Tuberculosis: Causes, Symptoms, Types & Tests

Tuberculosis, commonly known as TB, is a potentially serious infectious disease primarily affecting the lungs, but it can also spread to other organs such as the spine, brain, and kidneys. Caused by the bacterium Mycobacterium tuberculosis, TB spreads through airborne droplets when an infected person coughs, sneezes, or talks. Despite being preventable and treatable, TB remains a leading cause of death worldwide, especially in low- and middle-income countries. Understanding TB, its risk factors, symptoms, and testing options is crucial for early detection and control.

What is Tuberculosis?

Tuberculosis is an infectious disease characterized by the growth of nodules (tubercles) in the tissues, most commonly the lungs. When a person with active pulmonary TB expels bacteria into the air, those nearby may inhale them, leading to infection. After infection, TB bacteria can remain dormant in the body for years, a condition known as latent TB infection (LTBI). In some cases, the bacteria become active and multiply, causing active TB disease, which can be life-threatening without treatment.

Causes of Tuberculosis

TB is caused by the bacterium Mycobacterium tuberculosis. Factors that increase the risk of developing active TB include:

• Weakened immune system: Conditions like HIV/AIDS, diabetes, and certain cancers can reduce immunity.
• Malnutrition: Poor nutrition can lower the body’s defense against infections.
• Close contact: Living or working in close quarters with an infected person.
• Substance abuse: Alcohol and drug abuse can weaken immune response.
• Age: Very young children and elderly people have higher risk.
• Other medical treatments: Long-term use of corticosteroids or medications that suppress immunity.
• Travel or living in high-risk areas: TB is more common in regions like Africa, Asia, and Eastern Europe.

While TB is highly contagious in its active form, it typically requires prolonged exposure to spread.

Symptoms of Tuberculosis

Symptoms of TB vary depending on whether the infection is latent or active and which part of the body is affected.

Latent TB infection:

• No symptoms.
• Cannot spread to others.
• Detected through a TB skin test or blood test.

Active TB disease:
Common signs and symptoms include:

• Persistent cough lasting more than three weeks
• Coughing up blood or sputum (mucus)
• Chest pain, especially when breathing or coughing
• Unexplained weight loss
• Fatigue and weakness
• Fever and chills
• Night sweats
• Loss of appetite

TB can also affect organs other than the lungs, known as extra pulmonary TB, leading to symptoms like:

• Back pain (spinal TB)
• Swollen lymph nodes
• Joint pain
• Abdominal pain
• Neurological symptoms when the brain is affected

Types of Tuberculosis

TB is broadly categorized based on the nature of infection and the part of the body affected:

1. Latent TB Infection (LTBI):

• Bacteria remain inactive.
• Person has no symptoms.
• Cannot transmit TB to others.
• May become active later, especially if immunity weakens.

2. Active TB Disease:

• Bacteria multiply and cause illness.
• Symptoms appear.
• Can spread to others.

Based on location, TB is also divided into:

• Pulmonary TB: Affects the lungs; most common and contagious form.
• Extra pulmonary TB: Affects other organs like lymph nodes, kidneys, bones, brain, and spine.
• Miliary TB: A rare but severe form where bacteria spread throughout the body via the bloodstream.

Tests Used to Diagnose Tuberculosis

Early diagnosis of TB is critical to prevent complications and transmission. Common tests include:

• Tuberculin skin test (TST): A small amount of TB protein (PPD) is injected under the skin; swelling indicates exposure.
• Interferon-gamma release assays (IGRAs): Blood tests like QuantiFERON-TB Gold that detect immune response to TB bacteria.
• Chest X-ray: Checks for lung damage, lesions, or fluid accumulation.
• Sputum smear microscopy: Examination of sputum under a microscope to detect TB bacteria.
• Sputum culture: Culturing bacteria from sputum; takes weeks but confirms diagnosis and detects drug resistance.
• Molecular tests (e.g., CBNAAT, GeneXpert): Quickly detect TB DNA and resistance to drugs like rifampicin.
• Biopsy: For extrapulmonary TB, tissue biopsy may be needed.
• CT scan or MRI: Detailed imaging to assess TB in organs like the brain or spine.

In high-risk populations or complex cases, doctors may recommend a combination of these tests.

Treatment and Management of Tuberculosis

Treating TB requires strict adherence to medical protocols:

• Standard TB treatment: A combination of antibiotics over at least six months. Common drugs include isoniazid, rifampicin, ethambutol, and pyrazinamide.
• Directly Observed Treatment, Short-course (DOTS): Ensures patients take medication regularly.
• Drug-resistant TB: Requires longer treatment (18–24 months) with second-line drugs, which may have more side effects.
• Latent TB: Treated with fewer antibiotics over a shorter period to prevent activation.

Patients should:

• Complete the entire treatment course, even if they feel better.
• Maintain proper nutrition and rest.
• Attend regular follow-up visits.

Early and complete treatment reduces the risk of drug resistance and spread to others.

Prevention of Tuberculosis

Key preventive measures include:

• Vaccination: Bacillus Calmette–Guérin (BCG) vaccine helps protect infants and young children.
• Prompt treatment: Identifying and treating active TB cases.
• Protective measures: Wearing masks, improving ventilation, and reducing overcrowding.
• Screening: Regular TB testing for high-risk groups (healthcare workers, immunocompromised patients).
• Latent TB treatment: Helps prevent progression to active disease.

Conclusion

Tuberculosis continues to be a major public health challenge, especially in developing countries. However, with timely diagnosis, effective treatment, and preventive strategies, TB is both preventable and curable. Recognizing the symptoms, understanding risk factors, and getting tested if exposed are essential steps to protect yourself and your community. Advances in molecular testing and drug therapies have made TB care more precise and effective, yet awareness and education remains key in fighting this age-old disease.

Frequently Asked Questions (FAQs)

What causes tuberculosis?
Tuberculosis is caused by the bacterium Mycobacterium tuberculosis.

Is TB contagious?
Yes, active pulmonary TB can spread through airborne droplets when an infected person coughs, sneezes, or talks.

What are the symptoms of tuberculosis?
Symptoms include chronic cough, chest pain, coughing up blood, fever, night sweats, fatigue, and weight loss.

How is TB diagnosed?
Through tests like the tuberculin skin test, IGRA blood tests, chest X-ray, sputum microscopy, culture, and molecular tests.

Can TB be cured?
Yes, with a complete course of antibiotics, TB is curable in most cases.

What is latent TB?
A condition where TB bacteria are present in the body but inactive, causing no symptoms and not being contagious.

Who is at higher risk for TB?
People with weakened immune systems, those living in high-prevalence areas, healthcare workers, smokers, and individuals with poor nutrition.

What happens if TB treatment is incomplete?
Incomplete treatment can lead to drug-resistant TB, which is harder and longer to treat.

How can TB be prevented?
Through vaccination, early diagnosis, proper treatment, and reducing exposure to infected individuals.

What is extra pulmonary TB?
TB that affects organs outside the lungs, such as the lymph nodes, brain, spine, or kidneys.