Tb test led to bcg vaccine because of no immunity.?

What does it mean if you have a tb test and the doctor recommends you get a bcg vaccine to prevent tb? This happened to one member of a family. Others were given the same test and told they had immunity and therefore did not need bcg. Does this mean the non vaccinated had tb at one time unknowingly?

In the Mantoux test 0.1 ml of 1 in 10,000 purified protein derivative (tuberculin) is injected intradermally and the result is read two to three days later. A positive result is indicated by redness and induration of at least 10 mm in diameter. This implies previous exposure to tuberculin protein - thus it could represent previous BCG exposure. It is a type IV hypersensitivity reaction. Alternative tuberculin tests are available for large-scale screening (Heaf and Tine tests) but they are not as accurate as the Mantoux test. The Heaf test is a skin test performed in order to determine whether or not a child is immune to tuberculosis. Small skin punctures are produced on the forearm, through which tuberculin is introduced. If the test is positive a reaction causes the skin to become red and raised, indicating that there is an immunity already. If the test is negative a BCG vaccine is then offered. It is not usual to have any major side effect to BCG vaccine, other than the small sore or blister at the injection site. BCG vaccination, (also called a jab, injection or immunisation) has been shown to give 70%-80% protection against TB (Tuberculosis). The vaccine is given in a single dose following a 鈥榥egative鈥?heaf test. The vaccine contains a weak form of the disease. Local policy differs regarding the vaccination of babies. Some babies considered 鈥渁t risk鈥?will be given the vaccine at birth. This includes those born into families with members from high-risk countries, those babies who will be travelling to high-risk countries and those babies living in households were persons of a high risk are also living. Advice should be taken from a health professional.
Hope this helps
Matador 89

the bcg is given to those who HAVE inactive tuberculosis, to prevent it becoming active.

It means one has been exposed to T.B. and may be at a greater risk . It does not mean that one has or had it.

BCG,or bacilli Calmette-Gu茅rin, is a vaccine for
tuberculosis (TB) disease. BCG is used in many
countries with a high prevalence of TB to prevent
childhood tuberculous meningitis and miliary disease.
However, BCG is not generally recommended for use
in the United States because of the low risk of infection
with Mycobacterium tuberculosis, the variable
effectiveness of the vaccine against adult pulmonary TB,
and the vaccine鈥檚 potential interference with tuberculin
skin test reactivity. The BCG vaccine should be
considered only for very select persons who meet
specific criteria and in consultation with a TB expert.
No they don't require vaccination unless they are in constant exposure to TB patients e.g Health Workers etc.

If your in the us you don't need a BCG vaccine. Now if you outside the us BCG is a comon vaccine given to children. The BCG vaccine dosn't always (95%) elicit an immune responce. The tb test is designed to "react" with antibodies to tb. So if you have no reaction and live in a country where BCG vaccination is required or recommended then you need a BCG booster. This means that the non reactant has never seen tb and didn't respond to BCG vaccine

Tuberculosis--The Return of a Killer :
- A Death Toll That Rivals War
- Triumph and Tragedy
- A Global Solution--Is It Possible?
- TB Fact Sheet - TB and Fashion
- Is It Easy to Catch TB?
http://www.watchtower.org/e/19971222/art...

I once looked TB up in a book published my the AMA. One thing it said was that

the skin test for TB is inconclusive in 10% of those tested.

In other words, of those tested who actually were carriers of TB, 10% did NOT have skin reactions ...

Skin tests are what are given to people who work in hospitals.