50 year old, Rishi has a diagnosis of pulmonary tuberculosis. How many infectious nuclei per cough are likely to be seen in sputum examination?
Transmission of pulmonary TB to others is by droplet nuclei, which are aerosolized usually by coughing. The tiny droplets dry rapidly; the smallest (<5-10 m in diameter) may remain suspended in the air for several hours and may reach the terminal air passages when inhaled. There may be as many as 3000 infectious nuclei per cough. Reference: Harrisons Principles of Internal Medicine, 18th Edition, Page 1342
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