Tuberculosis; types, risk factors, clinical features, management and prevention

Introduction

Tuberculosis (TB) is a chronic pulmonary and extra-pulmonary infectious disease caused by mycobacterium tuberculosis. The disease commonly affects the respiratory system but other parts of the body can also be affected for example TB of the skin, bones, uterus, joints, nervous system, lymph nodes and intestines etc.

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Incubation period: 4-12weeks (varies as long as bacilli are in sputum).

Types of Tuberculosis

    1. Extra-pulmonary TB (affecting any organ other than the lung tissue).e g bones, skins, uterus etc.

    2. Pulmonary Tuberculosis

This type of TB affects mainly the lung tissue.

Mode of transmission; through droplet infection - inhalation of the bacilli from an infected person who coughs, sneezes, spits, speaks or sings. The infectious person expels the bacilli into the air in tiny droplets. There are many types of tuberculosis but the human and bovine (cattle) ones are common, ingestion of contaminated milk or meat will lead to intestinal TB.

Risk factors

• Duration of exposures e.g. nurses, doctors and laboratory technicians who work in the TB ward. 
• HIV/AIDS patients.
• People with low immunity e.g. cancer patients
• Cigarette smokers and people who drink alcohol 
• Overcrowding.
• Patients who are on immunosuppressive drugs e.g. cancer drugs

Pathophysiology

When the bacilli are inhaled it establish in the lungs and begin to multiply. The bacilli invades the tissue at the portal of entry, usually the middle or lower zones of the lungs, creating a small inflammatory lesion leading to fever. Phagocytes invades the site and begin to destroy bacilli. Some however do escape destroying the phagocytes and surrounding tissue leaving some cavities. The necrotic tissue produced triggers the coughing. In addition, the bacilli gets into the blood resulting in sub-clinical bacteriaemia spreading the disease all over the body.

Clinical Features

1. Persistent cough for more than 2 weeks 
2. Haemoptysis 
3. Chest pain 
4. Dyspnoea (Difficulty in breathing) 
5. Night sweats 
6. Fever 
7. Anorexia (loss of appetite) 
8. Weight loss 
9. Fatigue 
10. Malaise 
11. Tachycardia

Diagnostic investigations

• Mantoux or Tuberculin skin sensitivity test (PPD test - purified protein derivative). 
• Microscopic examination of sputum. 
• Chest x-ray (shows cavitation(s) or calcified shadows). 
• Clinical presentation.

Management

The treatment of TB has gone through a lot of transition with implementation strategies over the years. Currently, treatment duration has been reduced to 6 months (category I) and maintained at 8 months (category II). The use of streptomycin for new cases has been curtailed. Rifampicin is used throughout the D.O.T.S strategy.

Regimen for TB is given to;

• cure the patient with TB. 
• prevent death from active diseases or its complications. 
• prevent TB relapse. 
• present TB transmission to others. 
• To prevent the development of resistant TB.

Medically, TB is managed with Anti-tuberculosis drugs;

• Pyrazinamide - Z 
• Rifampicin – R 
• Ethambutol – E 
• Isoniazid – H 
• Streptomycin – S

Some of the anti-TB drugs are combined into blisters to promote drug compliance.

Note: Streptomycin is given only for recurring cases or re-treatment, it is also oxytocic to the foetus hence the substitute drugs during pregnancy is Ethambutol. Pyrazinamide is not given to children. Thiacetazone is contra-indicated in HIV positive clients, the substitute drug is Ethambutol. Rifampicin can lower effect of oral contraceptives.

Nursing Management

• TB is communicable, Isolate the patient. 
• If there is dyspnea, nurse patient in upright position. 
• Check weight every day and record. 
• If there is cyanosis, oxygen can be administered. 
• Serve nutritious diet. 
• Patient education; advice patient to use handkerchief when sneezing or coughing to prevent spread. 
• Nurse in well ventilated room. 
• Serve prescribed medication, treatment should be under DOTS.

Prevention

• BCG immunization at birth. 
• Educate the people on the disease and the need for treatment compliance. 
• Prompt treatment of infected individuals. 
• Regular drug supple to ensure continuous treatment. 
• Avoid drinking raw or unpasteurized milk. 
• The mouth and nose should be covered when coughing or sneezing. 
• Cook meals properly and eat them warm.

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