Tuberculosis (TB)

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Causes

1. Mycobacterium tuberculosis:–

• The primary cause of TB is infection with the bacterium Mycobacterium tuberculosis.

• Rationale:- Mycobacterium tuberculosis is a highly resilient bacterium capable of surviving within the human body for extended periods. It is transmitted via airborne droplets, making it highly infectious.

2. Close Contact with Infected Individuals:-

• TB is spread through close contact with individuals who have active pulmonary TB, as they expel the bacteria into the air when they cough or sneeze.

• Rationale:- Prolonged exposure to an individual with active TB, especially in closed environments, increases the risk of inhaling infectious droplets.

3. Weakened Immune System:-

• Individuals with a weakened immune system, such as those with HIV/AIDS, malnutrition, or undergoing immunosuppressive therapy, are at higher risk of developing TB.

• Rationale:- A weakened immune system is less capable of containing the TB bacteria within granulomas, leading to a higher risk of active disease.

4. Living in or Traveling to High-Risk Areas:-

• TB is more common in certain parts of the world, such as sub-Saharan Africa, Southeast Asia, and parts of Eastern Europe.

• Rationale:- In areas with high TB prevalence, the likelihood of encountering someone with active TB is higher, increasing the risk of infection.

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Clinical Manifestations 

1. Persistent Cough:-

• Definition:- A continuous cough lasting more than three weeks is a common symptom of pulmonary TB.

• Rationale:- In pulmonary TB, the bacteria cause inflammation and damage to the lung tissue, leading to a persistent cough. The cough is often productive (produces sputum) because of the body’s attempts to clear the infected material.

2. Hemoptysis (Coughing Up Blood):-

• Definition:- Hemoptysis is the coughing up of blood or blood-stained sputum, which can occur in advanced TB.

• Rationale:- The erosion of blood vessels by the infection in the lungs can cause bleeding, leading to the presence of blood in the sputum.

3. Night Sweats:-

• Definition:- Night sweats are episodes of excessive sweating during the night, often soaking bedclothes and sheets.

• Rationale:- Night sweats are a classic symptom of TB and are due to the body’s attempt to regulate its temperature in response to chronic infection.

4. Fever:-

• Definition:- Fever is a common symptom of TB and can be low-grade or high, depending on the severity of the infection.

• Rationale:- The body’s immune response to the TB bacteria includes raising the body’s temperature to help fight the infection.

5. Weight Loss:-

• Definition:- Unexplained weight loss is a hallmark symptom of TB, often referred to as “consumption.”

• Rationale:- TB is a chronic wasting disease. The body’s metabolic demands increase due to the ongoing infection, and appetite is often reduced, leading to significant weight loss.

6. Fatigue:-

• Definition:-Fatigue is extreme tiredness or lack of energy that is not relieved by rest.

• Rationale:- The chronic nature of TB and the body’s constant fight against the infection lead to persistent fatigue.

7. Chest Pain:-

• Definition:- Chest pain, often pleuritic (sharp and worsened by breathing), can occur in TB due to infection and inflammation in the lungs.

• Rationale:- The infection and resulting inflammation can irritate the pleura, and the lining around the lungs, causing chest pain.

8. Shortness of Breath (Dyspnea):-

• Definition:- Shortness of breath or difficulty breathing may occur in advanced TB when the lung tissue is extensively affected.

• Rationale:- Extensive lung involvement by TB can reduce lung capacity, making it difficult for the patient to breathe normally.

Lymphadenopathy:-

• • Rationale:- In extrapulmonary TB, especially TB lymphadenitis, lymph nodes become swollen, often in the neck region (scrofula).

Pleural Effusion:-

• • Rationale:- TB can cause an accumulation of fluid in the pleural space (the space between the lungs and chest wall), leading to pleural effusion, which can cause chest pain and difficulty breathing.

Meningitis Symptoms (in TB Meningitis):-

• • Rationale:- TB meningitis can cause symptoms like headache, neck stiffness, vomiting, altered mental status, and cranial nerve deficits due to inflammation of the meninges (the protective membranes covering the brain and spinal cord).

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Diagnostic Tests

Diagnosis of TB involves a combination of clinical evaluation, imaging, microbiological testing, and molecular diagnostics.

