Causes of Tuberculosis Explained
Understand the core causes of Tuberculosis (TB), primarily the Mycobacterium tuberculosis bacterium. Learn how it spreads, who is at risk, and the critical factors that contribute to TB infection and active disease development.
Written by Dr. Rohinipriyanka Pondugula
Reviewed by Dr. Shaik Abdul Kalam MD (Physician)
Last updated on 19th Aug, 2025
Tuberculosis (TB) is a serious infectious disease that primarily affects the lungs but can also impact other parts of the body. While TB can be treated and prevented, it remains a major health concern in many parts of the world. If you or someone you know has been diagnosed with TB, understanding its causes can help in taking the right precautions and seeking timely treatment.
In this article, we’ll explore the causes of tuberculosis, how it spreads, and what you can do to protect yourself and your loved ones.
What Causes Tuberculosis?
Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis. This germ primarily attacks the lungs but can also affect the kidneys, spine, brain, and other organs. Not everyone infected with TB bacteria becomes sick, which is why TB is classified into two types:
- Latent TB Infection (LTBI) – The bacteria remain inactive in the body, causing no symptoms and no spread to others.
- Active TB Disease – The bacteria multiply, leading to symptoms and the possibility of spreading the infection.
The main causes and risk factors that contribute to TB infection and progression include:
1. Bacterial Transmission (How TB Spreads)
TB spreads through the air when an infected person coughs, sneezes, speaks, or sings, releasing tiny droplets containing the bacteria. If another person inhales these droplets, they may get infected.
Key Points:
- TB is not spread by shaking hands, sharing food, or touching surfaces.
- Close and prolonged contact with an infected person increases the risk.
- Poorly ventilated spaces (like crowded homes or workplaces) raise transmission risks.
2. Weakened Immune System
A strong immune system can often keep TB bacteria in check, preventing active disease. However, certain conditions weaken immunity, increasing the risk of active TB:
- HIV/AIDS – Weakens the immune system, making TB infection more likely.
- Diabetes – Poorly controlled diabetes increases susceptibility.
- Chronic Diseases – Conditions like kidney disease, cancer, or malnutrition lower immunity.
- Medications – Long-term use of steroids or immunosuppressive drugs (e.g., for autoimmune diseases) can increase TB risk.
3. Lifestyle and Environmental Factors
Certain living conditions and habits can contribute to TB infection:
- Malnutrition – Poor diet weakens the body’s defenses.
- Smoking & Alcohol Abuse – Damages lung health and immunity.
- Overcrowded Living Conditions – Increases exposure to TB bacteria.
- Lack of Healthcare Access – Delayed diagnosis and treatment allow TB to spread.
4. Previous TB Infection or Incomplete Treatment
People who have had TB before or did not complete their full course of treatment are at higher risk of:
- TB Reactivation – Latent TB can become active if immunity drops.
- Drug-Resistant TB – Stopping treatment early can lead to antibiotic-resistant strains.
Consult Top Specialists
How Does TB Affect Your Health?
If TB bacteria become active, they can cause symptoms such as:
- Persistent cough (lasting 3+ weeks)
- Coughing up blood or mucus
- Chest pain
- Fatigue and weakness
- Fever and night sweats
- Unintended weight loss
Without treatment, TB can damage the lungs and spread to other organs, leading to severe complications.
How Can You Protect Yourself from TB?
While TB is contagious, there are ways to reduce your risk:
1. Get Tested if You Have Symptoms or Exposure
If you’ve been in close contact with a TB patient or have symptoms, consult a doctor. Tests include:
- Tuberculin Skin Test (TST)
- Blood Test (IGRA)
- Chest X-ray & Sputum Test
2. Complete TB Treatment if Diagnosed
TB is curable with antibiotics, but treatment must be taken exactly as prescribed (usually 6–9 months). Stopping early can lead to drug resistance.
3. Strengthen Your Immune System
- Eat a balanced diet rich in vitamins and proteins.
- Exercise regularly and avoid smoking/alcohol.
- Manage chronic conditions like diabetes properly.
4. Practice Good Hygiene
- Cover your mouth when coughing/sneezing.
- Ensure proper ventilation at home and workplace.
- Avoid close contact with active TB patients unless necessary.
5. Consider BCG Vaccination (For HighRisk Groups)
The BCG vaccine (given in childhood in some countries) offers partial protection against severe TB forms.
When to See a Doctor?
If you experience:
- A cough lasting more than 3 weeks
- Unexplained weight loss
- Night sweats or prolonged fever
Consult a healthcare provider immediately. Early diagnosis and treatment prevent complications and stop the spread.
Need Help? Book a Consultation Today
If you suspect TB exposure or have symptoms, don’t wait. Apollo 24|7 offers expert consultations and diagnostic tests for TB. You can:
- Book a doctor’s appointment online.
- Schedule a TB test for quick and accurate diagnosis.
Taking prompt action can protect you and those around you. Stay informed, stay safe!
Final Thoughts
Tuberculosis is caused by bacterial infection, weakened immunity, and environmental factors. While it can be serious, proper treatment and preventive measures can control its spread. If you have concerns about TB, reach out to a healthcare professional for guidance.
Stay healthy, stay protected!
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Consult Top Specialists
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Consult Top Specialists
Dr. Mohamed Azeem
General Physician/ Internal Medicine Specialist
2 Years • MBBS,MD(Internal Medicine) CCEBDM
Karaikudi
Apollo Hospitals Karaikudi, Karaikudi
Dr. Aakash Garg
Gastroenterology/gi Medicine Specialist
12 Years • MBBS, DNB (Medicine), DrNB (Gastroentrology).
Bilaspur
Apollo Hospitals Seepat Road, Bilaspur
(125+ Patients)
Dr. Debashis Nayak
Endocrinologist
8 Years • MBBS, DNB (Internal Medicine), PG Diploma ( Diabetes & Endocrinology )
Rourkela
Apollo Hospitals, Rourkela, Rourkela
Dr. R Gopakumar
Internal Medicine/ Covid Consultation Specialist
31 Years • MBBS, MD(general medicine
Angamaly
Apollo Hospitals Karukutty, Angamaly
(25+ Patients)
Divyashree K
General Physician/ Internal Medicine Specialist
5 Years • MBBS
Bengaluru
Apollo Clinic, JP nagar, Bengaluru
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