What is tuberculosis?
The Tuberculosis and Chest Service puts it this way: tuberculosis, commonly called 肺癆, is a disease in which the tubercle bacillus attacks the lung. It can also attack other organs — the lymph nodes, bones, joints, spine, brain and kidneys.
The colloquial name and the medical name refer to the same disease. Both are used on this page, because a doctor will generally say 結核病 while everyday conversation says 肺癆.
That tuberculosis is not confined to the lung matters in practice: persistent bone pain, joint swelling or enlarged lymph nodes can also be tuberculosis, and need not come with a cough.
How does it spread?
The Tuberculosis and Chest Service states that a person with open tuberculosis spreads droplets carrying the bacillus through the air to others.
“Open” means the sputum contains transmissible bacilli. Not every patient is infectious, and infectiousness falls once effective treatment begins — which is why starting early and completing the course concerns both the patient and those around them.