Tuberculosis

Modern medicine is facing a resurgence of TB

Tuberculosis (TB) is a serious infection which usually affects the lungs.

It kills millions of people around the world each year, and concern is growing that the bacteria which causes the disease are increasingly growing resistant to current drugs.

What is tuberculosis?

TB is an infection caused by a bacterium called Mycobacterium Tuberculosis.

Any part of the body can be affected, but in most cases the lungs are affected first.

It is spread when an infected person coughs or sneezes, producing tiny bacteria-infested water droplets which are easily breathed in by others in the vicinity.

What happens when you are infected?

In most cases healthy people who breathe in the bacteria do not develop active TB. Instead, the bacteria are killed or neutralised by their immune system. At most they will experience mild, short-lived symptoms.

In about one in 20 cases - usually when the person infected is not in good health - the immune system fails to tackle the bacteria, which multiply and spread to other parts of the lung and body.

There is a third scenario. In some cases the immune system fails to kill all the bacteria, which can trigger active disease months or even years after the first infection.

What are the symptoms?

Symptoms tend to start with a dry irritating cough, which continues for months, and gets progressively worse.

Over time, patients start to cough up a lot of phlegm, which may contain traces of blood.

Other symptoms include: fever, sweats, feeling unwell, weight loss, pains in the chest, and poor appetite.

Left untreated, damage occurs to the lungs, leading to breathlessness.

Eventually, the infection may spread to other parts of the body.

If left untreated, about half of people with active TB eventually die of the infection.

How common is tuberculosis?

TB has been killing people for thousands of years. Tissue samples from Egyptian mummies over 4,000 years old show signs of being infected with the disease.

Some estimate that TB was responsible for around 20% of all deaths in England and Wales in the 17th and 18th centuries. In the 19th and 20th centuries there has been a steady decline in deaths from the disease in industrialised countries. This was given a boost by the development of penicillin and other antibiotics in he last 50 years.

But the decline began to level out in he 1980s and since then the incidence of the disease has started to increase again.

In the developing world TB has remained common. It causes more deaths world-wide than any other infectious disease - about three million a year.

Spread of the disease in the developing world has been blamed on poor nutrition, poor housing and poor general health. In particular, many people infected with HIV are also vulnerable to TB.

How is TB diagnosed?

A skin prick test can give an indication of infection.

However, a definitive diagnosis usually involves growing a sputum sample in the lab over six to eight weeks.

Newer, speedier tests are currently in development.

What is the treatment?

You need to take a combination of special antibiotics, including isoniazid, rifampicin, pyrazinamide, and often ethambutol, over a six month period.

Doctors stress that it is important to complete the course, even if you feel better.

Failure do so has been blamed for the growing problem of antibiotic resistance, which threatens to undermine the effectiveness of current treatments.

With treatment, most people make a full recovery.

Can TB be prevented?

Yes. The BCG (Bacillus Calmette-Guerin) vaccine, which contains a small number of modified TB bacteria, is thought to be more than 70% effective at preventing the disease.

In the UK it is offered to vulnerable groups.