/AIDS create a perfect storm for its spread.
Transmission and Pathophysiology
TB is an airborne disease. The bacteria are aerosolized and released into the air when a
person with active pulmonary TB coughs, sneezes, or speaks. These tiny droplets, called
droplet nuclei, can remain suspended in the air for hours, and when inhaled by a new host,
they travel deep into the lungs.
The infection's progression can take two primary paths: latent TB infection (LTBI) or active
TB disease.
Latent TB Infection (LTBI): In most healthy individuals, the he d. Vrvrv r. R vrvrvrvr r r f t r t
tbr t f system is able to contain the M. tuberculosis bacteria. Macrophages and T-cells form a
protective barrier, a granuloma, around the bacteria, effectively walling them off. The person
with LTBI is asymptomatic and cannot transmit the disease. However, the bacteria remain
dormant within the granulomas, and a latent infection can reactivate into active disease later
in life if the person's immune system becomes compromised.
Active TB Disease: If the immune system is unable to contain the bacteria, they multiply and
cause active disease. In over 80% of cases, this disease is pulmonary TB, affecting the
lungs. The bacteria destroy lung tissue, leading to the formation of cavities and lesions. This
causes the characteristic symptoms of TB: a persistent cough (often with blood-tinged
sputum), chest pain, fever, night sweats, and unexplained weight loss. Beyond the lungs, TB
can also spread to other parts of the body, a condition known as extrapulmonary TB. This
can affect the lymph nodes, pleura, brain (tuberculous meningitis), bones (Pott's disease),
kidneys, and other organs, leading to a wide range of debilitating and often fatal
complications.
