Overview
Tuberculosis, often called TB, is an infection caused by Mycobacterium tuberculosis bacteria. It most commonly affects the lungs, but it can also affect the lymph nodes, bones, brain, kidneys, and other organs. TB infection may be inactive, meaning the bacteria are in the body but not causing illness, or active, meaning the person is sick and may spread it to others if the lungs or throat are involved.
Key Symptoms
Symptoms of active TB in the lungs can include a cough that lasts several weeks, chest pain, coughing up sputum or blood, fever, night sweats, tiredness, and weight loss. Symptoms of TB outside the lungs depend on the body part affected. Some people with inactive TB infection have no symptoms at all.
Causes and Risk Factors
TB is caused by bacteria that spread through the air from a person with active TB disease of the lungs or throat. Spending a long time in close contact with someone who has infectious TB raises the chance of exposure. Risk of becoming sick is higher in people with HIV, diabetes, undernutrition, certain immune-suppressing conditions or medicines, tobacco use, and people living or working in crowded settings.
Who Is Affected
TB can affect people of any age in every region of the world. It is more common in communities with limited access to healthcare, crowded living conditions, and higher rates of HIV or undernutrition. Healthcare workers, household contacts of a person with TB, and people living in shelters, prisons, or refugee settings may have higher exposure risk.
Prevention
Preventing TB includes early testing and treatment, especially after close exposure or if a person has risk factors for progression from infection to disease. Good ventilation, reducing overcrowding where possible, and infection-control measures in healthcare and group settings can lower spread. In some countries, BCG vaccination is used to help protect infants and young children from severe forms of TB.
Diagnosis and Tests
Healthcare professionals may use a skin test or a blood test to look for TB infection. If TB disease is suspected, common tests include a chest X-ray and laboratory testing of sputum or samples from the affected body area. Testing helps distinguish inactive TB infection from active TB disease, which is important because treatment plans differ.
Treatment Categories
TB disease is treated with a combination of prescription medicines over a period of time, and treatment should be guided by a qualified healthcare professional. It is very important to take treatment exactly as instructed and complete the full course, because stopping early can lead to treatment failure and drug-resistant TB. Inactive TB infection may also be treated to reduce the chance of future active disease.
When to Seek Medical Care
Seek medical care if you have a cough lasting more than a few weeks, fever, night sweats, unexplained weight loss, chest pain, or if you have been in close contact with someone diagnosed with TB. You should also seek care if you have HIV or another condition that weakens the immune system and think you may have been exposed. Early evaluation can help protect both your health and the health of people around you.
When It May Be an Emergency
Get urgent medical help right away if you are coughing up significant blood, have severe trouble breathing, confusion, extreme weakness, or signs of severe illness. Emergency care is also important for infants, older adults, or people with weakened immune systems who become very unwell. These symptoms can have serious causes, including severe TB or another urgent lung condition.