Tuberculosis (TB) is moderately contagious and spreads primarily through the air when a person with active lung TB coughs, sneezes, talks, or sings, releasing infectious droplets. A person with active TB can infect about 10–15 people through close contact over the course of a year. TB is only contagious in its active form; people with latent TB infection are not contagious. Transmission usually requires close and prolonged contact, especially in indoor or poorly ventilated spaces. TB germs can remain airborne and infective for several hours under the right conditions. Proper treatment generally reduces contagiousness significantly within the first two weeks of therapy.
Key points:
- Active TB (usually lung TB) is contagious, latent TB is not.
- Spread occurs through airborne droplets released by coughing, sneezing, talking, or singing.
- Close, prolonged indoor contact poses a higher risk.
- Without treatment, a person with active TB can infect 10–15 others per year.
- Contagiousness drops after a few weeks of appropriate treatment.
This makes TB contagious enough to be a major public health concern, but it is preventable and curable with proper care and precautions.