1. Tuberculin Skin Test (TST) or Mantoux Test:-

• Procedure:- A small amount (0.1 mL) of purified protein derivative (PPD) is injected intradermally, usually on the forearm. The injection site is examined 48-72 hours later for induration (a raised, hardened area).

• Normal Values:-

  • Induration > 15 mm: Positive for TB in any individual.

  • Induration > 10 mm: Positive in high-risk groups (e.g., recent immigrants, IV drug users).

  • Induration > 5 mm: Positive in immunocompromised individuals (e.g., HIV-positive patients).

• In BCG Vaccinated person will have a positive Mantoux test so evaluated with a chest X-ray

• Rationale:- A positive test indicates TB infection, but it cannot differentiate between latent TB and active disease. (after a positive Mantoux test A chest x-ray is important to rule out active TB or old TB scars or lesions)

2. Interferon-Gamma Release Assays (IGRAs):-

• Types:- QuantiFERON-TB Gold, T-SPOT.TB.

• Procedure:- A blood sample is taken, and the patient’s T-cells are exposed to TB antigens. The amount of interferon-gamma released is measured.

• Normal Values:- Negative test (no significant release of interferon-gamma).

• Rationale:- Useful in detecting latent TB infection, especially in individuals who have been vaccinated with Bacillus Calmette-Guérin (BCG), as it does not cross-react with the BCG vaccine.

3. Chest X-ray:-

• Findings:-

  • Pulmonary TB:- Infiltrates, nodules, consolidation, cavitation, and hilar lymphadenopathy.

  • Miliary TB:- Diffuse, small nodular opacities throughout the lung fields.

• Normal Values:- Clear lung fields, no abnormalities.

• Rationale:- Chest X-ray helps in identifying pulmonary TB, the extent of the disease, and monitoring treatment response. However, it cannot confirm TB, as similar findings can occur in other diseases.

4. Sputum Smear Microscopy:-

• Procedure:- Sputum samples are stained with Ziehl-Neelsen stain technique and examined under a microscope for acid-fast bacilli (AFB).

• Normal Values:- No AFB detected.

• Rationale:- A quick, inexpensive method for diagnosing pulmonary TB, particularly in resource-limited settings. However, it is less sensitive than culture or molecular tests.

5. Sputum Culture:-

• Procedure:- Sputum samples are cultured on specific media (Lowenstein-Jensen or Middlebrook) to grow M. tuberculosis. The process can take several weeks.

• Normal Values:- No growth of M. tuberculosis.

• Rationale:- Culture is the gold standard for TB diagnosis, as it allows for bacterial identification and drug susceptibility testing. 2 to 3 weeks after the medication starts again a sputum culture is to check the effectiveness of treatment, most sputum cultures are negative after 3 months of starting treatment

6. Nucleic Acid Amplification Tests (NAATs) and CBNAAT (Cartridge-Based Nucleic Acid Amplification Test):-

• Procedure:- Molecular tests that detect the DNA of M. tuberculosis directly from sputum or other samples.

• Normal Values:- No TB DNA detected.

• Rationale:- Provides rapid diagnosis and can also detect resistance to rifampicin, a key TB drug.

7. Lumbar Puncture (for TB Meningitis):-

• Procedure:- Cerebrospinal fluid (CSF) is obtained via lumbar puncture and analyzed.

• Findings:- Elevated protein, low glucose, and presence of AFB in the CSF.

• Normal Values:- Clear CSF with normal glucose and protein levels.

• Rationale:- Essential for diagnosing TB meningitis, which can be life-threatening without prompt treatment.

8. Biopsy:-

• Procedure:- Tissue samples from affected sites (e.g., lymph nodes, lung) are obtained and examined histologically for granulomas and AFB.

• Normal Values:- Absence of granulomas or AFB.

• Rationale:- Useful in diagnosing extrapulmonary TB, where direct sputum examination may not be possible.

How to Take Samples:-

• Sputum Collection:- The patient should collect an early morning sputum sample, preferably after rinsing their mouth with water. The sample should be expectorated into a sterile container.

• Precautions:- Ensure the sample is collected in a well-ventilated area or under negative pressure to avoid airborne transmission. The sample must be sent to the lab immediately or refrigerated if there is a delay.

