Tuberculosis (TB)

Tuberculosis (TB)

 What is tuberculosis?

Tuberculosis (TB) is an infection caused by a bacterium called Mycobacterium tuberculosis. It is one of the oldest diseases known to man and was once so common that every adult was thought to have experienced a bout of TB infection during their lives.

TB in the past was a serious illness and very prevalent in Ireland. Consumption, as TB used to be called, claimed the lives of up to a quarter of all adults in Britain during the 19th century.

Today, TB remains common in some parts of the world, especially Africa and South-East Asia.

TB is much less common in developed countries, such as Ireland. In European countries, the disease is more common in deprived city areas, among the homeless, alcoholics, older people, those who are HIV positive and among people who come into close contact with those suffering from TB.

How is TB spread?

TB is contagious and is caught by inhaling microscopic droplets containing the bacterium, which are produced when an infected person coughs or sneezes.

 The illness usually affects the lungs, but sometimes can spread to other organs. It gets its name from the tubercles, or hard lumps, that form on the lungs to contain the TB bacteria. There are two types of tubercular infection:

- Primary TB occurs when a person first becomes infected. This is when the body forms tubercles on the lungs to contain the bacteria. There are rarely any symptoms with primary TB.

- Problems only arise if the immune system weakens, as this can allow the bacteria to escape from the tubercles. This is known as post-primary TB, or reactivated TB. The bacteria can re-infect the lungs and may spread to other parts of the body.

What are the symptoms of TB?

An active infection of tuberculosis can cause any of the following symptoms:

The symptoms of TB are general and a diagnosis is not always easy as the disease can easily be mistaken for other things, such as pneumonia, bronchitis, lung cancer or a chest infection. There is a skin test (Mantoux Test) that detects TB or if a person has had TB, but it not always conclusive.

How is TB treated?

TB is treated with a cocktail of antibiotics, which are administered for at least six months. The illness must be treated with multiple drugs, as the bacteria can become resistant to individual drugs.

As each infected person can potentially infect 10 others a year on average if not treated properly, it is important that every patient is treated with a combination of drugs as early as possible.

While modern drugs are very effective against TB, the bacteria are becoming resistant to some of these drugs in some parts of the world so it is vital that response to treatment is monitored carefully and that the course of treatment is completed.

Can TB be prevented?

There is a vaccination against TB, the BCG injection, which is administered to all children in Ireland in the first few months of life.

The spread of TB can be prevented by contact tracing so that relatives and close friends of a person who is diagnosed with TB can be examined, have a chest x-ray and be given a tuberculin test. This makes it possible to detect TB at an early stage and reduce the risk of spreading the infection to other people.

What are the risks to people who are HIV positive?

Many people may have experienced primary TB without even knowing it, as their body’s immune system has trapped the bacteria within tubercles on the lungs. If the immune system is compromised by HIV, the TB bacteria has a much better opportunity of breaking out and infecting the lungs, pleura and other parts of the body.

TB and HIV make bad bedfellows. TB causes the death of more HIV patients worldwide than any other secondary illness. TB can cause the HIV virus to multiply more quickly and some of the drugs used to treat HIV symptoms are not advisable to be used alongside a treatment for TB, as they can both weaken the liver and kidneys.

HIV positive people are much more likely than the average person to contract TB. A special treatment regime must be drawn up for HIV positive people who contract TB.

People with HIV should be aware of the complications that TB can cause. If you have HIV and experience any of the symptoms described above, consult your GP and ask to be tested for TB infection as soon as possible.

What does the future hold?

There is a very effective vaccination against TB (BCG vaccination) and children should receive this immunisation to protect against future infection. This is given in maternity hospitals or in health centres soon after birth. It is separate to the primary immunisation scheme, which is administered by GPs using a set schedule.

People travelling to parts of Africa and South-East Asia may require a booster before they go.

In cases of TB infection, there is a treatment available, but it requires taking multiple antibiotics for a period of months. Patients must complete their treatment in full, or there is the risk of the bacteria adapting and becoming drug-resistant.

TB is a dangerous illness, especially for people with compromised immune systems and it does kill many people globally every year. But vaccination can spare most of us the discomfort of ever experiencing the full-blown disease, and multiple drug therapy can resolve the disease, even in HIV patients.

Early diagnosis is essential to stop the infection spreading from person to person.