Question

After doing a chest x-ray, your doctor says the results are inconclusive. So, you are put on a six-month course of isoniazid to be safe. About six months later, while sitting in your medical microbiology class during a lecture on tuberculosis, you suddenly realize why you had that positive reaction to the skin test six months earlier. It had nothing to do with being infected, but was because you were born in Norway and your family moved to the United States when you were four years old.

3. What is going on here? Discuss in detail. 4. A while later, you told a friend of yours who is HIV-positive about your TB scare. She said that her doctor doesn't typically use the TB skin test on her, even though people with HIV are more susceptible to TB. Why is the skin test not always a reliable TB test for those with HIV?

Answer 1

3) The following are the possibilities where the Mantoux test(Test for TB) is reactive-

1. Active TB infection
2. Latent TB Infection
3. If BCG Vacination is done

So the person may gone to doctor due to any respiratory problems suggestive of TB. To find the diagnosis the Doctor may have done MANTOUX TEST which further came as REACTIVE.To confirm TB the doctor further ordered CHEST X-RAY which was inconclusive of TB so its not TB .Due to his concern over Community he has given prophylactic treatment to the person i.e ISONIAZID for 6 months.

why TB test reactive in the person?

As the person stayed in NORWAY where TB has more prevalance the person may be vaccinated with BCG vaccine (OR) the Person is Post TB patient(who has TB antibodies)

4)Tuberculin Skin test is not reliable in people having HIV because-

As in HIV patients the immunity system decrease as the disease progresses which leads the person inability to produce antibodies.This leads the person more prone to systemic infections which also includes TB.

so when the skin test is performed the test becomes NON REACTIVE as the body cannot produce antibodies against the skin test that doesnt form any inflammation even though he has active infection.

So the lack of immunity power in HIV that leads to NON-RELIABLE on skin test.

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