Overview
Tuberculosis is an infectious disease caused by TB bacteria. It most commonly affects the lungs, but it can also involve lymph nodes, bones, kidneys, the brain, and other organs. There are two main forms: latent TB infection, where the bacteria are in the body but not causing illness, and active TB disease, where the bacteria are multiplying and causing symptoms. Active TB, especially in the lungs or throat, can spread to other people.
Key Symptoms
Latent TB infection usually causes no symptoms. Active TB disease in the lungs often causes a cough that lasts for weeks, chest pain, coughing up blood or mucus, fever, night sweats, tiredness, and weight loss. TB in other parts of the body can cause different symptoms depending on the organ involved. Symptoms may develop slowly, which can delay testing and care.
Causes and Risk Factors
TB is caused by Mycobacterium tuberculosis bacteria. It spreads through the air when a person with active TB of the lungs or throat releases tiny droplets by coughing, sneezing, speaking, or singing. Risk is higher with close or prolonged contact, living or working in crowded settings, a weakened immune system, HIV infection, diabetes, undernutrition, smoking, or certain medicines that reduce immune function. Not everyone exposed to TB becomes infected, and not everyone infected develops active disease.
Who Is Affected
TB can affect people of any age in every region of the world. It is more common in places where TB is widespread and in communities facing overcrowding, poor ventilation, poverty, or limited access to healthcare. People who live with or spend a lot of time around someone with active TB are at higher risk. Babies, older adults, and people with weakened immune systems can be especially vulnerable to severe disease.
Prevention
Prevention includes early detection and treatment of active TB, testing people who have been exposed, and treating latent TB infection when recommended by a healthcare professional. Good ventilation, reducing close exposure to someone with suspected or confirmed infectious TB, and infection-control measures in healthcare and community settings can lower spread. In some countries, the BCG vaccine is used to help protect young children from severe forms of TB. Public health follow-up is an important part of preventing transmission.
Diagnosis and Tests
Testing for TB may include a skin test or a blood test to look for TB infection. If active TB is suspected, healthcare professionals may use a chest X-ray and examine sputum or other body samples to look for the bacteria. Additional tests may be needed if TB outside the lungs is possible. Testing also helps tell the difference between latent TB infection and active TB disease, which is important for treatment decisions.
Treatment Categories
Treatment depends on whether a person has latent TB infection or active TB disease. Active TB usually requires a combination of medicines over several months, with close follow-up to make sure treatment is completed and to reduce the risk of drug resistance. Latent TB infection may also be treated to lower the chance of future active disease. People should follow public health and healthcare instructions carefully and report side effects or trouble taking medicines.
When to Seek Medical Care
Seek medical care if you have a cough lasting more than a few weeks, unexplained fever, night sweats, weight loss, coughing up blood, or close contact with someone diagnosed with TB. Medical care is also important after travel or residence in places where TB is common if symptoms develop. People with HIV, weakened immune systems, or other health conditions that increase TB risk should seek evaluation promptly if exposed or symptomatic. Early assessment can help identify infection and reduce spread to others.
When It May Be an Emergency
Urgent medical attention is needed for severe shortness of breath, coughing up significant amounts of blood, confusion, severe weakness, or signs of serious illness. Emergency care may also be needed if a person with possible TB is very ill, dehydrated, or unable to stay awake. TB affecting the brain or other critical organs can be life-threatening. Do not delay urgent evaluation if severe symptoms are present.