What system does tuberculosis affect?


Department of Health

Tuberculosis (TB)

Last Reviewed: August 2018

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What is tuberculosis?

Tuberculosis is a bacterial disease usually affecting the lungs (pulmonary TB). Other parts of the body can also be affected, for example lymph nodes, kidneys, bones, joints, etc. (extrapulmonary TB).

Who gets tuberculosis?

Tuberculosis can affect anyone of any age. Once a person has TB infection but does not appear sick, he or she has a higher chance of developing TB disease if the person has HIV infection, is younger than 5 years old, was infected with TB germs within the last 2 years, has other health problems like diabetes that make it hard for the body to fight germs, abuses alcohol or drugs, or was not treated correctly for TB disease in the past.

How is tuberculosis spread?

Tuberculosis is spread through the air when a person with untreated TB disease of the lungs coughs, sneezes, laughs, or sings. A person must be in close contact with someone with untreated TB disease of the lungs for a long period of time and needs to breathe in TB germs for infection to occur. TB is NOT spread by sharing silverware or cups, or sharing saliva when kissing someone.

What is the difference between latent tuberculosis infection and tuberculosis disease?

Latent tuberculosis infection (LTBI) means the person has the TB germs in the body (usually lungs), but he/she is not sick and has no symptoms because the germs are sleeping in the body. In latent TB, the person has a positive TB skin test or TB blood test, a normal chest x-ray, no symptoms of tuberculosis, and no TB germs found in the sputum (phlegm). Tuberculosis disease is when the person has symptoms, a positive TB skin test or TB blood test, a chest x-ray showing TB disease (if disease is in the lungs), and have TB germs in the sputum (phlegm). In order to spread the TB germs, a person must have TB disease of the lungs or throat. Having latent TB infection is not enough to spread the germ. However, people with latent TB infection may develop TB disease in the future. To prevent developing TB disease, people with latent TB infection should take medicine.

What are the symptoms of tuberculosis?

The symptoms of TB include a low-grade fever, night sweats, weakness or tiredness, and weight loss. If TB is in the lungs, the person may also cough, have chest pain, shortness of breath or might be coughing up blood. Other symptoms depend on the part of the body affected by the TB germs.

How soon do symptoms appear?

Most people infected with the germ that causes TB never develop TB disease. If TB disease does develop, it can occur two to three months after infection or years later. The risk of TB disease lessens as time passes. Treatment can prevent the development of disease.

When and for how long is a person able to spread tuberculosis?

A person with TB disease may be able to spread the TB germs until he/she has been on medicine for several weeks. However, a person with latent TB infection, but not disease, cannot spread the infection to others, since there are no TB germs in the sputum (phlegm).

What is the treatment for tuberculosis?

People with latent TB infection should be seen by a health care provider for treatment, which usually includes taking medication for three to nine months. People with TB disease must take several medications for six months or more. Initial medications include at least four anti-TB drugs, and medications may be altered based on laboratory test results. The exact medication plan must be determined by a health care provider. Directly observed therapy (DOT) programs are recommended for all persons with TB disease to help them complete their treatment.

What is Directly Observed Therapy (DOT)?

DOT is when a person with TB disease meets with a health care worker every day or several times per week. The person with TB disease and the health care worker meet at a place that both agree on. Medicines are taken at this place while the health care worker watches the person with TB disease. DOT helps in several ways. The health care worker can help the person with TB disease remember to take all his/her medicines and complete treatment. This means the person with TB disease will get well as soon as possible. The health care worker will make sure that the medicines are working as they should. This health care worker will also watch for side effects and answer questions that the person with disease may have about TB.

What can be the effect of not being treated for tuberculosis?

In addition to spreading the disease to others, an untreated person may become severely ill or die.

What can be done to prevent the spread of tuberculosis?

The most important way to stop the spread of tuberculosis is for people with TB disease to cover the mouth and nose when coughing, and to take all the TB medicine exactly as instructed by the health care provider. It is also important that people with latent TB infection be treated so they do not get TB disease later and spread it to others.

What is multidrug-resistant tuberculosis (MDR-TB)?

This refers to the ability of some strains of TB to grow and multiply even in the presence of certain drugs which would normally kill them.

What is extensively drug-resistant tuberculosis (XDR-TB)?

Extensively drug-resistant TB (XDR-TB) is a subset of MDR-TB in which the strains of TB bacteria are resistant to nearly all medicines used to treat TB disease. These strains are very difficult to treat.

Who gets MDR-TB?

People with drug sensitive TB disease may develop drug resistant tuberculosis if they fail to take their TB medications as instructed, as well as people with TB disease who have not been given a treatment plan that works against the TB germs. People with MDR-TB can transmit the drug resistant germs to other people.

