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Overview
What Is Tuberculosis?
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis, a bacterium that most often affects the lungs. A person can have latent tuberculosis infection, meaning the bacteria are present but inactive and cause no symptoms. Active tuberculosis disease occurs when the bacteria multiply and cause illness, which may affect the lungs or other organs. TB can affect people of any age and remains a serious infectious disease worldwide.
Symptoms
Tuberculosis Symptoms
Latent tuberculosis usually causes no symptoms, while active TB can cause illness that develops gradually. Symptoms vary depending on whether the lungs or another organ is affected. Having one or more of these symptoms does not confirm TB, but persistent symptoms or a known exposure should be assessed by a healthcare professional.
- A cough lasting three weeks or longer may occur with pulmonary TB.
- Coughing up blood or sputum can be a sign of active lung disease.
- Chest pain may occur, especially with breathing or coughing.
- Fever can develop as the body responds to infection.
- Night sweats may occur even when the room is cool.
- Unexplained weight loss can occur as active TB progresses.
- Loss of appetite is a possible symptom of active tuberculosis.
- Fatigue or unusual tiredness may accompany the infection.
WHEN SYMPTOMS MATTER
Persistent symptoms need evaluation
Contact a healthcare professional about persistent respiratory symptoms or symptoms after a known TB exposure. Do not rely on symptoms alone to diagnose tuberculosis, because other conditions can cause similar problems.
How It Spreads
How Tuberculosis Spreads
Active tuberculosis of the lungs or throat can release bacteria into the air when an infected person coughs, speaks, or sings. Transmission is more likely during prolonged close contact, especially indoors or in poorly ventilated spaces. Latent TB infection is not contagious, and TB is not usually spread through brief casual contact.
| Feature | Latent TB infection | Active TB disease |
|---|---|---|
| Symptoms | Usually no symptoms | May cause cough, fever, night sweats, weight loss, or symptoms related to another affected organ |
| Ability to spread TB | Does not generally spread TB | Pulmonary or throat disease may spread bacteria through the air |
| Need for medical treatment | Treatment is often recommended to prevent active disease | Requires prompt treatment with prescribed medicines |
Risk Factors
Tuberculosis Risk Factors
Factors that increase exposure
- Close contact with someone who has active TB increases the chance of inhaling Mycobacterium tuberculosis.
- Living in or traveling to an area where TB is common increases exposure risk.
- Living or working in a congregate setting, such as a shelter, prison, or residential facility, can increase exposure.
- Working in healthcare or a laboratory may increase occupational exposure to TB.
Factors that increase progression to active disease
- HIV infection can weaken immune defenses and increase the risk of active TB.
- Recent TB infection carries a higher risk of progressing to active disease.
- Other weakened immune defenses, including those caused by immune-suppressing medicines, can increase risk.
- Diabetes is associated with a higher risk of active tuberculosis.
- Certain cancers can impair immune protection against TB.
- Chronic kidney disease can increase the likelihood of active disease.
- Silicosis, a lung disease caused by silica exposure, increases TB risk.
- Tobacco use is a modifiable factor associated with greater risk of TB disease.
- Substance use can increase risk through effects on health, immunity, and living conditions.
Complications
Tuberculosis Complications
Untreated active TB can worsen and spread from the lungs to other parts of the body. The risk of complications depends on the organs affected, immune status, how advanced the disease is, and the response to treatment. Early diagnosis and a complete treatment plan can substantially reduce these risks.
- Permanent lung damage can result from severe or prolonged pulmonary TB.
- Respiratory failure may occur when lung function becomes severely impaired.
- Coughing up significant amounts of blood can be a serious complication of lung disease.
- Pleural disease can cause inflammation or fluid around the lungs.
- TB meningitis can affect the membranes surrounding the brain and spinal cord.
- Infection of bones or joints can cause pain, swelling, and impaired movement.
- Kidney involvement can damage kidney tissue or affect urinary function.
