Tuberculosis

Overview

Tuberculosis, often called TB, is an infectious disease caused by bacteria that most commonly affect the lungs. It can also involve other parts of the body, such as the lymph nodes, bones, kidneys, brain, or spine. TB spreads through the air when a person with active TB in the lungs or throat coughs, sneezes, speaks, or sings. It is not usually spread by touching, sharing food, or brief casual contact.

TB can be either latent or active. In latent TB infection, the bacteria are present in the body but are inactive and do not cause symptoms. A person with latent TB does not spread the disease to others. In active TB disease, the bacteria multiply and cause illness; this form can be contagious when it affects the lungs or throat. With appropriate medical care, TB can often be treated effectively, but treatment requires careful follow-up and completion of the prescribed plan.

Symptoms

Symptoms depend on where the infection is located. Pulmonary TB, which affects the lungs, is the most common form. Symptoms may develop slowly and can be mistaken for other respiratory illnesses.

• A cough that lasts for several weeks
• Coughing up blood or mucus
• Chest pain or discomfort when breathing or coughing
• Fever
• Night sweats
• Unexplained weight loss
• Loss of appetite
• Fatigue or weakness
• Chills

When TB affects areas outside the lungs, symptoms may vary. For example, TB in the spine may cause back pain, while TB in the lymph nodes may cause swelling in the neck or other areas. TB affecting the brain or its coverings can cause severe headache, confusion, or neurological symptoms and requires urgent medical attention.

Causes and Risk Factors

TB is caused by bacteria that spread through airborne particles. The risk of infection is higher with prolonged, close contact with someone who has contagious active TB, especially in crowded or poorly ventilated settings.

Not everyone exposed to TB becomes ill. The immune system may control the bacteria, leading to latent TB infection. However, latent TB can become active later, particularly if the immune system becomes weakened.

Risk factors for TB infection or progression to active disease may include:

• Close contact with a person who has active TB
• Living or working in crowded settings
• Travel to or residence in areas where TB is more common
• Weakened immune system due to illness or medical treatment
• Chronic health conditions that affect immunity
• Malnutrition or poor general health
• Substance use or smoking

People who have previously had TB should also inform their healthcare team, especially before starting treatments that may affect the immune system.

Diagnosis

Diagnosis of TB begins with a medical history, symptom review, and physical examination. A healthcare professional may ask about exposure to TB, travel history, previous TB testing, vaccination history, and any conditions that may affect immunity.

Tests used to investigate TB may include skin or blood tests to detect TB infection. These tests can show whether the immune system has encountered TB bacteria, but they do not always confirm active disease. If active TB is suspected, additional tests are usually needed.

For suspected lung TB, chest imaging may be performed to look for changes in the lungs. Sputum samples, which are mucus coughed up from the lungs, may be examined in a laboratory to detect TB bacteria and guide treatment decisions. In some cases, samples from other body fluids or tissues may be needed, depending on the affected area.

Because TB can resemble other conditions, a complete evaluation is important. Laboratory testing can also help determine whether the bacteria are sensitive to standard treatments, which is important for choosing an effective treatment plan.

Treatment Options

Treatment for TB depends on whether the infection is latent or active, the part of the body affected, the patient’s overall health, and laboratory results. TB treatment usually involves a combination of medicines taken for a prolonged period under medical supervision. It is important to follow the treatment plan exactly and complete the full course, even if symptoms improve earlier.

For active TB, treatment aims to eliminate the bacteria, relieve symptoms, prevent complications, and reduce the risk of spreading infection to others. Some people may need temporary isolation or infection-control measures until they are no longer contagious. Healthcare teams may monitor progress with follow-up visits, symptom checks, imaging, and laboratory tests.

Latent TB may also be treated to reduce the chance of developing active disease in the future, especially in people at higher risk. The decision to treat latent TB is made by a healthcare professional after assessing individual risks and benefits.

Some forms of TB may be resistant to usual treatments and require specialized care. Patients should not stop or change treatment without medical advice, as incomplete treatment can lead to ongoing illness and more difficult-to-treat infection.

When to See a Doctor

Medical evaluation is recommended if you have a persistent cough, unexplained fever, night sweats, weight loss, or fatigue, especially if symptoms last for several weeks. You should also seek medical advice if you have been in close contact with someone diagnosed with active TB, even if you feel well.

Urgent medical care is needed for coughing up blood, severe chest pain, shortness of breath, confusion, severe headache, neck stiffness, weakness in the arms or legs, or symptoms in a child, pregnant person, older adult, or someone with a weakened immune system.

If TB is suspected or diagnosed, follow the guidance of your healthcare team about testing, treatment, follow-up appointments, and precautions to protect others. Early assessment and consistent care are important for managing TB safely.