Tuberculosis (TB) is a disease caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain. If not treated properly, TB disease can be fatal. TB disease was once the leading cause of death in the United States
BASIC TB FACTS
TB” is short for tuberculosis. TB disease is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain. If not treated properly, TB disease can be fatal.
How TB Spreads
TB is spread through the air from one person to another. The TB bacteria are put into the air when a person with active TB disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected.
TB is NOT spread by
- shaking someone’s hand
- sharing food or drink
- touching bed linens or toilet seats
- sharing toothbrushes
Latent TB Infection and TB Disease
Not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist: latent TB infection and active TB disease.
- Latent TB Infection
TB bacteria can live in your body without making you sick. This is called latent TB infection (LTBI). In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria to stop them from growing. People with latent TB infection do not feel sick and do not have any symptoms. The only sign of TB infection is a positive reaction to the tuberculin skin test or special TB blood test. People with latent TB infection are not infectious and cannot spread TB bacteria to others. However, if TB bacteria become active in the body and multiply, the person will get sick with TB disease.
- TB Disease
TB bacteria become active if the immune system can’t stop them from growing. When TB bacteria are active (multiplying in your body), this is called TB disease. TB disease will make you sick. People with TB disease may spread the bacteria to people they spend time with every day. Many people who have latent TB infection never develop TB disease. Some people develop TB disease soon after becoming infected (within weeks) before their immune system can fight the TB bacteria. Other people may get sick years later, when their immune system becomes weak for another reason.
For persons whose immune systems are weak, especially those with HIV infection, the risk of developing TB disease is much higher than for persons with normal immune systems.
The Difference between Latent TB Infection and TB Disease
A Person with Latent TB Infection
A Person with TB Disease
|• Has no symptoms||• Has symptoms that may include:
– a bad cough that lasts 3 weeks or longer
– pain in the chest
– coughing up blood or sputum
– weakness or fatigue
– weight loss
– no appetite
– sweating at night
|• Does not feel sick||• Usually feels sick|
|• Cannot spread TB bacteria to others||• May spread TB bacteria to others|
|• Usually has a skin test or blood test result indicating TB infection||• Usually has a skin test or blood test result indicating TB infection|
|• Has a normal chest x-ray and a negative sputum smear||• May have an abnormal chest x-ray, or positive sputum smear or culture|
|• Needs treatment for latent TB infection to prevent active TB disease||• Needs treatment to treat active TB disease|
Testing for TB Infection
There are two kinds of tests that can be used to help detect TB infection – the TB skin test (TST) and TB blood tests. A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection (LTBI) or 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.
- Mantoux tuberculin skin test
The TB skin test (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.
- TB blood tests
TB blood tests (also called interferon-gamma release assays or IGRAs) measure how the immune system reacts to the bacteria that cause TB. If your health care provider or local health department offers TB blood tests, only one visit is required to draw blood for the test. The QuantiFERON®-TB Gold In-Tube test (GFT-GIT) and T-SPOT®.TB test are two Food and Drug Administration approved TB blood tests. Test results are generally available in 24-48 hours.
Who Should Get Tested for TB
Persons should get tested for TB by their doctor or local health department if they
- have spent time with a person known or suspected to have active TB disease; or
- have HIV infection or another condition that weakens the immune system and puts them at high risk for active TB disease; or
- have symptoms of active TB disease; or
- are from a country where active TB disease is very common (most countries in Latin America and the Caribbean, Africa, Asia, Eastern Europe, and Russia); or
- live somewhere in the United States where active TB disease is more common such as a homeless shelter, migrant farm camp, prison or jail, or some nursing homes); or
- inject illegal drugs.
Testing for TB in BCG-Vaccinated Persons
BCG, or bacille Calmette-Guérin, is a vaccine for TB disease. Many persons born outside of the United States have been BCG-vaccinated. BCG vaccination may cause a positive reaction to the TB skin test, which may complicate decisions about prescribing treatment. Despite this potential for BCG to interfere with test results, the TB skin test is not contraindicated for persons who have been vaccinated with BCG. The presence or size of a TB skin test reaction in these persons does not predict whether BCG will provide any protection against TB disease. Furthermore, the size of a TB skin test reaction in a BCG-vaccinated person is not a factor in determining whether the reaction is caused by latent TB infection (LTBI) or the prior BCG vaccination.