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Management 

Management of tuberculosis (TB) involves a comprehensive approach that includes non-pharmacological, pharmacological, and surgical interventions. The goal is to cure the disease, prevent transmission, and reduce morbidity and mortality.

Non-Pharmacological Management

Non-pharmacological measures are essential in managing TB, particularly in preventing transmission and supporting the patient during treatment.

1. Isolation:-

   • Rationale:- Patients with active TB, especially those with pulmonary TB, should be isolated in a well-ventilated room to prevent the spread of M. tuberculosis to others. Isolation is particularly crucial during the initial phase of treatment when the patient is most infectious.

2. Negative Pressure Room:-

   A negative pressure room is a special hospital room designed to prevent the spread of airborne infections like tuberculosis (TB). It maintains lower air pressure inside, ensuring that air flows into the room rather than escaping, keeping pathogens contained.

   Purpose:-

   • To prevent the spread of airborne pathogens, including Mycobacterium tuberculosis.

   Mechanism:-

   • Air Pressure:-
     Maintains a pressure lower than surrounding areas, ensuring air flows into the room rather than escaping.

   • Air Entry:-
     Air enters through vents, ensuring good ventilation.

   • Air Exit:-
     Air exits through exhaust vents or filters, often with HEPA filters to capture infectious particles.

   • Maintenance:-

     • Ventilation Rate: Typically 6-12 air changes per hour.

     • Monitoring: Continuous pressure monitoring to ensure proper negative pressure.

     • Maintenance: Regular checks and maintenance of ventilation and filtration systems.

3. Nutritional Support:-

   • Rationale:- TB is a wasting disease, and malnutrition can exacerbate the condition. A balanced diet rich in calories, protein, vitamins (especially vitamin D), and minerals is necessary to support the immune system and improve treatment outcomes.

   • Vitamin D plays a role in immune function and may enhance the body’s ability to fight TB.

4. Education and Counseling:-

   • Rationale:- Educating patients and their families about TB, its transmission, the importance of adherence to treatment, and the potential side effects of medication is crucial.

   • Counseling can help address stigma, and mental health issues, and improve treatment adherence.

5. Respiratory Hygiene and Cough Etiquette:-

   • Rationale:- Patients should be taught to cover their mouths and noses when coughing or sneezing, preferably with a tissue, and to dispose of the tissue properly. This practice reduces the risk of spreading infectious droplets.

6. Ventilation:-

   • Rationale:- Good ventilation in living spaces reduces the concentration of airborne M. tuberculosis bacteria, decreasing the risk of transmission to others.

7. Regular Monitoring and Follow-up:-

   • Rationale:- Regular monitoring of the patient’s response to treatment is necessary to detect any complications early, assess adherence, and modify treatment if necessary.

   • Follow-up also ensures that any side effects from the medication are managed promptly.

Pharmacological Management of Tuberculosis (TB)

TB treatment involves using multiple drugs to kill the bacteria and prevent resistance. Duration depends on TB type.

• Latent Tuberculosis (LTBI):- TB bacteria are present in the body but inactive and not causing symptoms. The person is not contagious. ( given prophylaxis treatment)

• Active Tuberculosis (TB):- TB bacteria are actively growing, causing symptoms, and the person can spread the disease to others.

DOTS (Directly Observed Treatment, Short-course):-

• DOTS is the WHO-recommended treatment approach for TB, involving direct observation of patients taking their medications to ensure adherence.

• This method prevents drug resistance, ensures proper drug intake, and improves cure rates.

• It includes a standardized treatment regimen, patient monitoring, direct observation, and consistent drug supply.

• By ensuring that TB medications are taken correctly, DOTS helps prevent the development of multi-drug-resistant TB (MDR-TB).

1. First-Line Anti-TB Drugs:-

These drugs are the cornerstone of TB treatment, used primarily for drug-susceptible TB.

• Isoniazid (INH):-

  • Action:- Bactericidal; inhibits the synthesis of mycolic acids, essential components of the bacterial cell wall.

  • Reason for Use:- Highly effective against actively dividing TB bacteria.

  • Dosage:-

    • Latent TB:- 300 mg daily for 6-9 months.

    • Active TB:- 5 mg/kg daily (max 300 mg) for 6 months.

  • Complications/Side Effects:- Hepatotoxicity, peripheral neuropathy (prevented with pyridoxine [vitamin B6]), rash, fatigue.

