What is tuberculosis?
Tuberculosis (TB) is an infectious disease that mostly affects the lungs, but can also affect body parts like the spine, brain or kidneys. Everyone who is infected does not get sick. If you do get sick, you need treatment.
How common is tuberculosis?
About 33 percent of the world's population, nearly 2.5 billion people, is infected with TB. Although TB was once the leading cause of death in the United States, the number of cases fell rapidly in the 1940s and 1950s after treatments were found.
According to statistics from the Centers for Disease Control (CDC), there were 9,272 tuberculosis cases reported in the United States in 2016. For TB, there is a national incidence rate of 2.9 cases per 100,000 people.
Symptoms and Causes
What causes tuberculosis?
TB is caused by the bacterium Mycobacterium tuberculosis. The germs are spread through the air and usually infect the lungs, but can also infect other parts of the body. Although TB is infectious, it does not spread easily. You usually have to spend a lot of time in contact with someone who is contagious in order to catch it.
How is tuberculosis spread?
TB can be spread when a person with active TB disease releases germs into the air through coughing, sneezing, talking, singing, or even laughing. Only people with an active pulmonary infection are contagious. Most people who breathe in TB bacteria are able to fight the bacteria and stop it from growing. The bacterium becomes inactive in these individuals, and is referred to as a latent TB infection. Approximately 10 percent of the US population has latent infection.
Although the bacteria are inactive, they still remain alive in the body, and can become active later. Some people can have a latent TB infection for a lifetime, without it ever becoming active and developing into TB disease. However, TB can become active if the immune system becomes weakened and cannot stop the bacteria from growing. This is when the latent TB infection becomes TB disease.
What are the symptoms of tuberculosis?
People with inactive TB do not exhibit symptoms. However, they may have a positive skin reaction test.
Those with TB disease can show any of the following symptoms:
- Bad cough (lasting longer than 2 weeks)
- Pain in the chest
- Coughing up blood or sputum (mucus)
- Fatigue or weakness
- Loss of appetite
- Weight loss
- Night sweats
Diagnosis and Tests
What kinds of tests are used to diagnose tuberculosis?
There are two kinds of screening tests for TB: the Mantoux tuberculin skin test (TST) and the blood test, called the interferon gamma release assay (IGRA).
For the TST, a healthcare provider will inject a small amount of a substance called purified protein derivative (PPD) under the skin of the forearm. After 2-3 days, the person must go back to the healthcare provider, who will look at the injection site. If the person has a TB infection, there will be a reddish lump.
For the IGRA, a healthcare provider will draw blood and send the sample to the lab.
Further tests to determine if an infection is active or if lungs are infected include:
How do I know if I should get tested for tuberculosis?
You should consider a TB screening test if:
- You are a resident or employee in group settings where the risk is high (i.e., jails, hospices, skilled nursing facilities, shelters and other healthcare facilities).
- You work in a mycobacteriology laboratory.
- You have been in contact with a person who is known or suspected to have TB disease.
- Your body's resistance to illness is low because of a weak immune system.
- You think you might already have TB disease and are having symptoms.
- You are from a country or lived in a country where TB disease is prevalent.
- You have injected illicit drugs.
Others who are at risk for TB include:
- People with immature or impaired immune systems, such as babies and children
- People with kidney disease, diabetes, or other chronic (long-term) illness
- People who have received organ transplants
- People who are being treated with chemotherapy for cancer or other types of treatments for immune system disorders
The incidence rates for minority groups in the United States are higher than the incidence rates for whites.
Management and Treatment
Can tuberculosis be cured?
Yes, TB can be cured, even in people with HIV infection. Drugs used to treat TB infection and disease include isoniazid (Hyzyd®), rifampin (Rifadin®), ethambutol (Myambutol®), pyrazinamide (Zinamide®), and a combination of isoniazid and rifapentine.
You must take all of the medication your doctor tells you to, or else not all of the bacteria will be killed. You will have to take these medications for as long as you are told—sometimes up to 9 months.
Can tuberculosis be prevented?
Yes. You usually have to be in contact with someone with active TB for a long time before becoming infected. The most important measure to prevent the transmission of TB in the hospital is to have proper ventilation and/or proper personal protective equipment (respirator).
Some countries (but not the United States) use a TB vaccine called bacillus Calmette-Guerin (BCG). The vaccine has been shown to work better in children than in adults. It may also make skin tests for TB less accurate.
Where can I learn more about tuberculosis?
CDC Hotline: 1.800-CDC-INFO (1.800.232.4636)