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Screening for TB.

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Presentation on theme: "Screening for TB."— Presentation transcript:

1 Screening for TB

2 Tuberculosis is caused by bacteria (Mycobacterium tuberculosis complex, which includes M. tuberculosis, M. bovis, and M. africanum) that are transmitted from an infectious source to susceptible persons primarily through the air (e.g., through coughing).

3 Most individuals who become infected do not experience clinical illness; infected individuals are usually asymptomatic and noninfectious. The only evidence of infection may be a reaction to a tuberculin skin test. Infection can persist for years, however, and infected persons remain at risk of contracting clinically apparent disease, especially if the immune system becomes impaired.

4 There are two kinds of tests that are used to determine if a person has been infected with TB bacteria: the tuberculin skin test 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.

5 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.

6 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.

7 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.

8 The Difference between Latent TB Infection
and TB Disease A Person with Latent TB Infection Has no symptoms Has Does not feel sick Cannot spread TB bacteria to others Usually has a skin test or blood test result indicating TB infection Has a normal chest x-ray and a negative sputum smear Needs treatment for latent TB infection to prevent active TB disease

9 A Person with TB Disease
• 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 - chills - fever - sweating at night • Usually feels sick • May spread TB bacteria to others • Usually has a skin test or blood test result indicating TB infection • May have an abnormal chest x-ray, or positive sputum smear or culture • Needs treatment to treat active TB disease 

10 Tuberculin skin test: The TB skin test (also called 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 health care worker will look for a raised, hard area or swelling, and if present, measure its size using a ruler.  Redness by itself is not considered part of the reaction.

11 The skin test result depends on the size of the raised, hard area or swelling. It also depends on the person’s risk of being infected with TB bacteria and the progression to TB disease if infected. Positive skin test: This means the person’s body was infected with TB bacteria.  Additional tests are needed to determine if the person has latent TB infection or TB disease.  A health care worker will then provide treatment as needed. Negative skin test:  This means the person’s body did not react to the test, and that latent TB infection or TB disease is not likely.

12 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.  An IGRA measures how strong a person’s immune system reacts to TB bacteria by testing the person’s blood in a laboratory. Two IGRAs are approved by the U.S. Food and Drug Administration (FDA) and are available in the United States: QuantiFERON®–TB Gold In-Tube test (QFT-GIT) T-SPOT®.TB test (T-Spot)

13 Positive IGRA: This means that the person has been infected with TB bacteria.  Additional tests are needed to determine if the person has latent TB infection or TB disease. A health care worker will then provide treatment as needed. Negative IGRA: This means that the person’s blood did not react to the test and that latent TB infection or TB disease is not likely.  IGRAs are the preferred method of TB infection testing for the following: People who have received bacille Calmette–Guérin (BCG). BCG is a vaccine for TB disease.  People who have a difficult time returning for a second appointment to look for a reaction to the TST. There is no problem with repeated IGRAs.

14 Who Should Get Tested for TB
TB tests are generally not needed for people with a low risk of infection with TB bacteria. Certain people should be tested for TB bacteria because they are more likely to get TB disease, including: People who have spent time with someone who has TB disease People with HIV infection or another medical problem that weakens the immune system People who have symptoms of TB disease (fever, night sweats, cough, and weight loss) People from a country where TB disease is common (most countries in Latin America, the Caribbean, Africa, Asia, Eastern Europe, and Russia) People who live or work somewhere in the United States where TB disease is more common (homeless shelters, prison or jails, or some nursing homes) People who use illegal drugs

15 Diagnosis of TB Disease
People suspected of having TB disease should be referred for a medical evaluation, which will include  Medical history, Physical examination, Test for TB infection (TB skin test or TB blood test), Chest radiograph (X-ray), and Appropriate laboratory tests

16

17 TB is NOT spread by shaking someone’s hand sharing food or drink touching bed linens or toilet seats sharing toothbrushes kissing

18 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

19 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.


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