• Rifampin (RIF):-

  • Action:- Bactericidal; inhibits bacterial RNA polymerase, preventing RNA synthesis and bacterial replication.

  • Reason for Use:- Effective against rapidly multiplying TB bacteria.

  • Dosage:-

    • Latent TB:- 600 mg daily for 4 months.

    • Active TB:- 10 mg/kg daily (max 600 mg) for 6 months.

  • Complications/Side Effects:- Hepatotoxicity, orange discoloration of body fluids, flu-like symptoms, drug interactions (induces cytochrome P450 enzymes).

• Pyrazinamide (PZA):-

  • Action:- Bactericidal; disrupts membrane transport and energy production in TB bacteria.

  • Reason for Use:- Effective in acidic environments like those found in macrophages and TB lesions.

  • Dosage:- 15-30 mg/kg daily (max 2 g) for the initial 2 months of treatment.

  • Complications/Side Effects:- Hepatotoxicity, hyperuricemia (can lead to gout), arthralgia.

• Ethambutol (EMB):-

  • Action:- Bacteriostatic; inhibits arabinosyl transferase, disrupting cell wall synthesis.

  • Reason for Use:- Prevents the emergence of drug resistance, especially to INH and RIF.

  • Dosage:- 15-25 mg/kg daily (max 1.6 g) for 6 months.

  • Complications/Side Effects:- Optic neuritis (dose-related, reversible), visual disturbances, color blindness.

• Streptomycin ( Removed from first-line drug):-

  Mechanism of Action:-

  • Action:- Streptomycin is a bactericidal aminoglycoside that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, killing Mycobacterium tuberculosis.

  Reason for Use:-

  • Severe TB Cases:- Historically used for severe TB, including TB meningitis.

  • Drug-Resistant TB:- Now used mainly in MDR-TB when other first-line drugs are ineffective.

  Dosage:-

  • Typical Dosage:- 15 mg/kg IM daily (up to 1 g/day) for 2-3 months, with possible continuation at 2-3 times per week.

  Complications/Side Effects:-

  • Ototoxicity:- Risk of irreversible hearing loss.

  • Nephrotoxicity:- Potential kidney damage.

  • Vestibular Toxicity:- Causes dizziness and balance issues.

  Why Streptomycin is Not Commonly Used:-

  1. Toxicity:- High risk of hearing loss and kidney damage.

  2. Injection Requirement:- IM administration is painful and inconvenient.

  3. Better Alternatives:- Oral drugs like ethambutol are safer and easier to use.

  4. Drug Resistance:- Streptomycin-resistant TB strains have emerged.

2. Second-Line Anti-TB Drugs:-

These drugs are used for multi-drug resistant TB (MDR-TB) or when first-line drugs are not effective or cannot be used.

• Levofloxacin:-

  • Action:- Bactericidal; inhibits bacterial DNA gyrase and topoisomerase IV, essential for DNA replication.

  • Reason for Use:- Effective against drug-resistant TB strains.

  • Dosage:- 750 mg daily (MDR-TB treatment can last 18-24 months).

  • Complications/Side Effects:- Tendonitis, tendon rupture, QT prolongation, gastrointestinal disturbances.

• Moxifloxacin:-

  • Action:- Bactericidal; similar to levofloxacin but with enhanced activity against TB.

  • Reason for Use:- Often used in MDR-TB regimens.

  • Dosage:- 400 mg daily (duration 18-24 months for MDR-TB).

  • Complications/Side Effects:- Similar to levofloxacin.

• Amikacin:-

  • Action:- Bactericidal; inhibits protein synthesis by binding to bacterial ribosomes.

  • Reason for Use:- Used in combination with other drugs for MDR-TB.

  • Dosage:- 15 mg/kg daily (duration varies).

  • Complications/Side Effects:- Nephrotoxicity, ototoxicity, vestibular toxicity.

• Bedaquiline:-

  • Action:- Bactericidal; inhibits ATP synthase in TB bacteria, disrupting energy production.

  • Reason for Use:- Specifically used for MDR-TB.

  • Dosage:- 400 mg daily for 2 weeks, then 200 mg three times per week for 24 weeks.

  • Complications/Side Effects:- QT prolongation, hepatotoxicity, nausea, headache.

