Tuberculosis (TB) is an infectious disease caused by the Mycobacterium tuberculosis bacterium. It usually affects the lungs, although it can also affect other parts of the body such as the kidneys, brain, spine and skin. TB spreads through the air when infected people cough, sneeze or spit. About a quarter of the global population is estimated to have been infected with TB bacteria, however it is thought that only about 10 per cent of these will become ill. Those carrying the disease but without symptoms cannot transmit it. TB is usually treated with antibiotics, and without treatment it is fatal in about 50 per cent of cases.
Symptoms of active TB in the lung are:
TB in other parts of the body have different symptoms
If untreated, active TB is fatal and more than a million people die from the disease every year. Another complication is drug resistance: TB that does not respond to standard drugs is called drug-resistant TB and requires treatment with different medicines. Multidrug-resistant TB (MDR-TB) is caused by bacteria that do not respond to isoniazid and rifampicin, the two most effective first-line TB drugs. In some cases, extensively drug-resistant TB (XDR-TB) can develop, which leaves patients with very limited treatment options.
TB and HIV form a dangerous combination, with each speeding the other’s progress. TB is the leading cause of death among people with HIV. If untreated TB is fatal in 50 per cent of cases with more than a million people dying each year from the disease.
TB spreads through close contact with people who have active TB. When someone with active TB coughs, sneezes or spits they release small droplets containing the bacteria, which can be breathed in by others.
It spreads easily among people living in cramped conditions, for example in prisons and homeless shelters. People with weakened immune systems and smokers are also at higher risk of developing the disease if exposed to the bacterium.
Treatment for TB has traditionally been difficult because of the complex nature of the bacterium. The treatment for standard TB is to take a course of four different antibiotics for six months. If the bacterium is resistant to drugs the treatment regime can take up to two and a half years, depending how resistant the bacterium is. Some of the drugs are toxic and have unpleasant side effects. In 2025 the World Health Organization recommended a shorter, six-month drug treatment for multi-drug resistant TB.
If the treatment is not properly completed, the disease can become much harder to treat.
To prevent tuberculosis infection and spread, it is important to seek medical attention if you have symptoms like a prolonged cough, fever and unexplained weight loss. Getting tested for TB if you are at increased risk is also important. If you are diagnosed with the disease it is important to complete your course of drugs.
The Bacille Calmette-Guérin (BCG) vaccine is given to babies or small children to prevent TB but it is not suitable for adolescents and adults. It is only given to babies in the UK whose parents or grandparents come from a country where rates of TB are high or if they live in areas of the UK with high rates.
There are several new vaccines in the pipeline.
TB, known as the white death or consumption is an ancient killer – traces of it have been found on Egyptian mummies. It took hold in the rapidly urbanising populations of Europe and North America in the 18th and 19th centuries and is thought to have killed more people in history than any other pathogen.
Robert Koch announced the discovery of the TB bacterium on 24 March 1882 – now World TB day – which paved the way for early treatments and then the development of the vaccine by Albert Calmette and Camille Guérin in the early 20th century. The advent of antibiotics was a game-changer in tackling the disease – the world’s first ever randomised control trial took place in Edinburgh in the 1940s when researchers treated TB patients with the antibiotic streptomycin. Slowly the disease was all but wiped out across Europe thanks to antibiotics, improved living conditions and the vaccine.
However, this disease of poverty is still endemic in poorer countries and among poorer people in richer nations. In 2024, 5,480 people became unwell with TB in England – up 13 per cent from 2023, the largest recorded increase since 1970, and a continuation of a trend that started in 2021. More than 80 per cent of these cases occurred among people born outside the UK. Those living in unstable conditions, such as the homeless, are most likely to be diagnosed with the disease.
who.int/health-topics/tuberculosis
nhs.uk/conditions/tuberculosis-tb
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