Tuberculosis and HIV disease

November 2004     View PDF     En español

Tuberculosis (TB) is caused by a bacterium called Mycobacterium tuberculosis. It usually infects the lungs, but it can also enter the blood and infect almost any part of the body. This includes the liver, kidneys, stomach and gut, bones, skin, breasts, brain and spinal cord. TB in these places is more common in children and people with weak immune systems, including people living with HIV.

TB is spread when a person with active TB disease coughs, sneezes or spits. Tiny droplets of fluid from the lungs are carried in the air and if other people breathe in these droplets they can get infected. TB can also pass from a mother to her unborn child before and after birth. However, it’s more common for a baby to catch it after birth, due to close contact with its mother. If you or someone you live with has TB, you are all at risk for TB infection and TB screening is recommended for the whole family. Depending on your health and the health of people you live with, TB preventive therapy might be recommended for others in your household.

You are not likely to catch TB from a stranger coughing on a bus. Even if a healthy person spends 24 hours a day for two months with someone with active disease, there’s still only a 50% chance that he or she will catch TB, though certainly people with weakened immune systems are more at risk.