What is tb disease

Definition and Cause

Tuberculosis (TB) is a serious infectious disease caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs but can affect other organs including the kidneys, spine, and brain. TB has affected humanity for thousands of years and remains a significant global health threat, particularly in developing nations with limited healthcare access and resources.

Transmission

TB spreads through airborne droplets when an infected person coughs, sneezes, speaks, or sings. Close, prolonged contact with an infected person increases transmission risk. TB is not spread through handshakes, shared food, or contaminated surfaces. People with untreated TB are most contagious, particularly in the first weeks of infection. Proper ventilation and respiratory precautions can reduce transmission risk significantly.

Types of TB

Pulmonary TB affects the lungs and is the most common form, accounting for approximately 80-85% of TB cases. Extrapulmonary TB affects organs outside the lungs, including bones, lymph nodes, and the central nervous system. Latent TB infection occurs when a person carries the bacteria but shows no symptoms and cannot transmit the disease. Approximately 25% of latent TB infections progress to active disease if untreated.

Symptoms and Diagnosis

Symptoms of active TB include persistent cough lasting more than three weeks, chest pain, fever, night sweats, and weight loss. Diagnosis involves chest X-rays, sputum tests, and tuberculin skin tests. Blood tests like the interferon-gamma release assay can detect both latent and active TB infection. Early diagnosis is crucial for effective treatment and preventing transmission.

Treatment and Prevention

TB is curable with a combination of at least four antibiotics taken for 6-9 months, depending on the type and severity. Adherence to the full treatment course is essential to prevent drug-resistant TB. Prevention includes vaccination with BCG in endemic areas, testing contacts of infected individuals, and treating latent TB infection. Public health measures include isolation of infectious patients and contact tracing.