In 18 studies involving 1,169,105 subjects, the absolute prevalence of false-positive TST from NTM cross-reactivity ranged from 0.1% to 2.3% in different regions. Conclusions: The effect on TST of BCG received in infancy is minimal, especially > or =10 years after vaccination.
Additionally, can you test positive for TB and not have it?
Persons with latent TB infection (LTBI) do not feel sick and do not have any symptoms, but usually have a positive reaction to the tuberculin skin test or TB blood test. They are infected with TB bacteria, but do not have TB disease.
One may also ask, what can cause a false-positive TB Gold test? (1) False-positive results may occur in patients with prior infection with M marinum, M szulgai, or M kansasii. Negative: No IFN-gamma response to M tuberculosis antigens was detected. Infection with M tuberculosis is unlikely.