Tuberculosis Q & A
What is tuberculosis?
Tuberculosis (TB) is a contagious, potentially fatal, infection caused by the airborne bacterium Mycobacterium tuberculosis, or, less commonly, similar bacteria.
TB was extremely common last century but, with the introduction of antibiotics, it has become less prevalent in Western societies. However, TB is still a major public health problem in less developed countries and among people who live in overcrowded and unsanitary conditions.
Although TB can affect any organ in the body, it most commonly affects the lungs, where the infection often first starts.
A person with TB can spread the bacteria through coughing, sneezing or laughing — or even talking. Tiny droplets are released into the air where they can be inhaled by others. However, it is fairly difficult for a healthy person to become infected with TB without prolonged close contact with someone who is infected.
There is a significant difference between being infected with TB and actually having the active disease. An infected person has the bacteria in their body, but their immune system protects them from the disease so they won’t have symptoms (this can often happen during a person’s childhood, where the symptoms may be no more than a mild ‘flu). TB infection that has no symptoms is sometimes called ‘latent TB’. This sort of TB is not contagious.
The TB bacteria may stay in the body for many years and can flare up to cause active disease later in life. In active TB, the bacteria multiply and attack various organs of the body. A person who has active TB, as well as carrying the bacteria, will usually show symptoms of TB and can spread it to others. Such a person needs to see a doctor immediately.
Who is most at risk of TB?
Anyone at all can catch TB regardless of where they live, how old they are, or whether they are rich or poor. However, there seem to be groups of people who are more likely to be at higher risk for active disease. These include:
- newly arrived immigrants and refugees from areas where the disease is prevalent, who caught the infection before they arrived in Australia;
- people in close contact with those who have TB;
- people with weakened immune systems (e.g. the elderly and people with HIV/AIDS);
- people who drink heavily or use intravenous drugs; and
- people who are poorly nourished.
In Australia there are approximately 1000 new cases of TB diagnosed each year — the majority are in people not born in Australia.
What are the symptoms of TB?
A person with TB infection but not the active disease will have no symptoms. If you’ve contracted active TB you may notice some or all of the following symptoms:
- feeling tired all the time;
- weakness;
- persistent cough;
- coughing up phlegm or blood;
- loss of appetite;
- weight loss;
- fever; and
- night sweats.
These symptoms can also occur with other types of lung disease so it is important to see a doctor to have your condition thoroughly investigated. A person with active TB disease may not necessarily feel very ill in the early stages, and may have a cough only from time to time. If you think you have been exposed to TB, see your doctor straight away.
Complications of TB
A TB infection may spread to and affect the reproductive organs of both men and women. It can spread to the joints, causing a condition known as tuberculous arthritis, with symptoms of inflammation and pain in the joints.
TB can also affect the skin, bowel, adrenal glands and heart, and even the brain, leading to tuberculous meningitis. This is a life-threatening condition that can lead to coma and brain damage.
Another life-threatening type of TB is miliary tuberculosis, where a large number of bacteria are released into the bloodstream and spread around the body. Symptoms include fever, chills, weakness, weight loss and difficulty in breathing. If the bacteria spread to the bone marrow, blood abnormalities can occur.
How is TB detected?
Often, the first sign of TB is on a chest X-ray, which might be done to help evaluate your various symptoms.
If you have been exposed to the disease or you are showing symptoms, your doctor may do a Mantoux skin test. You will be given an injection of a small amount of protein derived from TB bacteria into the skin of your forearm, and this will be examined about 2–3 days later. If the injection site is red or swollen, it indicates current or past infection. However, sometimes the Mantoux test can give a false-negative result (the test suggests you don’t have TB when you do) or a false-positive result (the test suggests you do have TB when you don’t).
Therefore, to confirm a diagnosis of TB, doctors need to identify the TB bacteria in a body fluid, such as sputum (phlegm) or urine, or body tissue removed for biopsy.
How is TB treated?
Active TB is treated with a number of different antibiotics taken together over a significant period — usually at least 6 months. It is very important to take all doses of the antibiotics for the entire period they are prescribed, to stop the TB bacteria becoming resistant to the medicines. Fortunately, most cases of TB in Australia are responsive to the antibiotics. Properly taken, TB medicines provide an almost 100 per cent cure rate.
Treating latent TB can reduce the risk of the person developing active TB. Usually, just one antibiotic can be taken, for 6–9 months.
Doctors often recommend treatment if you have latent TB and you:
- have HIV;
- are in close contact with someone with active TB;
- were recently infected with TB;
- are a child or adolescent;
- need to take medicines that suppress your immune system; or
- have a long-term health condition such as kidney failure or diabetes, especially if you are younger than 35.
Your doctor or specialist will monitor your TB treatment and may modify it depending on the results of tests.
Last Reviewed: 19 December 2007
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