What causes TB?

  • TB is caused by the bacterium Mycobacterium tuberculosis.
  • TB in the lungs or throat can be infectious i.e. the bacteria can be spread to other people. TB in other parts of the body is usually not infectious.
  • TB is spread mainly through the air. When infectious people cough, sneeze, talk, laugh or spit, droplets containing bacteria are sprayed into the air. People nearby may inhale these bacteria and become infected. Bacteria can stay air-borne for a long time, and can remain active in house dust for weeks.
  • However, transmission usually occurs only after substantial exposure to someone with active TB. People with TB disease are most likely to spread it to those they spend time with daily, such as family members and co-workers. You are unlikely to get TB from someone coughing in a public place. You cannot get TB from handshakes, toilet seats, or sharing eating utensils, bedclothes or clothing with people who have TB.
  • Infection can also be acquired from contact with an infected cow or through drinking contaminated milk. However, this is an extremely rare way of getting TB. Most milk is pasteurized, and dairy herds are usually kept under veterinary control.

- Reviewed by Joanna Evans, PhD, Molecular Mycobacteriology Research Unit, Division of Medical Microbiology
Institute of Infectious Diseases and Molecular Medicine, University of Cape Town, February 2011

We live in a world where facts and fiction get blurred
In times of uncertainty you need journalism you can trust. For 14 free days, you can have access to a world of in-depth analyses, investigative journalism, top opinions and a range of features. Journalism strengthens democracy. Invest in the future today. Thereafter you will be billed R75 per month. You can cancel anytime and if you cancel within 14 days you won't be billed. 
Subscribe to News24
Voting Booth
Have you entered our Health of the Nation survey?
Please select an option Oops! Something went wrong, please try again later.
27% - 9952 votes
73% - 26301 votes