What measurement of induration is considered positive for recent immigrants from high-prevalence TB countries?

For recent immigrants from high-prevalence tuberculosis (TB) countries, an induration measurement of greater than or equal to 10mm is regarded as positive. This threshold reflects the heightened risk and likelihood of latent TB infection in individuals from areas where the disease is more common. The standards for interpreting the tuberculin skin test results, specifically the induration size that categorizes a test as positive, vary based on risk factors and exposure history.

Individuals from high-prevalence countries may have a stronger immune response to the TB antigens used in the skin test, and thus a positive result at this lower threshold is significant. This ensures timely identification and treatment of those who may have been exposed to TB, thereby preventing the spread of the infection.