50 year old, Rishi has a diagnosis of pulmonary tuberculosis. How many infectious nuclei per cough are likely to be seen in sputum examination?: (A) 1000, (B) 2000, (C) 3000, (D) 4000
Answer is C. 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