in our program we refer to the cdc as the authority on tb information... see below:
what is latent tb infection?
persons with latent tb infection do not feel sick and do not have any symptoms. they are infected with m. tuberculosis
, but do not have tb disease. the only sign of tb infection is a positive reaction to the tuberculin skin test or tb blood test. persons with latent tb infection are not infectious and cannot spread tb infection to others
overall, without treatment, about 5 to 10% of infected persons will develop tb disease at some time in their lives. about half of those people who develop tb will do so within the first two years of infection. for persons whose immune systems are weak, especially those with hiv infection, the risk of developing tb disease is considerably higher than for persons with normal immune systems.
of special concern are persons infected by someone with extensively drug-resistant tb (xdr tb) who later develop tb disease; these persons will have xdr tb, not regular tb disease.
retrieved from: http://www.cdc.gov/tb/publications/f...ndactivetb.htm