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Tuberculosis (TB)Published by Bupa's health information team, healthinfo@bupa.com, February 2008. This factsheet is for people who have tuberculosis (TB), or who would like information about it. TB is an infectious disease caused by a type of bacterium. It can lead to serious complications and even death, especially if the body is weakened by other health problems. TB is rare in the UK due to a large-scale vaccination programme, and it can usually be treated with antibiotics. However, it's a very common cause of death in less developed parts of the world. About TBTB is an infectious disease caused by a bacterium called Mycobacterium tuberculosis. It's mainly a lung disease, but it can affect other parts of the body such as the skin or other organs. TB worldwideThe World Health Organisation (WHO) estimates that about one third of the world's population (two billion people) is infected with M. tuberculosis. One in 10 of these will go on to develop the disease. Most cases of TB occur in developing countries in Africa and Asia. In 2005, TB killed 1.6 million people; over half of these deaths occurred in Asia. In the UK, about 8,000 cases of TB are reported each year, but this number is rising slowly. Nearly half of all cases in the UK occur in London. SymptomsMany people who become infected with TB don't realise they have been exposed to the infection because their immune system successfully fights it off. When this happens, the bacteria become coated in tiny tubercles (round lesions), usually in the lungs. These can sometimes be seen on a chest X-ray. The bacteria are still in the body, but there are no symptoms and it can't be passed on to other people. This is called latent TB. Depending on how effectively your immune system fights the infection, you may have:
If your immune system successfully fights the infection, you will be immune to TB. Sometimes latent tuberculosis becomes active years later. This is known as post-primary TB, and is more likely to happen if your immune system is weakened by other problems such as HIV, poorly controlled diabetes, or if you are underweight. About one in 10 people infected with TB bacteria go on to develop active TB at some point in their life. Active TB bacteria aren't contained in tubercles, and a person with active TB will have symptoms, which may include:
At first, a TB infection normally affects the lungs. This is called pulmonary TB. However, TB often spreads to the lymph nodes (glands throughout your body that are part of your immune system). It can also affect your bones, joints and kidneys, as well as cause meningitis (inflammation of the membranes surrounding the brain and spinal cord). CausesYou can catch TB by breathing droplets in the air that contain the bacterium M. tuberculosis. These are spread through the air when someone with TB coughs or sneezes. TB is only infectious when it affects the lungs (See Symptoms). Although it's spread through the air, you need to be closely exposed to a person with TB for some time before you catch it. People most commonly catch TB from people they live or work with. You are more likely to get TB if you:
DiagnosisThe most common test for TB is the tuberculin test. The test detects latent TB and is also used as part of vaccination programmes. There are two ways to do the test. The most common one is called the Heaf test. A small device with six small needles is pressed onto the skin of your forearm. The needles carry tiny amounts of tuberculin protein, which comes from the bacteria that cause TB. One week later, a doctor or nurse will examine the skin at the site of the test to see if there has been a reaction. An alternative, the Mantoux test involves injecting the tuberculin protein into your skin. You will get the results 48 hours after the test. In either case, the doctor or nurse is looking for a raised red reaction on your skin. This is a positive result, meaning you have been exposed to the TB bacteria. The reaction is then graded. A weak reaction suggests that you have developed some immunity to the disease. A strong reaction means the problem may need further investigation and diagnosis. If you have no reaction, you haven't been exposed to TB, which means you can be immunised (see Immunisation). The test for active TB involves analysis of a sample of your phlegm. This can also identify which combination of drugs is likely to treat it successfully. A chest X-ray can also diagnose active TB. TreatmentPeople with either active or latent TB are treated with a combination of antibiotic tablets to kill the bacteria. Treating latent TB prevents the infection becoming active. You may need to go to hospital for the first week or so, especially if you are very ill or thought to be very infectious. However, some people can be treated at home. MedicinesYou will usually need to take antibiotics for six months. You may need a longer course of treatment if the bacteria are resistant to one or more of the antibiotics (See Drug resistant TB). It's very important to take the full six-month course of antibiotics and to take them regularly, otherwise the bacteria may develop resistance to the antibiotics. Treatment with antibiotics is usually effective, provided that the full course of medication is taken as prescribed. Some people may get side-effects from the antibiotics. These can include:
If you notice any of these symptoms, don't stop taking the medication, but talk to your doctor as soon as you can - an alternative treatment may be needed. Drug resistant TBThe bacteria that causes TB can, in rare cases, become resistant to antibiotics, making it extremely difficult to treat. According to the World Health Organisation (WHO), multidrug resistant tuberculosis (MDR TB) has been found in most countries surveyed. Drug resistant TB is more likely to develop if you don't finish your antibiotic treatment course for TB. PreventionImmunisationIn the UK, a large-scale immunisation programme is run to help prevent TB. Immunisation is given as the BCG (Bacillus Calmette-Guérin) vaccination. This protects between 70 and 80 percent of people who receive it. It lasts for at least 15 years. The vaccination strategy in the UK targets people who are most at risk of getting TB, such as:
The vaccination isn't usually recommended for people over 45 unless they are in a high-risk group such as healthcare workers. Once you have had the immunisation, you won't need to have it again. Before giving the vaccination, your doctor or nurse must first check whether you are already immune to TB. This is done with the tuberculin test (see Diagnosis). If the test is positive, this means you have been exposed to the TB bacteria and you are already immune. You will not be given the BCG vaccination. Depending on the size of the skin reaction, you may be referred for more tests, such as an X-ray and a phlegm test, and possibly treatment for TB. People who aren't already immune are given the vaccination either as a single needle injection, or with a multiple needle device similar to the one used for the Heaf test. The injection is given to the top of the left arm (or the right arm in left-handed people). It's rare to get a strong reaction to the vaccination, but a small ulcer on the skin of the arm often forms. This may take several weeks to heal properly. A flat scar often develops later. This is normal and a sign of successful immunisation. Further information
Sources
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Dr James Quekett, Bsc.MB Ch.B MRCGP DRCOG DFFP, partner/principal general practitioner at Rowcroft Medical Centre, and by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional. Publication date: February 2008. Expected review date: February 2010.
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