Tuberculosis

Tuberculosis:

Causative Agent
Tuberculosis (TB) is caused by the bacterium Mycobacterium tuberculosis. This highly contagious pathogen primarily affects the lungs, though it can spread to other organs, including the kidneys, spine, and brain.

Definition
Tuberculosis is a chronic infectious disease that typically affects the respiratory system, but in severe cases, it can involve other organs. TB is spread through airborne droplets when an infected person coughs or sneezes, making it highly contagious in close-contact environments.

Types of Tuberculosis

1. Pulmonary TB: The most common form, affecting the lungs.
2. Extrapulmonary TB: Involves other parts of the body such as the lymph nodes, kidneys, bones, or meninges (membranes surrounding the brain).
3. Latent TB: The bacteria are present in the body but are inactive, causing no symptoms. However, it can reactivate and turn into active TB if the immune system weakens.
4. Active TB: The bacteria are active and multiplying, leading to symptoms and making the individual contagious.

Etiopathogenesis
The disease is caused by inhaling M. tuberculosis droplets, which enter the lungs and may reach the alveoli. The immune system typically responds by forming granulomas—structures where immune cells try to contain the infection. However, if the immune response fails, the bacteria multiply, causing lung tissue damage and forming caseous necrosis (cheese-like material). The infection can either remain localized in the lungs (pulmonary TB) or spread via the bloodstream or lymphatic system (extrapulmonary TB).

Factors contributing to the development of TB include:

• Weakened immune system: HIV infection, diabetes, and malnutrition can lower immunity, increasing TB susceptibility.
• Close contact with infected individuals: Living in crowded or poorly ventilated areas.
• Drug-resistant strains: Multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) complicate treatment, making eradication harder.

Manifestations
Symptoms of active TB may include:

• Persistent cough lasting more than three weeks
• Coughing up blood or sputum (mucus)
• Chest pain, especially when breathing or coughing
• Unintentional weight loss
• Fever and night sweats
• Fatigue and weakness
• Loss of appetite
• Shortness of breath in advanced cases

For extrapulmonary TB, symptoms vary based on the affected organ:

• Lymph nodes: Swelling or pain in the neck.
• Bones and joints: Pain or reduced mobility.
• Brain (TB meningitis): Headache, confusion, and neck stiffness.
• Kidneys: Blood in urine or pain in the lower back.

Diagnosis
Diagnosis of TB involves a combination of clinical evaluation, imaging, and laboratory tests:

• Tuberculin skin test (Mantoux test): A small amount of tuberculin is injected under the skin, and the reaction is measured after 48-72 hours. A raised, hard area indicates TB exposure.
• Interferon-gamma release assays (IGRAs): Blood tests that measure immune response to TB bacteria.
• Chest X-ray: Detects lung abnormalities typical of TB.
• Sputum test: Microscopy or culture of sputum samples to detect M. tuberculosis.
• GeneXpert test: A rapid molecular test that detects TB bacteria and resistance to the drug rifampicin.

Treatment
Treatment of tuberculosis typically involves a prolonged course of antibiotics, as TB bacteria are slow-growing and can develop drug resistance.

Non-pharmacological treatment:

• Adequate nutrition: A well-balanced diet rich in vitamins and minerals can help boost the immune system and improve recovery.
• Isolation during the infectious period: To prevent transmission, TB patients should isolate, especially during the early stages of treatment, when they are most contagious.
• Rest and monitoring: Regular medical follow-up is essential to ensure the effectiveness of the treatment and to adjust the regimen if needed.

Pharmacological treatment:
The standard course for active TB typically lasts 6 to 9 months and involves a combination of antibiotics:

1. First-line drugs: The initial treatment includes a combination of isoniazid, rifampicin, pyrazinamide, and ethambutol for the first two months, followed by isoniazid and rifampicin for the remaining duration.
2. Second-line drugs: In cases of drug-resistant TB, fluoroquinolones, aminoglycosides, or other reserve antibiotics are used.
3. Directly observed therapy (DOT): In DOT, a healthcare provider observes the patient taking their medication to ensure adherence, which is crucial for preventing drug resistance.

Tips to Prevent Tuberculosis

• Vaccination: The Bacillus Calmette-Guérin (BCG) vaccine offers protection against TB, particularly in children. It is widely administered in high-burden countries.
• Improve ventilation: Since TB is airborne, ensuring proper ventilation in homes, workplaces, and public spaces can reduce transmission.
• Maintain good hygiene: Covering the mouth and nose while coughing or sneezing can prevent the spread of TB bacteria.
• Regular health check-ups: Especially for high-risk individuals, early detection through screening and testing is essential.
• Strengthen immunity: A healthy lifestyle that includes a balanced diet, regular exercise, and avoiding excessive alcohol consumption helps boost the immune system and reduces the risk of developing active TB.
• Complete TB treatment: If diagnosed, completing the full course of antibiotics is critical to prevent the spread of drug-resistant TB.

By following these preventive strategies and ensuring timely diagnosis and treatment, TB can be controlled and its spread minimized.

FAQs on Tuberculosis (TB)

1. What is tuberculosis (TB)?
Tuberculosis (TB) is a contagious bacterial infection caused by Mycobacterium tuberculosis, primarily affecting the lungs but can also spread to other parts of the body.

2. How is TB transmitted?
TB is spread through airborne droplets when an infected person coughs, sneezes, or talks, allowing the bacteria to be inhaled by others nearby.

3. What are the symptoms of TB?
Common symptoms include a persistent cough lasting more than three weeks, chest pain, weight loss, fever, night sweats, and coughing up blood.

4. How is TB diagnosed?
TB is diagnosed through a combination of a tuberculin skin test (Mantoux test), blood tests, chest X-rays, and sputum analysis to detect the presence of TB bacteria.

5. How is TB treated?
TB is treated with a combination of antibiotics taken for at least six months, with the most commonly used drugs being isoniazid, rifampicin, ethambutol, and pyrazinamide.

6. Can TB be prevented?
TB prevention includes vaccination with the BCG vaccine, avoiding close contact with infected individuals, and taking preventive medications if exposed to the bacteria.

7. What happens if TB is left untreated?
If left untreated, TB can lead to severe lung damage, spread to other organs, and may be fatal, while also posing a risk of spreading to others.