Tuberculosis (TB) is a common, serious infection caused by bacteria called Mycobacterium tuberculosis.
TB affects millions of people worldwide, particularly in developing countries
TB is spread by the coughs and sneezes of untreated infected people
You get TB by breathing in tuberculosis bacteria
TB usually affects your lungs but can affect almost any organ
Most infected people don't get sick, but the bacteria stay in the body
If TB becomes active, you typically get cough, fever, and night sweats, and lose weight
People with HIV are more likely to get active TB and more likely to die from it
You need to take several different antibiotics for at least 6 months
Tuberculosis has 3 stages:
In primary infection, the TB bacteria enter your lungs and sometimes spread to other parts of your body. Only a few people with primary infection get sick.
In latent ("latent" means hidden) infection, the body's defenses (immune system) attack the TB bacteria and seal them off inside small clumps of scar tissue. Your body may eventually kill the bacteria, but the bacteria often stay alive and inactive for many years. About 5 to 10% of people with latent infection get active disease.
In active disease, bacteria that were sealed off inside clumps of scar tissue become active and break free. Active disease makes you sick and able to spread the infection to others.
TB is caused by breathing in the tuberculosis bacteria, Mycobacterium tuberculosis.
The bacteria gets into the air when a person with active disease coughs, sneezes, or even just talks.
Diseases and drugs that weaken your immune system make TB more likely to become active.
The most common risk factor is:
Other risk factors include:
Sometimes TB becomes active even if you don't have risk factors.
TB usually doesn't cause symptoms right away. In fact, most people who are infected will never have symptoms.
If you have symptoms, they usually involve your lungs and start within 2 years of primary infection. You may have:
Less often, you'll have symptoms of other organs that are infected with the TB bacteria. For example, kidney infection causes back pain and blood in your urine. Brain infection causes headache, confusion, and drowsiness. Spine infection causes back pain.
If you have symptoms that might be TB, doctors look for active disease using:
If the results of these tests aren't clear, doctors may do a TB skin test or a blood test.
The TB skin test is called a PPD. A health care worker injects a little bit of protein from TB bacteria just under the skin of your arm. If you've been exposed to TB, in about 2 days you get a hard bump in the area.
Screening tests look for disease in people who don't have any symptoms. Because TB often doesn't cause any symptoms, you need regular screening tests if you're at risk for TB.
You might need a screening test if you:
Screening tests include:
If your skin or blood test is positive, doctors examine you and do a chest x-ray to see if you have active disease. If you don't have active disease, the positive screening test means you have a latent infection.
There are many different ways doctors treat active TB depending on your disease, test results, and other circumstances. But in general you'll:
You may need to be in the hospital if you're very sick, have no place to live, or live someplace where it's hard to limit who you're in contact with. For example, if you live in a nursing home, dormitory, or shelter.
Unless your TB infection is extremely resistant to drugs, you won't spread it to healthy people after you've been taking antibiotics for a week or two. Until then, you need to take some precautions.
If you're treated at home:
If you live with people at high risk, such as young children or people with HIV, you may need to take precautions until tests show the TB is under control.
If you're being treated in the hospital, you may also have to:
There is a vaccine for TB. It's called BCG. However, it makes your PPD skin test turn positive. So if you've had the vaccine, doctors can't use the skin test to screen you for TB. Because of this, the vaccine is used mainly for children in countries where TB is common.