• Linezolid:-

  • Action:- Bacteriostatic; inhibits protein synthesis by binding to bacterial ribosomes.

  • Reason for Use:- Reserved for MDR-TB, especially when other options are exhausted.

  • Dosage:- 600 mg daily (duration varies).

  • Complications/Side Effects:- Bone marrow suppression, peripheral neuropathy, optic neuropathy.

3. Treatment Regimens and Duration:-

• Latent TB Infection:-

  • Preferred Regimen:- INH daily for 6-9 months, or RIF daily for 4 months.

• Active Drug-Susceptible TB:-

  • Initial Phase (2 months):- INH, RIF, PZA, and EMB.

  • Continuation Phase (4 months):- INH and RIF.

  • Total Duration:- 6 months.

• MDR-TB (Multi-Drug Resistant TB):-

  • Regimen:- Includes second-line drugs like levofloxacin, moxifloxacin, bedaquiline, and linezolid.

  • Duration:- 18-24 months.

• XDR-TB (Extensively Drug-Resistant TB):-

  • Regimen:- Combination of second-line drugs, often including bedaquiline, linezolid, and clofazimine.

  • Duration:- At least 24 months.

• Rationale:- MDR-TB is resistant to at least isoniazid and rifampicin, while XDR-TB is resistant to first-line drugs and at least one second-line injectable drug.

• Treatment requires a longer duration (up to 20-24 months) and the use of second-line drugs, which are less effective, more toxic, and more expensive.

  • Normal Findings:- Negative sputum culture, improvement in clinical symptoms.

  • Complications:- Increased side effects, such as nephrotoxicity (with aminoglycosides), ototoxicity, and bone marrow suppression.

Surgical Management:-

Surgical interventions are considered in cases of complicated or resistant TB, or when pharmacological treatment alone is insufficient.

1. Lobectomy or Pneumonectomy:-

   • Procedure:- Surgical removal of a lobe (lobectomy) or the entire lung (pneumonectomy) affected by TB.

   • Indications:- Extensive cavitary TB, localized drug-resistant TB, or TB complicated by massive hemoptysis.

   • Rationale:- Removing the diseased lung tissue can help control the infection, reduce bacterial load, and prevent life-threatening complications like hemoptysis.

2. Pleural Drainage:-

   • Procedure:- In cases of TB pleurisy with a significant pleural effusion, drainage of the pleural fluid may be necessary.

   • Rationale:- Draining the fluid can relieve symptoms, prevent pleural thickening, and facilitate the diagnosis of TB by allowing analysis of the pleural fluid.

3. Lymph Node Excision:-

   • Procedure:- Surgical removal of affected lymph nodes in cases of TB lymphadenitis that do not respond to medical therapy.

   • Rationale:- Excision may be necessary for diagnostic purposes or to relieve symptoms if the lymph nodes cause compression of vital structures.

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Nursing Care 

1. Infection Control:-

• Explanation:- Implement airborne precautions for patients with suspected or confirmed TB. This includes placing the patient in a negative pressure room and requiring healthcare workers to wear N95 respirators.

• Rationale:- TB is highly contagious, and airborne precautions are necessary to prevent the spread of the infection to others.

2. Medication Administration and Adherence:-

• Explanation:- Administer anti-TB medications as prescribed and ensure that the patient understands the importance of completing the full course of treatment.

• Rationale:- Adherence to the medication regimen is critical to prevent the development of drug-resistant TB.

3. Nutritional Support:-

• Explanation:- Provide a high-calorie, high-protein diet to support the patient’s recovery and address weight loss associated with TB.

• Rationale:- Nutritional support is essential as TB can lead to significant weight loss and malnutrition, which can impair the immune response.

4. Respiratory Care:-

• Explanation:- Encourage deep breathing exercises and coughing to help clear secretions and improve lung function.

• Rationale:- Maintaining lung function is important in preventing complications such as pneumonia, which can occur due to reduced lung capacity in TB patients.

5. Education and Support:-

• Explanation:- Educate the patient and their family about TB transmission, the importance of medication adherence, and how to prevent the spread of the disease.

• Rationale:- Patient education is crucial in ensuring that the patient adheres to the treatment regimen and understands how to protect others from infection.