TB blood tests (interferon-gamma release assays or IGRAs), unlike the TB skin tests, are not affected by prior BCG vaccination and are not expected to give a false-positive result in persons who have received prior BCG vaccination.
Diagnosis of TB Disease
Persons suspected of having TB disease should be referred for a medical evaluation, which should include
– Medical history,
– Physical examination,
– Test for TB infection (TB skin test or special blood test),
– Chest radiograph (X-ray), and
– Appropriate laboratory tests
Infection Control and Prevention
New, Simpler Way to Treat Latent TB Infection
Treating latent tuberculosis (TB) infection to prevent progression to TB disease is a cornerstone of the U.S. strategy for TB elimination.
People with latent tuberculosis (TB) infection now have another option when it comes to treatment. A new regimen for the treatment of latent TB infection, called the 12-dose regimen, reduces the number of doses and shortens the duration of treatment
Infection Control in Health Care Settings
All health care settings need an infection-control program designed to ensure prompt detection, airborne precautions, and treatment of persons who have suspected or confirmed TB disease. In order to be effective, the primary emphasis of the TB infection-control program should be on achieving these three goals.
In all health-care settings, particularly those in which persons are at high risk for exposure, policies and procedures for TB control should be developed, reviewed periodically, and evaluated for effectiveness to determine the actions necessary to minimize the risk for transmission of TB.
- Infection Control in Health-Care Settings (Fact sheet)
- Respiratory Protection in Health-Care Settings (Fact sheet)
What to Do If You Have Been Exposed to TB
If you think you have been exposed to someone with TB disease, you should contact your doctor or local health department about getting a TB skin test or a special TB blood test. Be sure to tell the doctor or nurse when you spent time with the person who has TB.
Preventing Latent TB Infection from Progressing to TB Disease
Many people who have latent TB infection never develop active TB disease. But some people who have latent TB infection are more likely to develop active TB disease than others. Those at high risk for developing active TB disease include
- People with HIV infection
- People who became infected with TB bacteria in the last 2 years
- Babies and young children
- People who inject illegal drugs
- People who are sick with other diseases that weaken the immune system
- Elderly people
- People who were not treated correctly for TB in the past
If you have latent TB infection and you are in one of these high-risk groups, you need to take medicine to keep from developing active TB disease. This is called treatment for latent TB infection. There are several treatment options. You and your health care provider must decide which treatment is best for you. If you take your medicine as instructed by your doctor or nurse, it can keep you from developing active TB disease. Because there are less bacteria, treatment for latent TB infection is much easier than treatment for TB disease. A person with active TB disease has a large amount of TB bacteria in the body. Several drugs are needed to treat active TB disease.
Preventing Exposure to TB Disease While Traveling Abroad
Travelers should avoid close contact or prolonged time with known TB patients in crowded, enclosed environments (for example, clinics, hospitals, prisons, or homeless shelters).
Travelers who will be working in clinics, hospitals, or other health care settings where TB patients are likely to be encountered should consult infection control or occupational health experts. They should ask about administrative and environmental procedures for preventing exposure to TB. Once those procedures are implemented, additional measures could include using personal respiratory protective devices.
- Tuberculosis Information for International Travelers (Fact sheet)
While TB cases in the United States have been declining since 1993, TB remains one the world’s deadliest diseases. One-third of the world’s population is infected with the bacteria that cause TB, and each year, nearly 9 million people around the world become sick with TB disease.
In the United States a total of 11,182 TB cases were reported in 2010. Achieving the goal of TB elimination in the United States means not only treating those people who already have TB disease, but also successfully treating those with latent TB infection.
Safety First, Safety Always!
Information from CDC and WebMD
Our post today comes to us courtesy of Ken Oswald
Safety and Security Manager for Plateau