that you will develop active TB. This is called TB prophylaxis.

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The Information Standard: Certified member

This article was last reviewed on 20/12/2016 by Anna Peters

Date due for the next review: 19/12/2019

Content Author: S. Corkery (NAM)

Current Owner: Kerri Virani

More information:

British HIV Association guidelines for the treatment of TB/HIV coinfection 2011. BHIVA, 2011: http://www.nhs.uk/conditions/tuberculosis/pages/introduction.aspx 

TB Alert, The truth about TB (website) http://www.thetruthabouttb.org/