The test is “positive ” if there is a bump of a certain size where the fluid was injected. 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.
If your skin test or blood test is positive, you will likely be sent for a chest X-ray, which looks for certain small spots in your lungs. These spots are a sign of TB infection and indicate that your body is trying to isolate the TB bacteria. If your chest X-ray is negative, you likely have latent TB.
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.
A positive TB test result means only that TB bacteria has been detected. It does not indicate whether the person has active TB or a latent infection. This requires additional testing. TB disease can be diagnosed by medical history, physical examination, chest X-ray, and other lab tests.
Many people who have latent TB infection never develop TB disease. In these people, the TB bacteria remain inactive for a lifetime without causing disease. But in other people, especially people who have weak immune systems, the bacteria become active, multiply, and cause TB disease.
You need to stay home from work or school so that you don’t spread TB bacteria to other people. After taking your medicine for a few weeks, you will feel better and you may no longer be infectious to others. Your doctor or nurse will tell you when you can return to work or school or visit with friends.
If you have a positive PPD skin test (first or second step), you will be referred to a physician to rule out the possibility of active tuberculosis before you can begin to work in a healthcare facility.
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 result depends on the size of the raised, hard area or swelling.
Yes, this is true. Even after you finish taking all of your TB medicine, your TB skin test or TB blood test will still be positive.
Also—don’t scratch the spot. If the area itches, put an ice cube or cold cloth on it. It is okay for the test spot to get wet, but do not wipe or scrub the area. Return to the clinic or doctor’s office in 2 to 3 days so your healthcare provider can look at the test spot on your arm.
A: You can take showers and baths as you normally do. Q: What do I do if my arm itches or blisters? A: Put an ice cube in a washcloth and place it on your arm. DO NOT SCRATCH!
Side effects are uncommon from the Mantoux skin test. However, a person who has been exposed to TB germs may occasionally have a sizable reaction, which may cause some mild itching, swelling or irritation. These kinds of reactions should disappear in one to two weeks.
By the dawn of the 19th century, tuberculosis —or consumption—had killed one in seven of all people that had ever lived. Throughout much of the 1800s, consumptive patients sought “the cure” in sanatoriums, where it was believed that rest and a healthful climate could change the course of the disease.
Kissing, hugging, or shaking hands with a person who has TB doesn’t spread the disease. Likewise, sharing bed linens, clothes, or a toilet seat isn’t how the disease spreads either.
Current models of untreated tuberculosis that assume a total duration of 2 years until self-cure or death underestimate the duration of disease by about one year, but their case fatality estimates of 70% for smear-positive and 20% for culture-positive smear-negative tuberculosis appear to be satisfactory.