BCG vaccine and Mantoux test

[Belle Epoque]

There's a recent TB thread which is prompting me to ask the following question (but figured I'd create a separate thread to keep things neater.)

What are your thoughts regarding the BCG vaccine in childhood causing false-positive results with the 2 step Mantoux test in adulthood?

I've heard various explanations and not sure which camp to believe.

[cleback]

I was born in East Africa where I was vaccinated with the BCG vaccine at the age of 11 years. I had a positive mantoux test (2 step) at the age of 50 years. My Chest X ray was clear but the Docs were convinced I had latent TB. They persuaded me to take isoniazid but my monthly blood tests were not monitored and after 5 months I went to my family doctor feeling quite unwell. My liver enzymes were very high and I had hepatitis. Needless to say I was very angry and still sceptical about the diagnosis of Latent TB. I finally managed to get the quantiferon blood test which conclusively proved that I did not have latent TB and my skin reaction was therefore due to the BCG vaccination 40 years before. You would think that this happened in the third world country but the care I received was in Canada and by what I thought were knowledgable Infectious Disease Doctors. The doctor in charge of my care was even a professor at the university here. It's quite surprising.

That's crazy... can't believe that happened. Hope you're feeling well now.

[GIEndoRN, BSN, RN]

This is interesting to hear, I've also had the BCG vaccine. When I was younger, I had a few false positives but not in many years. I still get a violent skin reaction to Mantoux though. I want to gnaw my arm off the first night because it itches so bad. Thankfully it only lasts a day or two.