- Widespread, or miliary, TB can spread through the bloodstream to multiple organs.
TREATMENT MATTERS
Do not stop TB medicines early
Complete the prescribed regimen and attend follow-up appointments, even if symptoms improve. This helps reduce complications and allows clinicians to identify treatment failure or drug resistance.
Diagnosis
How Tuberculosis Is Diagnosed
TB diagnosis depends on symptoms, exposure history, immune status, and whether clinicians are evaluating latent infection or active disease. A healthcare professional may use an examination, medical history, infection testing, imaging, and laboratory testing. The evaluation also helps determine where the disease is located and whether the bacteria may resist particular medicines.
| Evaluation | What it helps show | Examples |
|---|---|---|
| Testing for latent TB infection | Whether the immune system has responded to TB bacteria | Tuberculin skin test or TB blood test |
| Imaging for active disease | Whether the lungs or other areas show changes consistent with TB | Chest X-ray or other chest imaging |
| Laboratory testing for active disease | Whether TB bacteria are present and which medicines may work | Microscopic examination, culture, or molecular testing of sputum |
Treatment & Management
Tuberculosis Treatment and Management
Tuberculosis is usually curable with a prescribed combination of antibiotics. Treatment selection and duration depend on whether the person has latent or active disease, the drug susceptibility of the bacteria, the affected organs, and overall health. A clinician or public-health team may provide monitoring and support throughout treatment.
Treatment approaches by disease status
- Latent TB infection is treated with one or more prescribed medicines to lower the chance of developing active disease.
- Drug-susceptible active TB is treated with multiple antibiotics taken together according to a specialist or public-health regimen.
- Drug-resistant TB requires a specialist-directed combination of medicines, with treatment adjusted to laboratory susceptibility results.
DURING TREATMENT
Follow the full treatment plan
Take every dose as prescribed, report side effects promptly, and attend monitoring visits. Follow public-health instructions about masking, limiting close contact, or other steps to reduce transmission when active TB may be contagious.
Prevention
Tuberculosis Prevention
- Testing people with relevant exposure or risk can identify TB infection before active disease develops.
- Treating latent TB infection when recommended can reduce the chance of progression to active disease.
- Completing treatment for active TB helps protect the individual and reduce transmission.
- Improving indoor ventilation can reduce the concentration of airborne bacteria.
- Using recommended respiratory precautions in healthcare or other high-risk settings can lower exposure.
- Evaluating close contacts helps identify people who may need testing or preventive treatment.
Outlook and Prognosis
Tuberculosis Outlook and Prognosis
Latent TB can often be prevented from becoming active disease with appropriate preventive treatment. Active TB is generally curable when diagnosed early and treated with an effective, complete regimen. Without effective treatment, however, tuberculosis can cause lasting disability or be fatal.
- The site and severity of disease affect recovery and the risk of lasting complications.
- Strong immune function generally supports a better response to treatment.
- HIV co-infection can increase complications and requires coordinated care.
- Drug-resistant TB can make treatment longer or more complex.
- Taking medicines as prescribed improves the chance of cure.
- Timely diagnosis and treatment are associated with better outcomes than delayed care.
When Should You See a Doctor
When Should You See a Doctor for Tuberculosis?
- Contact a clinician promptly about a cough lasting three weeks or longer.
- Seek medical evaluation if you cough up blood.
- Unexplained weight loss or night sweats should be assessed, especially with other tuberculosis symptoms.
- Known close contact with someone who has active TB requires professional advice about testing.
- A positive TB test requires follow-up to determine whether infection is latent or active.
- People with high-risk immune conditions should seek advice promptly after possible exposure or symptoms.
SEEK URGENT HELP
Severe symptoms need emergency care
Seek local emergency care for severe breathing difficulty, significant bleeding, confusion, fainting, or rapidly worsening illness.
Branches
2 topics
Tuberculosis
Infectious Diseases
Tuberculosis
Pulmonology
Symptoms
2 topics