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2. Miliary Tuberculosis:-

   • Rationale:- Miliary TB occurs when Mycobacterium tuberculosis spreads through the bloodstream to multiple organs, forming tiny nodules in tissues. This form of TB affects the liver, spleen, bone marrow, and central nervous system.

3. Pleural Effusion and Empyema:-

   • Rationale:- TB can cause pleural effusion (fluid accumulation in the pleural space) or empyema (pus in the pleural space), leading to chest pain, dyspnea, and fever. These complications may require pleural drainage and prolonged antibiotic therapy.

4. Tuberculous Meningitis:-

   • Rationale:- This is a severe complication where TB affects the meninges (the protective membranes covering the brain and spinal cord). Symptoms include headache, fever, neck stiffness, altered mental status, and seizures.

5. Spinal Tuberculosis (Pott’s Disease):-

   • Rationale:- TB can affect the spine, leading to vertebral destruction, spinal deformities, and neurological deficits due to spinal cord compression. Pott’s disease can cause chronic back pain, and paralysis, and may require surgical intervention to stabilize the spine.

6. Hepatotoxicity:-

   • Rationale:- Anti-TB drugs, particularly isoniazid, rifampicin, and pyrazinamide, can cause liver damage, leading to hepatotoxicity. This complication is characterized by elevated liver enzymes, jaundice, and in severe cases, liver failure. Regular monitoring of liver function is essential during TB treatment.

7. Optic Neuritis:-

   • Rationale:- Ethambutol, one of the first-line TB drugs, can cause optic neuritis, an inflammation of the optic nerve, leading to blurred vision, color blindness, and potential vision loss. This side effect is dose-dependent and reversible upon discontinuation of the drug.

8. Peripheral Neuropathy:-

   • Rationale:- Isoniazid can cause peripheral neuropathy, characterized by numbness, tingling, and pain in the hands and feet. This is due to the depletion of vitamin B6 (pyridoxine), which is why pyridoxine supplementation is recommended during treatment.

9. Renal Failure:-

   • Rationale:- TB can cause renal complications, including glomerulonephritis (inflammation of the kidneys) or obstructive uropathy due to granulomas in the renal tissue. Additionally, nephrotoxic drugs used in the treatment of drug-resistant TB can lead to acute or chronic renal failure.

10. Multi-Drug Resistant TB (MDR-TB) and Extensively Drug-Resistant TB (XDR-TB):-

    • Rationale:- Inadequate or incomplete treatment can lead to the development of drug-resistant TB strains. MDR-TB is resistant to at least isoniazid and rifampicin, while XDR-TB is resistant to second-line drugs as well. These forms of TB are more difficult to treat, require longer treatment durations, and have higher mortality rates.

11. Bronchiectasis:-

    • Rationale:- Chronic TB can lead to bronchiectasis, a condition where the bronchial tubes become permanently widened, leading to chronic cough, sputum production, and recurrent lung infections. This complication arises due to the destruction of lung tissue and scarring from the infection.

12. Pulmonary Hypertension:-

    • Rationale:- Chronic TB can lead to pulmonary hypertension, where the blood pressure in the lungs’ arteries increases due to lung damage and reduced oxygen levels. This condition can cause right heart failure (cor pulmonale) and is associated with poor prognosis.

13. Atelectasis:-

    • Rationale:- TB can cause collapse of a portion of the lung (atelectasis) due to obstruction of the airways by granulomas or fibrosis. This leads to reduced oxygenation, difficulty breathing, and increased risk of secondary infections.

14. Infertility:-

    • Rationale:- Genitourinary TB can affect the reproductive organs, leading to infertility, especially in women. TB can cause scarring and obstruction of the fallopian tubes, uterus, or ovaries, making it difficult for a woman to conceive.

15. Chronic Pulmonary Aspergillosis:-

    • Rationale:- Patients with TB, especially those with cavitary disease, are at risk of developing chronic pulmonary aspergillosis, a fungal infection that occurs in the damaged lung tissue. This condition can cause hemoptysis, weight loss, and fatigue, and may require antifungal treatment.

16. Social and Economic Impact:-

    • Rationale:- TB can have a profound social and economic impact on patients and their families. The disease often leads to prolonged periods of illness, loss of income, stigma, and discrimination, which can affect the patient’s quality of life and mental health.