Tuberculosis
Overview
Tuberculosis (TB) is a contagious disease primarily affecting the lungs, caused by the bacterium Mycobacterium tuberculosis. It is one of the top 10 causes of death worldwide, despite being preventable and curable.
Etiology
Mycobacterium tuberculosis, the causative agent of tuberculosis, is an aerobic, non-motile, acid-fast bacterium. It is characterized by its slow growth rate and its ability to survive in a dormant state for extended periods within the host, contributing to its virulence and the chronic nature of TB infection.
Pathogenesis
Infection with Mycobacterium tuberculosis typically occurs through inhalation of airborne droplets containing the bacteria. Once inhaled, the bacteria are engulfed by alveolar macrophages in the lungs, where they can survive and multiply, leading to the formation of a granulomatous lesion known as a tubercle.
Clinical Manifestations
Tuberculosis can be either latent or active. Latent TB infection (LTBI) is characterized by a positive reaction to the tuberculin skin test or interferon gamma release assay, but without clinical symptoms or evidence of active disease on chest radiography. Active TB disease, on the other hand, is characterized by symptoms such as persistent cough, fever, night sweats, weight loss, and radiographic evidence of pulmonary disease.
Diagnosis
Diagnosis of tuberculosis involves a combination of clinical evaluation, radiological imaging, microbiological testing, and immunological tests. The gold standard for TB diagnosis is the culture of Mycobacterium tuberculosis from sputum or other clinical specimens.
Treatment
Treatment of tuberculosis involves a combination of several antibiotics over a period of at least six months. The most commonly used drugs are Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol.
Prevention
Prevention strategies for tuberculosis include vaccination with the BCG vaccine, treatment of latent TB infection, and infection control measures in healthcare settings.
Epidemiology
Tuberculosis is a global health problem, with an estimated 10 million people developing active TB disease and 1.4 million deaths from TB in 2019. The highest burden of disease is in low- and middle-income countries, particularly in Africa and Southeast Asia.