Tuberculosis (TB) is a bacterial infection that often infects the lungs. Other organs, such as the kidneys, spine, or brain, may also be affected. So can the lymph glands and other parts of the body. TB is mainly spread from person to person through droplets in the air when someone with TB of the lungs coughs. It can also become an active infection after not being active for a long time in someone who had been previously exposed.

There is a difference between being infected with TB bacteria and having active tuberculosis disease.

The stages of TB are:

1. Exposure. This happens when a person has been in contact with, or exposed to, another person who has TB, but did not acquire the infection. The exposed person will have a negative skin test, a normal chest X-ray, and no signs or symptoms of the disease.
2. Latent TB infection. This happens when a person has a little bit of TB bacteria in their body without symptoms of the disease. The infected person's immune system walls off the TB organisms, usually in the upper part of one or both lungs. The TB stays inactive throughout life in most people who are infected. This person would have a positive skin or blood test for TB but a normal chest X-ray or one that only shows scarring from the disease. They would have no signs of active infection like cough, fever or chills, night sweats, or weight loss, which are the common symptoms of active TB.
3. TB disease or Active TB. This person has signs and symptoms of an active TB infection. The person could have a positive or negative skin or blood test for TB and a positive chest X-ray, sputum culture, lung biopsy, or other finding showing an active infection.

The main TB bacterium is Mycobacterium tuberculosis (M. tuberculosis). Many people infected with this bacterium never have active TB. They remain in the inactive (latent) TB stage. But some will develop active TB anytime from months to years, or even decades, after being exposed. The highest risk of active TB is in the first two years after infection. The chance of developing active TB is highest in babies and children and in older adults. It also is more likely in people with a weak immune system. This includes people with HIV, an organ or stem cell transplant, or who are taking immune suppressing medicines.

The TB bacterium is spread through the air most often when a person with an active lung infection coughs, sneezes, speaks, sings, or laughs. It's very unlikely to be spread from personal items that a person with TB has touched. Good ventilation can limit the spread of TB to other people. But early diagnosis and treatment of the person with active TB is most important. It's also important to limit other people's exposure. This means using masks and respiratory isolation.

TB affects all ages, races, income levels, and genders. Those at higher risk include:

• People who live or work with others who have TB.
• Those who can't access healthcare.
• Homeless people.
• People from countries where TB is more common.
• People in group settings, such as nursing homes or prisons.
• People who abuse alcohol.
• People who use injection drugs.
• People with a weak immune system, including those who have HIV, cancer, a transplant, or are taking medicines that suppress the immune system.
• Healthcare workers who come in contact with high-risk populations.
• People living with someone or in close contact with someone who has active TB.

Symptoms may vary but the most common symptoms of active TB include:

• Prolonged cough lasting weeks.
• Chest pain.
• Feeling tired and weak (fatigue).
• Loss of appetite.
• Unintended weight loss.
• Poor growth in children.
• Fever.
• Coughing blood or sputum.
• Night sweats.
• Shortness of breath.
• Back pain.

The symptoms of TB may look like other lung conditions or health problems. Talk with a doctor for a diagnosis.

The first test usually done if TB is suspected is either a skin test called a PPD or, more recently, a blood test called a Quantiferon TB Gold test. These tests can't distinguish between latent and active TB infections. If either is positive, you may have a active TB, but you usually don't. In the skin test (called a PPD), a small amount of testing material is injected into the top layer of the skin making a little bubble. If the bump expands to a pre-determined size in the next 48 hours when you have to return to have it read by a professional, the test indicates a TB infection. A blood test called QuantiFERON-TB or T-SPOT may also be used. For positive tests additional testing will be ordered to determine if there is an active infection present. This requires sputum tests (if in the lungs) or possibly biopsies because you need to confirm an active infection by visualizing bacteria under a microscope or in a culture. . Other tests that may be key for diagnosing TB include X-rays and sputum tests.

TB skin or blood tests are suggested for people:

• Who are at high-risk for active TB.
• Who live or work in areas where TB is common or are in close contact with someone with active TB.
• People who are recommended treatment if latent TB is diagnosed.

In children, the American Academy of Pediatrics recommends testing:

• If the child may have been exposed in the last 5 years.
• If the child has an X-ray that looks like TB.
• If the child has any TB symptoms.
• If the child comes from a country where TB is common.
• For children living with HIV.
• For children receiving medicines that suppress the immune system.
• For children who are in detention facilities.
• For children who are exposed to high-risk people.
• If the child's parent has come from a high-risk country.
• If the child has traveled to high-risk areas.
• If the child lives in a densely populated area.

Treatment varies depending on if you have latent or active TB. Treatment may include:

• Short-term hospital stay. This can be for both types.
• For latent TB: Often a 3- to 9-month course of one or two antibiotics will be given to kill off the TB organisms in the body. The most common antibiotics prescribed are rifampin, isoniazid, and rifapentine. Your doctor can review the treatment choices. They may recommend one as the best choice for you, taking into account many factors.
• For active TB: Your doctor may prescribe 2 to 4 or more antibiotics in combination for 6 to 9 months or longer. Examples include isoniazid, rifampin, pyrazinamide, and ethambutol. People often begin to improve within a few weeks of starting treatment. After several weeks of treatment with the correct medicines, the person is often no longer contagious. But medicine must be finished for the greatest chance of cure, and to reduce the chances of developing TB that is drug resistant.

If TB of the lung is not treated early or if treatment isn't followed, long-lasting (permanent) lung damage can result. TB can also cause infection of the bones, spine, brain and spinal cord, lymph glands, and other parts of the body. It can damage those areas and cause short-term (temporary) or permanent symptoms from the damage. Uncontrolled TB can lead to death and remains a leading infectious cause of death worldwide.

It can also spread to other vulnerable people in the community. TB is among the top 10 causes of death worldwide.

If you will be spending time with anyone with active TB, wear a strongly filtering face mask. And try not to stay in a small, enclosed space with poor ventilation. People who work in situations where there is a high risk for contact with people infected with TB should be tested for TB on a routine basis. This includes healthcare and shelter workers. In countries outside the U.S. where TB is more common, a childhood vaccine called BCG is often given to babies and small children. But it does not always protect people from getting TB.

Let your doctor know if your symptoms get worse or you get new symptoms.

• Tuberculosis is a bacterial infection that often infects the lungs.
• It may also affect the bones, spine, brain, lymph glands, and other parts of the body.
• Being infected with the TB bacteria is not the same as having active tuberculosis disease.
• There are 3 stages of TB: exposure, latent, and active disease.
• A TB skin test or a TB blood test can often diagnose the infection. But other testing is also often needed.
• Treatment exactly as recommended is needed to cure the disease and prevent its spread to other people.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions.