Tuberculosis (TB)

Tuberculosis (TB)

Pulmonary tuberculosis (TB) is an infectious bacterial disease affecting the lungs, with potential spread to other organs.

Causes, Incidence, and Risk Factors

The bacterium Mycobacterium tuberculosis (M. tuberculosis) causes pulmonary tuberculosis (TB). Transmission occurs through inhalation of air droplets from coughs or sneezes of infected individuals, termed primary TB.

In the United States, most people recover from primary TB without further symptoms, as the infection may remain inactive (dormant) for years. However, in some cases, it may reactivate.

Certain populations are at higher risk for active TB, including the elderly, infants, and those with weakened immune systems due to conditions like AIDS, chemotherapy, diabetes, or certain medications.

Factors increasing the risk of TB transmission include frequent contact with infected individuals, poor nutrition, and crowded or unsanitary living conditions.

Contributing factors to TB infection rates in a population include rising HIV infections, homelessness, and the emergence of drug-resistant TB strains.

In Singapore, the incidence is approximately 72 per 100,000 population.

Symptoms

Primary TB typically presents without symptoms. Symptoms of pulmonary TB may include:

• Coughing (often with mucus)
• Coughing up blood
• Night sweats
• Fatigue
• Fever
• Unintentional weight loss

Additional symptoms may include breathing difficulty, chest pain, and wheezing.

Signs and Tests

Physical examination may reveal clubbing of fingers or toes, swollen lymph nodes, fluid around the lungs, and abnormal breath sounds.

Diagnostic tests may include tissue biopsy, bronchoscopy, chest CT scan, chest x-ray, interferon-gamma blood tests, sputum examination, thoracentesis, and tuberculin skin tests.

Treatment

The objective of treatment is to cure the infection using anti-TB medications. Treatment typically involves a combination of drugs, continued until lab tests determine the most effective medications.

Commonly used drugs include isoniazid, rifampin, pyrazinamide, and ethambutol. Additional medications such as amikacin, ethionamide, moxifloxacin, para-aminosalicylic acid, and streptomycin may be prescribed.

Patients may need to take multiple pills at different times daily for six months or longer, adhering strictly to their healthcare provider's instructions.

Non-compliance with medication regimen can lead to drug-resistant TB, necessitating directly observed therapy, where healthcare providers ensure patients take their prescribed drugs.

Hospitalization may be required to prevent disease transmission until the patient is no longer contagious.

Healthcare providers are legally mandated to report TB cases to local health departments to ensure patients receive optimal care.

Expectations (Prognosis)

Symptoms typically improve within 2-3 weeks, but chest x-rays may show improvement later. Early diagnosis and prompt treatment yield an excellent prognosis for pulmonary TB.