Expert: Violet Argo RN - 8/18/2008

Question
Hello

I am healthy 31 years old man with very active life style, but few months ago I was surprised when I found that I have a positive TB skin test with 15mm swilling on my skin. After meeting with 3 different doctors specialized in lung, internal medicine, infections, and after several readings related to this topic, I found the following:  

• All the three doctors recommended that I start taking INH for 9 months.

• There is a 10 percent chance that the latent TB germ will wake up in my body if I don’t take INH medication.

• Some people had positive TB test, but now they are very old and the germs never woke up in their whole life, and they never took INH or isoniazid.

• My BCG vaccine will not decrease the probability of getting the disease.

• INH can reduce the risk of getting the disease by 90 %.

• Quantiferon blood test or Mucus test can help to know about the infection, but doctors refused to do them for me.

• The skin test is of limited value in diagnosis of active TB because of its relatively low sensitivity and specificity. False positive reactions may be caused by infections with non TB mycobacterium.

• At present, the American Thoracic Society recommends restricting the use of isoniazid prophylaxis to tuberculin reactors (people with positive skin tests) younger than 35 and to those older than 35 who are at increased risk for activation of the infection. Factors that increase the risk of activation include diabetes, renal failure, alcoholism, immunosuppressant and abnormal chest x-rays suggesting previously active tuberculosis.

My question is:

1- Why my BCG vaccine that I took when I was a child, was not able to control infection, or is not able to control TB disease?

2- INH might cause hepatitis or effect the liver, or other body organs. With 10 percent chance I may never get TB disease? Should I take INH or no?

Thank you for your helpful answers


Answer
This is a very complex question. I am not an expert in these areas, but I will do my best with some of this.

Did you have a chest X-ray to confirm TB?

I was always told people that had taken BCG should never take a skin TB test because they would react +.

I personally react + to the test because I am allergic to the serum used, so I have to have a yearly chest X-ray for work.

I cannot answer wether you should take the INH or not. I belive you  should consider the recommendations of the ATS, and discuss it with your doctor.


Good luck on a difficult decision.