What is Tuberculosis (TB): Causes, Symptoms, and Treatment?

Tuberculosis is a serious bacterial infection that primarily affects the lungs. Learn about transmission, symptoms, diagnosis, prevention, and treatment.

Infectious Diseases

Tuberculosis (TB): Causes, Symptoms, and Treatment

publishDate: 2025-09-04

Overview

Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis. It most often affects the lungs (pulmonary TB), but it can also spread to other organs (extrapulmonary TB).

TB is one of the world’s oldest and deadliest infectious diseases. Despite effective treatments, it remains a major global health problem, causing more than a million deaths each year. Drug resistance and gaps in healthcare access make TB control an ongoing challenge.

Key Points

TB spreads through the air when a person with active pulmonary TB coughs, sneezes, or speaks.
About a quarter of the world’s population carries latent TB infection, but most will never develop active disease.
Symptoms include a persistent cough, weight loss, fever, and night sweats.
Treatment requires multiple antibiotics over 6+ months.
Drug-resistant TB is a growing concern worldwide.
Vaccination with BCG offers partial protection, especially for infants and young children.

Symptoms

Persistent cough lasting more than 2–3 weeks
Coughing up blood (hemoptysis)
Chest pain or difficulty breathing
Unexplained weight loss
Night sweats and fever
Fatigue and weakness

Extrapulmonary TB can affect the lymph nodes, spine, kidneys, or brain, leading to a wide variety of symptoms.

Diagnosis

Tuberculin skin test (Mantoux test): measures immune response to TB proteins.
Interferon-gamma release assays (IGRAs): blood tests for TB infection.
Chest X-ray: to detect lung damage or active disease.
Sputum smear and culture: to confirm the presence of M. tuberculosis.
Molecular tests (GeneXpert): rapid detection, including drug resistance.

Treatment

First-line therapy: A combination of antibiotics (isoniazid, rifampin, pyrazinamide, ethambutol) for at least 6 months.
Drug-resistant TB (MDR-TB, XDR-TB): Requires longer treatment with second-line drugs, often less effective and with more side effects.
Directly Observed Therapy (DOT): Public health strategy where patients take medication under supervision to ensure adherence.

Prevention

BCG vaccine: Provides protection against severe childhood TB but limited protection against adult pulmonary TB.
Infection control: Masks, ventilation, and isolation in healthcare settings reduce spread.
Treatment of latent TB infection: Prevents progression to active disease, especially in high-risk individuals.

Recent Developments

Research into new TB vaccines and shorter drug regimens is ongoing.
The COVID-19 pandemic disrupted TB control programs worldwide, leading to increases in cases and deaths.
WHO aims to reduce global TB incidence and deaths significantly by 2030 as part of the “End TB Strategy.”

FAQ

Q: Can TB be cured?
A: Yes. With proper antibiotics taken for the full course, most cases of TB are curable.

Q: What is latent TB?
A: Latent TB means a person carries the bacteria but has no symptoms and cannot spread it. They remain at risk of developing active TB later.

Q: Why does TB treatment take so long?
A: The bacteria grow slowly and can hide in the body, requiring prolonged therapy to prevent relapse and resistance.

Q: Is TB only a problem in poor countries?
A: No. While most cases occur in low- and middle-income countries, TB also affects vulnerable populations in high-income countries.