Tuberculosis (TB) is a disease that comes from a bacteria called Mycobacterium tuberculosis. Typically, the bacteria will get into your lungs and cause an infection there, but it can also attack other areas of your body, including your kidneys, brain, and spine. It’s called extrapulmonary tuberculosis when found in areas of your body outside of your lungs.
Not all people who come into contact with — and harbor — these bacteria will become sick. Most people’s immune systems are able to fight off the bacteria and keep them from multiplying.
If this is the case, you’ll usually have a positive result when taking a skin test for TB, but you won’t be able to spread the disease to others. You also won’t have any symptoms. This is called a latent tuberculosis infection.
People rarely develop the symptomatic version of the infection — tuberculosis disease — if they have a latent tuberculosis infection. This is only likely to happen if another condition weakens your immune system. This will allow the bacteria to start multiplying again.
Some people's immune systems can’t suppress TB infection for any substantial amount of time. Instead, the bacteria never stop multiplying after entering your body. You become both sick and infectious with tuberculosis disease, sometimes just weeks after exposure.
What causes tuberculosis to spread?
Tuberculosis is contagious. The bacteria are spread through the air by people who have active tuberculosis disease in their lungs when they:
You need to actively inhale the bacteria that cause TB to become infected. This tends to require an extended amount of contact with an infected person in a poorly ventilated space.
You’re far less likely to pick up an infection from contact with an infected person’s personal items. Shaking hands or sharing a toilet with an infected person shouldn’t result in an infection. Drinking glasses, clothing, bedding, and similar items are also normally safe to touch.
Who is most at risk for tuberculosis?
People of all ages and races can become infected with tuberculosis, but some people are at higher risk than others of encountering the bacteria. This category includes:
- People who live or commonly interact with someone with TB
- People who don’t have homes
- People with no access to healthcare
- People consistently in group settings — particularly older people in nursing homes
- People with weak immune systems
- People who drink too much alcohol
- People who use intravenous drugs
- People from countries with much higher rates of TB than the U.S.
- Healthcare workers
How is tuberculosis diagnosed?
The most common test for tuberculosis is a skin test.
A medical professional will inject a small amount of testing material into your top layer of skin. After two to three days, they’ll evaluate the spot. If a bump of a particular size has developed at the site of your test, then there’s a chance that you’re positive for some form of tuberculosis infection.
Blood tests and x-rays of your lungs can also help your doctor diagnose your condition.
How can you prevent tuberculosis?
Since tuberculosis is the number-one infectious cause of death worldwide, you should take preventative care to keep yourself and your children from becoming infected.
If you need to spend a lot of time with someone with an active TB infection, be sure to wear a facemask and choose a spot with good ventilation.
If your job commonly brings you into contact with TB, then be sure to get regular testing so you can catch any infections early.
If you already have an active tuberculosis infection, then you want to prevent the infection from spreading to other people. Always cover your mouth and nose when you cough and sneeze. Also be sure to consistently take any needed medications.
There are also childhood vaccinations in countries where tuberculosis is common. The U.S. doesn’t currently recommend this for all children, though, due to low rates of infection in the U.S.
When should you contact your doctor?
Tuberculosis can be deadly if you don’t get proper treatment. Talk to your doctor if you or your child has been exposed to someone with an active tuberculosis infection or if you plan on traveling to a country with a high rate of TB.
You should also contact your doctor as soon as possible if you notice that you or your child has a number of symptoms of tuberculosis. Possible symptoms include:
- A cough that lasts for longer than three weeks
- Coughing up mucus or blood
- Chest pain
- Unintended weight loss
- Loss of appetite
- Weakness and tiredness
- Chills and night sweats
There can be additional symptoms if your infection is in an area of your body that’s outside of the lungs.
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Centers For Disease Control and Prevention: "Tuberculosis (TB): Basic TB Facts," "Tuberculosis (TB): Latent TB Infection and TB Disease."
Johns Hopkins Medicine: "Tuberculosis TB."
National Institute of Allergy and Infectious Diseases: "Tuberculosis."
New York State Department of Health: "Tuberculosis (TB)."
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