What is the treatment for multidrug-resistant tuberculosis?

People with disease due to drug resistant germs, should have a health care provider who is an expert in treating drug resistant TB. People with drug resistant disease must be treated with special medications which are not as good as the usual medications for TB. Treatment takes much longer than regular TB and drugs have more side effects.

What can be done to prevent the spread of MDR-TB?

Ensuring people with MDR-TB take all their medication and teaching patients to cover their mouth and nose when coughing and sneezing can reduce the risk of spread of MDR-TB. In addition, directly observed therapy should be used to ensure people with drug resistant TB complete their treatment.

What is TB?

Tuberculosis, or TB, is a bacterial infection that usually infects the lungs. Other organs, such as the kidneys, spine, or brain may also be involved. TB is primarily spread from person to person in an airborne manner, such as when an infected person coughs or sneezes. It can also cause an active infection after a period of not being active in someone who was exposed at an earlier time.

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

The following are the stages of TB:

  1. Exposure. This happens when a person has been in contact with, or exposed to, another person who has TB. 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 TB bacteria in his or her body, but does not have symptoms of the disease. The infected person’s immune system walls off the TB organisms, and the TB remains inactive throughout life in most people who are infected. This person would have a positive skin test, but a normal chest X-ray.
  3. TB disease. This describes the person who has signs and symptoms of an active infection. The person would have a positive skin test and a positive chest X-ray.

What causes TB?

The main TB bacterium is Mycobacterium tuberculosis (M. tuberculosis). Many people infected with this bacterium never develop active TB. They remain in the latent (inactive) TB stage. However, in people with weak immune systems, especially those with HIV (human immunodeficiency virus), or those receiving medicines that suppress the immune system, TB organisms can overcome the body’s defenses, multiply, and cause an active disease.

The TB bacterium is spread through the air when an infected person coughs, sneezes, speaks, sings, or laughs. It’s not likely to be spread through personal items, such as clothing, bedding, a drinking glass, eating utensils, a handshake, a toilet, or other items that a person with TB has touched. Good ventilation is the most important measure to prevent the transmission of TB.

Who is at risk for TB?

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

  • People who live or work with others who have TB
  • Those who can’t access health care
  • Homeless people
  • People from other countries where TB is prevalent
  • People in group settings, such as nursing homes
  • People who abuse alcohol
  • People who use intravenous drugs
  • People with weak immune systems
  • The elderly
  • Healthcare workers who come in contact with high-risk populations

What are the symptoms of TB?

The following are the most common symptoms of active TB. However, each person may experience symptoms differently:

  • Cough that lasts 3 weeks or longer
  • Chest pain
  • Fatigue
  • Loss of appetite
  • Unintended weight loss
  • Poor growth in children
  • Fever
  • Coughing blood or sputum
  • Chills or night sweats

The symptoms of TB may look like other lung conditions or medical problems. Talk with a healthcare provider for a diagnosis.

How is TB diagnosed?

TB is often diagnosed with a skin test. In this test, a small amount of testing material is injected into the top layer of the skin. If a certain size bump develops within 2 or 3 days, the test may be positive for tuberculosis infection. Other tests include X-rays and sputum tests. A blood test can be done in place of the TB skin test.

TB skin tests are suggested for those:

  • In high-risk categories
  • Who live or work in close contact with people who are at high risk
  • Who have never had a TB skin test

For skin testing in children, the American Academy of Pediatrics recommends testing:

  • If the child is thought to have been exposed in the last 5 years
  • If the child has an X-ray that looks like TB
  • If the child has any symptoms of TB
  • If the child comes from a country where TB is prevalent
  • For children 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

How is TB treated?

Your healthcare provider will figure out the best treatment for you based on:

  • How old you are
  • Your overall health and past health
  • How sick you are
  • How well you can handle specific medicines, procedures, or therapies
  • How long the condition is expected to last
  • Your opinion or preference

Treatment may include:

  • Short-term hospitalization
  • For latent TB which is newly diagnosed: Usually a 6 to 12 month course of antibiotic called isoniazid will be given to kill off the TB organisms in the body. Some people with latent TB may be treated with a shorter course of 2 antibiotics for only 3 months.
  • For active TB: Your healthcare provider may prescribe 3 or more antibiotics in combination for 6 to 9 months or longer. Examples include: isoniazid, rifampin, pyrazinamide, and ethambutol. People usually begin to improve within a few weeks of the start of treatment. After several weeks of treatment with the correct medicines, the person is usually no longer contagious, if treatment is carried through to the end, as prescribed by a healthcare provider.

What are the complications of TB?

