Hesperian Health Guides
How TB Spreads
For every 1,000 people in the world, around 250 of them are infected with the TB germ, but only 1 of them is actually sick with active TB disease.
TB spreads from one person to another when someone sick with TB in their lungs coughs germs into the air. TB germs can live in the air for hours.
People who are infected with TB but not sick with signs of TB, and those who are sick with TB in other parts of the body, are not contagious. A person is probably no longer contagious after taking medicines for about a month.
Because women care for many people, if they are sick with TB, they may spread it to others in the household. TB can spread from a pregnant person to their child during pregnancy, birth, and breastfeeding. (See “TB treatment during pregnancy”.)
If TB is not treated, a person sick with TB in their lungs will infect about 10 more people with TB every year
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| This year, about 10 people will be infected by each person who is sick with TB today. |