Overview

Tuberculosis (TB) is a serious infectious disease caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs but can spread to other organs, such as the kidneys, brain, and spine. While TB is curable and preventable, it remains one of the top 10 causes of death worldwide. The disease spreads through the air when an infected person coughs, sneezes, speaks, or breathes heavily. Understanding TB's types, causes, symptoms, treatment options, and complications is essential for both prevention and early intervention.

Types of Tuberculosis

There are three primary classifications of TB:

  • Latent TB Infection (LTBI): In this form, the bacteria are present in the body but inactive. There are no symptoms, and it is not contagious. However, it can become active later, especially if the immune system weakens.

  • Active TB Disease: This occurs when the bacteria become active and multiply. It causes symptoms and can be transmitted to others. Immediate medical intervention is necessary.

  • Multidrug-Resistant TB (MDR-TB): MDR-TB resists the most potent TB drugs, making it difficult and longer to treat. It develops due to incomplete treatment or the use of improper medications.

Common Symptoms

Active TB disease presents with a variety of symptoms depending on the organs affected. Most commonly, TB affects the lungs (pulmonary TB):

  • Persistent cough lasting three weeks or longer

  • Coughing up blood or sputum

  • Chest pain

  • Fever and chills

  • Night sweats

  • Fatigue

  • Loss of appetite

  • Unintended weight loss

Extrapulmonary TB (TB in other organs) may cause:

  • Back pain (spinal TB)

  • Blood in urine (kidney TB)

  • Headaches or mental confusion (brain TB)

Latent TB has no symptoms.

Causes and Transmission

TB is caused by Mycobacterium tuberculosis, a slow-growing bacterium. It is transmitted via airborne particles. When someone with active pulmonary TB coughs or sneezes, they release tiny droplets containing the bacteria into the air. People nearby may inhale these droplets and become infected.

However, TB is not as contagious as the flu or cold. Close and prolonged contact with someone who has active TB is usually required for transmission. The disease is more common in areas with crowded living conditions, poor healthcare infrastructure, and high rates of HIV.

Risk Factors

Certain groups are more vulnerable to contracting TB or developing active TB from a latent infection:

  • People with weakened immune systems (HIV/AIDS, diabetes, cancer patients)

  • Young children and the elderly

  • People living in crowded or unsanitary conditions

  • Malnourished individuals

  • Smokers and those with substance use disorders

  • Healthcare workers exposed to TB patients

  • Travelers or residents of TB-endemic regions

Diagnosis

Diagnosing TB involves a combination of medical history, physical examination, and laboratory tests:

  • Tuberculin Skin Test (TST): Also called the Mantoux test, a small amount of TB protein is injected under the skin. A raised bump indicates exposure.

  • Blood Test (IGRA): Measures immune response to TB bacteria. It does not distinguish between active and latent TB.

  • Chest X-ray or CT Scan: Identifies abnormalities in the lungs.

  • Sputum Smear and Culture: Checks mucus from the lungs for TB bacteria.

  • Bronchoscopy and Biopsy: In difficult cases, these help diagnose TB in organs other than the lungs.

Treatment for TB

TB is treatable with a strict and prolonged course of antibiotics. The treatment depends on the type of TB:

Latent TB Infection:

  • Isoniazid (INH)

  • Rifampin (RIF)

  • Rifapentine (RPT)

Regimens may last 3 to 4 months and significantly reduce the risk of developing active TB.

Active TB Disease: Treatment typically involves a combination of at least four antibiotics taken for 6 to 9 months:

  • Isoniazid

  • Rifampin

  • Pyrazinamide

  • Ethambutol

After a few weeks of treatment, patients usually stop being contagious but must continue treatment to ensure the infection is fully cleared.

Multidrug-Resistant TB (MDR-TB): MDR-TB treatment is more complex and may last up to 20–30 months, requiring second-line drugs that can have more severe side effects.

Side Effects of Treatment

Common side effects of TB drugs include:

  • Nausea and vomiting

  • Loss of appetite

  • Liver toxicity

  • Orange discoloration of urine and tears

  • Rash

  • Numbness or tingling in hands or feet

For MDR-TB, side effects can include:

  • Hearing loss

  • Depression

  • Joint pain

  • Kidney damage

Regular monitoring by a healthcare provider is essential.

Managing TB Treatment

Strict adherence to the treatment regimen is critical. Skipping doses or stopping early can lead to drug resistance. Programs like Directly Observed Therapy (DOT) help ensure patients complete their course by having a healthcare provider supervise each dose.

Tools like medication reminder apps, blister packs, or treatment support groups may improve adherence and treatment outcomes.

Prevention

Preventing TB involves both medical and public health strategies:

  • Vaccination: The Bacillus Calmette-Guerin (BCG) vaccine is used in many countries but has limited efficacy in adults.

  • Early Detection and Treatment: Screening high-risk populations helps prevent disease progression.

  • Infection Control Measures: Proper ventilation, UV light sterilization, and personal protective equipment in healthcare settings reduce spread.

  • Isolation: Infected individuals should avoid public spaces until they are no longer contagious.

Complications

If left untreated, TB can lead to severe complications:

  • Permanent lung damage

  • Respiratory failure

  • Meningitis (brain inflammation)

  • Heart inflammation

  • Infertility (in cases of genital TB)

  • Spread to bones or spine

Co-infection with HIV significantly worsens the outcome. TB is the leading cause of death among people with HIV globally.

A Quick Review

Tuberculosis is a serious but treatable disease caused by Mycobacterium tuberculosis. It mainly affects the lungs but can damage other organs. With proper medical care, most cases of TB can be cured. The key is early detection, completing treatment, and reducing transmission through public health measures.

If you are at risk or experiencing symptoms, seek medical care promptly to avoid complications and protect others around you.