Can you test positive for TB and not spread it?
Persons with latent TB infection (LTBI) do not feel sick and do not have any symptoms, but usually have a positive reaction to the tuberculin skin test or TB blood test. They are infected with TB bacteria, but do not have TB disease. Persons with LTBI are not infectious and cannot spread TB infection to others.
TB disease in the lungs or throat can be infectious. This means that the bacteria can spread to other people. TB in other parts of the body, such as the kidney or spine, is usually not infectious. People with TB disease are most likely to spread it to people they spend time with every day.
After taking TB medicine for several weeks, a doctor will be able to tell TB patients when they are no longer able to spread TB germs to others. Most people with TB disease will need to take TB medicine for at least 6 months to be cured.
Does a positive test mean that I can give TB to someone else? Not necessarily. After you have a positive PPD skin test, you must have a chest x-ray and a physical exam to make sure that you don't have active disease and that you are not contagious. If usually takes only a few days to tell whether you're contagious.
In realistic settings of low risk of TB infection, even with high cutoffs and confirmation, the post-test probability of a positive QFT test on serial testing may still only approach 60%, while annual testing with a single QFT using the recommended diagnostic cutoff may cause over 25% of individuals to have a false- ...
The causes of these false-positive reactions may include, but are not limited to, the following: Previous TB vaccination with the bacille Calmette-Guérin (BCG) vaccine. Infection with nontuberculosis mycobacteria (mycobacteria other than M. tuberculosis)
Persons who have or are suspected of having infectious TB disease should be placed in an area away from other patients, preferably in an airborne infection isolation (AII) room.
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 disease.
What if I have a positive test for TB infection? If you have a positive reaction to the TB blood test or TB skin test, your doctor or nurse will do other tests to see if you have TB disease. These tests usually include a chest x-ray. They may also include a test of the sputum you cough up.
Patients with active TB may be isolated until they are no longer contagious – often a period of two weeks or more after the initiation of antibiotic therapy.
Can TB be wrongly diagnosed?
TB can be wrongly diagnosed
Antibodies may also develop against other organisms which again could wrongly indicate they have active TB. In addition, different organisms share the same antigens, making tests results unreliable. These factors can result in TB disease not being identified or wrongly diagnosed.
* For employees who are otherwise at low risk for TB and who are tested as part of an infection control screening program at the start of employment, a reaction of 15 mm is considered positive.
Once you have a positive TB skin test you will always have a positive TB skin test, even if you complete treatment. Ask your doctor for a written record of your positive skin test result. This will be helpful if you are asked to have another TB skin test in the future.
Your health care provider MUST check your arm 2 or 3 days after the TB skin test, even if your arm looks OK to you. If you have a reaction to the test, it will look like a raised bump. Your health care provider will measure the size of the reaction. If there is a bump, it will go away in a few weeks.
Are test results accurate? The TB skin test is a widely used test. There are known circ*mstances that can lead to false negative and false positive test results. There are several factors that can contribute to false positive test results, in which a person has a positive test result despite not having an infection.
People with latent TB infection: Have no symptoms. Don't feel sick. Can't spread TB bacteria to others.
People with symptomatic TB are contagious until they have taken their TB medications for at least two weeks. After that point, treatment must continue for months, but the infection is no longer contagious.
...
Identifying infection.
| Size of induration | Result |
|---|---|
| 15 mm or more | positive |
This means you probably have TB germs in your body. Most people with a positive TB skin test have latent TB infection. To be sure, your doctor will examine you and give you a chest x-ray. You may need other tests to see if you have active TB disease.
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. 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.
Will latent TB show up on xray?
Chest Radiograph
Lesions may appear anywhere in the lungs and may differ in size, shape, density, and cavitation. These abnormalities may suggest TB, but cannot be used to definitively diagnose TB.
A positive skin or blood test means you have been infected with the germs—Latent (inactive) Infection. If you have a positive test, you will need a chest x-ray to find out if the germs have caused any damage in your lungs—Active Disease. You may be asked to cough up sputum (mucus) from your lungs to check for TB germs.
Results. Redness alone at the skin test site usually means you haven't been infected with TB bacteria. A firm red bump may mean you have been infected with TB bacteria at some time. The size of the firm bump (not the red area) is measured 2 to 3 days after the test to find out the result.