If TB is not treated early or if treatment isn’t followed, permanent lung damage can result.

Can TB be prevented?

If you will be spending time with a person or people with active TB, wear a 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 encountering people infected with TB, such as healthcare workers, should be tested for TB on a routine basis. In countries outside the U.S. where TB is more common, a childhood vaccine is often given.

When should I call my healthcare provider?

If your symptoms get worse or you get new symptoms, let your healthcare provider know.

Key points about TB

  • Tuberculosis is a bacterial infection that usually infects the lungs.
  • It may also affect the kidneys, spine, and brain.
  • Being infected with the TB bacterium 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 diagnose the disease.
  • Treatment exactly as recommended is necessary to cure the disease and prevent its spread to other people.

Next steps

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

  • 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 provider 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 provider 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 provider if you have questions.

Fact Sheets

Tuberculosis: General Information

Tuberculosis (TB) is a disease caused by germs that are spread from person to person through the air. TB usually affects the lungs, but it can also affect other parts of the body, such as the brain, the kidneys, or the spine. A person with TB can die if they do not get treatment.

What Are the Symptoms of TB?

The general symptoms of TB disease include feelings of sickness or weakness, weight loss, fever, and night sweats. The symptoms of TB disease of the lungs also include coughing, chest pain, and the coughing up of blood. Symptoms of TB disease in other parts of the body depend on the area affected.

How is TB Spread?

TB germs are put into the air when a person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings. These germs can stay in the air for several hours, depending on the environment. Persons who breathe in the air containing these TB germs can become infected; this is called latent TB infection.

What is the Difference Between Latent TB Infection and TB Disease?

People with latent TB infection have TB germs in their bodies, but they are not sick because the germs are not active. These people do not have symptoms of TB disease, and they cannot spread the germs to others. However, they may develop TB disease in the future. They are often prescribed treatment to prevent them from developing TB disease.

People with TB disease are sick from TB germs that are active, meaning that they are multiplying and destroying tissue in their body. They usually have symptoms of TB disease. People with TB disease of the lungs or throat are capable of spreading germs to others. They are prescribed drugs that can treat TB disease.

What Should I Do If I Have Spent Time with Someone with Latent TB Infection?

A person with latent TB infection cannot spread germs to other people. You do not need to be tested if you have spent time with someone with latent TB infection. However, if you have spent time with someone with TB disease or someone with symptoms of TB, you should be tested.

What Should I Do if I Have Been Exposed to Someone with TB Disease?

People with TB disease are most likely to spread the germs to people they spend time with every day, such as family members or coworkers. If you have been around someone who has TB disease, you should go to your doctor or your local health department for tests.

How Do You Get Tested for TB?

There are two tests that can be used to help detect TB infection: a skin test or TB blood test. The Mantoux tuberculin skin test is performed by injecting a small amount of fluid (called tuberculin) into the skin in the lower part of the arm. A person given the tuberculin skin test must return within 48 to 72 hours to have a trained health care worker look for a reaction on the arm. The TB blood tests measure how the patient’s immune system reacts to the germs that cause TB.

What Does a Positive Test for TB Infection Mean?

A positive test for TB infection only tells that a person has been infected with TB germs. It does not tell whether or not the person has progressed to TB disease. Other tests, such as a chest x-ray and a sample of sputum, are needed to see whether the person has TB disease.

What is Bacille Calmette–Guèrin (BCG)?

BCG is a vaccine for TB disease. BCG is used in many countries, but it is not generally recommended in the United States. BCG vaccination does not completely prevent people from getting TB. It may also cause a false positive tuberculin skin test. However, persons who have been vaccinated with BCG can be given a tuberculin skin test or TB blood test.

Why is Latent TB Infection Treated?

If you have latent TB infection but not TB disease, your doctor may want you to take a drug to kill the TB germs and prevent you from developing TB disease. The decision about taking treatment for latent infection will be based on your chances of developing TB disease. Some people are more likely than others to develop TB disease once they have TB infection. This includes people with HIV infection, people who were recently exposed to someone with TB disease, and people with certain medical conditions.

How is TB Disease Treated?

TB disease can be treated by taking several drugs for 6 to 12 months. It is very important that people who have TB disease finish the medicine, and take the drugs exactly as prescribed. If they stop taking the drugs too soon, they can become sick again; if they do not take the drugs correctly, the germs that are still alive may become resistant to those drugs. TB that is resistant to drugs is harder and more expensive to treat. In some situations, staff of the local health department meet regularly with patients who have TB to watch them take their medications. This is called directly observed therapy (DOT). DOT helps the patient complete treatment in the least amount of time.

Additional Information

CDC. Questions and Answers About TB.

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