Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis, primarily affecting the lungs.
It spreads through the air when a person with lung TB coughs, sneezes, or spits, and only a small number of bacteria are needed to cause an infection.
Annually, 10 million people are infected with TB, and despite being preventable and treatable, it claims the lives of 1.5 million people each year, making it the leading infectious cause of death globally.
TB is the primary cause of death among people with HIV and contributes significantly to the rise of antimicrobial resistance.
While TB is widespread, it disproportionately impacts low- and middle-income countries, with nearly half of all TB cases occurring in eight countries: Bangladesh, China, India, Indonesia, Nigeria, Pakistan, the Philippines, and South Africa.
Around a quarter of the global population carries the TB bacteria, but most do not develop the disease. People who are not ill cannot spread the infection.
Those carrying TB bacteria have a 5–10% lifetime risk of developing the disease, but individuals with weakened immune systems—such as those living with HIV, malnutrition, diabetes, or those who smoke—are at higher risk.
Symptoms
Common symptoms of TB include:
- Persistent cough
- Chest pain
- Weakness or fatigue
- Weight loss
- Fever
- Night sweats
These symptoms can be mild and may persist for months, which often delays medical attention and increases the risk of spreading the disease.
If TB is suspected, healthcare providers will conduct tests, such as testing a sputum sample for TB bacteria in cases of lung TB, or testing samples from affected body fluids or tissues for non-lung TB.
The World Health Organization (WHO) recommends rapid molecular diagnostic tests as the preferred method for diagnosing TB, with other methods including sputum smear microscopy and chest X-rays.
TB infection occurs when the bacteria enter the body but remain dormant. It can develop into active TB disease if the immune system weakens. People with TB infection show no symptoms.
Healthcare providers use skin or blood tests to detect TB infection in individuals at risk, screening for active TB.
Treatment
TB is curable and is typically treated with a standard six-month regimen of four antibiotics, including rifampicin and isoniazid.
In some cases, TB bacteria may not respond to these drugs, leading to drug-resistant TB, which requires more complex and prolonged treatment.
TB treatment requires close supervision and support from healthcare workers or trained volunteers, as adherence to the treatment plan is crucial.
Incomplete treatment can result in drug resistance, which increases the risk of spreading the disease.
For individuals with latent TB infection (those infected but not yet sick), preventive treatment can be given to prevent the disease from developing. This treatment uses the same antibiotics but for a shorter duration.
Recent advances have reduced the length of preventive treatment to 1 to 3 months, compared to the previous six-month regimen.
